# Ph profile



## Chrispowell (29 Aug 2022)

Morning all, 

Does anyone have a good example of a pH profile from their tank? 

I'm going to measure mine and assume we look for a good 1ph drop before lights on followed by a stable pH throughout the lighting period?

Is there any detrimental effects on plants if the drop is greater then 1 or continues to drop throughout the lighting period?

Thanks 

Chris


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## Yugang (29 Aug 2022)

The following thread is a good starting point
Dialling in the CO2 injection Rate and CO2 Profiles



Chrispowell said:


> Is there any detrimental effects on plants if the drop is greater then 1


Many hobbyists target 1, this should be around 30 ppm CO2. Higher would not harm the plants, but you may put your lifestock at risk. CO2 stability during photoperiod is more important than the absolute value, so for the safety of your lifestock you may, at least initially, not want to exceed the 1.0 pH drop.



Chrispowell said:


> detrimental effects on plants if .... continues to drop throughout the lighting period?


Yes there is. You want the pH to be within 0.1 variation in the entire photoperiod (where the first 3-4 hours are believed to be most important)



Chrispowell said:


> Does anyone have a good example of a pH profile from their tank?


Every tank will be different. The key is to focus on stability during photoperiod, what happens before and after photoperiod is less relevant.


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## _Maq_ (29 Aug 2022)

Yugang said:


> around 30 ppm CO2. Higher would not harm the plants


I've read some scientific papers which stated that more than 40 mg/L CO2 is more harmful than beneficial to plants.
The growth response to CO2 enrichment follows Michaelis-Menten kinetics with half-saturation values in the range from 4 to 9 mg/L. According to this, more than 20 mg/L should exert only limited effect, the more so that our lighting is inevitably weaker than natural light.
Many aquarists would swear that 30 mg/L works better than 20 mg/L, I know. I wonder whether they truly "know" or just "believe", and why their observation differs from what scientists say. Water flow surely has its effect, limiting photorespiration. Otherwise, I've got no answer.


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## Yugang (29 Aug 2022)

_Maq_ said:


> I've read some scientific papers which stated that more than 40 mg/L CO2 is more harmful than beneficial to plants.


I'm trying to help OP with a practical and not complicated summary, but let me comment...

 as we discussed in several other threads, most of us are not able to accurately measure CO2 ppm and may easily be 50% off. So how credible are any statement about mg/L?
many experienced hobbyists, with great planted tanks, claim (for what it is worth) to be at 50 ppm and more. 



_Maq_ said:


> I wonder whether they truly "know" or just "believe", and why their observation differs from what scientists say.


Most of us can not accurately measure CO2 ppm, so indeed we 'believe'. 

My suggestion would be to park this in depth discussion, and focus in this thread on OP's questions.


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## erwin123 (29 Aug 2022)

Chrispowell said:


> Morning all,
> 
> Does anyone have a good example of a pH profile from their tank?
> 
> ...








To answer your question, here's my old profile. I'm sort of too lazy to do a complete profile every 15 minutes now.... maybe when I have more free time as my pH variance now is probably not as good (0.1-0.15)
My drop checker is lime green only throughout the photoperiod, it never turns yellow.


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## Yugang (29 Aug 2022)

erwin123 said:


> To answer your question, here's my old profile. I'm sort of too lazy to do a complete profile every 15 minutes now.... maybe when I have more free time as my pH variance now is probably not as good (0.1-0.15)
> My drop checker is lime green only throughout the photoperiod, it never turns yellow.


Having pH stable from day to day, and week to week (these are the typical timelines for the plants to adapt themselves with their Rubisco) is the more challenging part. 
Most likely day to day stability is at least as important as the profile during a one-day photoperiod, and often overlooked when optimizing CO2.


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## _Maq_ (29 Aug 2022)

Yugang said:


> Having pH stable from day to day, and week to week (these are the typical timelines for the plants to adapt themselves with their Rubisco)


This is not the first time I've noticed here that plants need a while (counting in days?) *to adapt their Rubisco*. This is quite new to me. In nature, terrestrial plants face no CO2 fluctuations, but light varies significantly from day to day, from hour to hour, due to the weather. While submerged plants must be adapted to both varying light intensity and significant CO2 variability every day. I daresay there's no stability in natural waters in respect of lighting as well as CO2 availability. However, the lines are rather smoother when we permit for bicarbonate use.
Can anyone point to any scientific explanation?


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## Yugang (29 Aug 2022)

_Maq_ said:


> This is not the first time I've noticed here that plants need a while (counting in days?) *to adapt their Rubisco*. This is quite new to me. In nature, terrestrial plants face no CO2 fluctuations, but light varies significantly from day to day, from hour to hour, due to the weather. While submerged plants must be adapted to both varying light intensity and significant CO2 variability every day. I daresay there's no stability in natural waters in respect of lighting as well as CO2 availability. However, the lines are rather smoother when we permit for bicarbonate use.
> Can anyone point to any scientific explanation?


No one understands Rubisco as good as @ceg4048 😊
He’s also written about it in many posts, you may want to do a search on the forum.


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## Zeus. (29 Aug 2022)

_Maq_ said:


> Water flow surely has its effect


IMO water flow is more important than [CO2], as the better the flow around the plants the better the localised supply of CO2


Yugang said:


> No one understands Rubisco as good as @ceg4048 😊
> He’s also written about it in many posts, you may want to do a search on the forum.


Use 'rice' as your search, as most of the research @ceg4048 mentions is from studies of rice


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## Yugang (29 Aug 2022)

Yugang said:


> No one understands Rubisco as good as @ceg4048 😊
> He’s also written about it in many posts, you may want to do a search on the forum.



@_Maq_ This is        one of ceg4048 best posts on this topic IMO 

For the context of OP's question, the most relevant take away from pH profiling is that you want pH to be stable *within photoperiod and within the timeframes that the plants needs to adjust itself to changes.* Otherwise, using @ceg4048 terminology, the plant is in a permanent state of confusion and expensive adaptation.

Personal note:
I do not want to put words in @ceg4048 mouth, but let me explain one reason why I found his post so valuable. It is for me not about the science of Rubisco, yet about really understanding how and why stability is so important. Let me guess, perhaps 10% of high tech hobbyists have ever done a pH profile? But then, I have never seen a post where day to day and week to week stability was measured and optimised. Have I missed something?
Now, from @ceg4048 post, Rubisco needs typically weeks to adjust. Over the past weeks and months I have been daily checking my pH profile, and discovered actually how easy it is for pH to go left or right on day-to-day and week-to-week basis. It is really the details in the tank (mostly injection, flow and surface agitation) that matter to get pH stable within 0.1 over a let's say 2 weeks period. This is one observation where @ceg4048 post opened my eyes.

Attachment: A PhD thesis that studies variations in availability of resources that aquatic plants need for photosynthesis. Special bonus for @_Maq_ 👨‍🎓
​​


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## Chrispowell (1 Sep 2022)

Thanks for all the input everyone! It's always nice to see a thread develope! 

I started to document my ph levels today, will take a few days but when u have results I will post them up 

Thanks 

Chris


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## Wookii (1 Sep 2022)

Chrispowell said:


> continues to drop throughout the lighting period



This usually suggests you have insufficient surface agitation. Though it might seem counter productive, increasing the surface agitation will off-gas more CO2, which will mean you need to increase the injection rate to hit your target 1.0pH drop. However the net result will be a quicker pH drop, and more stable CO2 levels through the photo period.


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## GreggZ (1 Sep 2022)

Chrispowell said:


> Is there any detrimental effects on plants if the drop is greater then 1 or continues to drop throughout the lighting period?


Notwithstanding some of the comments above, I have never found a pH drop of greater than 1.0 detrimental to plants. In fact, for most high tech high light tanks somewhere around a 1.4 pH seems to be about optimum. I have tested this in my own tank many times over many years.

But keep in mind that is relation to my very high light tank full of stems. In a tank that is not driven very hard and is full of slower growers there is a law of diminishing returns. Light is the gas pedal. Turn it up and plants need more CO2. Turn it down and they need less. 

In a high energy tank keeping CO2 optimized and steady pays dividends. There are loads of ways to get it wrong. Many bang their heads against the wall chasing fertilization theories, when turning up the CO2 is the quickest remedy. 

As to a pH profile I have found getting to very near pH peak drop when lights turn on is best. And then the tricky part is keeping that level steady during the lighting period. All of this is based on my personal experience and observations over a long period of time. I have found most scientific studies offer little help to the aquarist, as no one is performing true scientific experiments based on our glass boxes packed with a wide variety plants. 

Most aquarist would do better to use trial and error and observation to fine tune their unique ecosystem. But to do so takes time and patience, which not many are willing to do.


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## Yugang (2 Sep 2022)

GreggZ said:


> I have found most scientific studies offer little help to the aquarist, as no one is performing true scientific experiments based on our glass boxes packed with a wide variety plants.


Inspired by @ceg4048 posts (which I think are closest to what is a theoretical base, posted on this forum) I took some time to further research literature and other fora. I have not found any scientific article that gives a full answer, but perhaps I still share what I found and how I interpret it.

Some of the leading scientists, from what I found and interpret, are Tom V Madsen, Stephen Maberly and George Bowes. Now George Bowes happens to be one of Tom Barr's professors, Tom speaks highly of him, and I suspect that Tom driving the importance of Rubisco and CO2 stability is at least influenced by the scientific community around G Bowes.

A quote from the attached article, authored by Madsen, Maberly and Bowes:
_The data presented here illustrate the very plastic morphological and physiological response to inorganic carbon by submersed, freshwater angiosperms. A similar plasticity is exhibited by some cyanobacteria and microalgae (Badger and Price, 1994). These responses by aquatic photolithotrophs to CO2 and HCO; have ecological relevance because of the high spatial and temporal variation in availability of the forms of DIC in natural freshwaters (Tailing, 1976; Van et al., 1976; Maberly, 1996)._​
A search on articles from either of these three authors will give the bulk of relevant documents for fresh water plants adaptation to dissolved inorganic carbon and photosynthesis.

What I learned, and is of course obvious to the more educated members here , is that aquatic plants have developed a wide variety of adaptations to a changing environment (water depth, turbidity, light reaching the leaves, pH, CO2 and HCO3 sources, emersed/submerged, flow, etc) and how they balance the three main photosynthesis pathways C3, CAM and C4. There is a variety of mechanisms at play, and at at best any scientific article compares 2 or 3 plant species. It seems  impossible to make scientific statements that are true for all aquatic plants, or even to all plants in our tank. Every plant is different when it comes to adaptation to dissolved inorganic CO2, and Rubisco is only a part of the story.

Now any adaptation to a changing environment means that the plant has to invest in its machinery, and that comes at a cost. It seems that the CO2 stability in our tanks is to minimize these adaptation costs, for any plants - whatever the mechanism is for that particular species. True, lakes and rivers have  variations of dissolved inorganic carbon, but we choose pragmatically to make our tanks a good home for each species and at a minimal avoidable cost of continuous adaptation. This is how I interpret all that I read, as it applies to our hobby.

I attach just one article, for those interested let me know and can forward more recent publications as well. Concur with  @GreggZ , more science does not necessarily help for our hobby.


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## Chrispowell (6 Sep 2022)

Hi all, started to do a ph profile..

Can anyone explain what's going on in my video? Tank pH measures one thing - take the water out of the tank and the reading is miles different?!









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Thanks 

Chris


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## RLee2 (6 Sep 2022)

Chrispowell said:


> Hi all, started to do a ph profile..
> 
> Can anyone explain what's going on in my video? Tank pH measures one thing - take the water out of the tank and the reading is miles different?!
> 
> ...


You set the test cup of water directly on the light. I wonder if electrical interference from your LED light is causing the erroneous reading?


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## Chrispowell (6 Sep 2022)

It's a thought... let me try it somewhere else...


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## Chrispowell (6 Sep 2022)

Yes you are correct! Thankyou! 

Now... I'm struggling to get anywhere near a 1.0ph drop! 

Water just before co2 on is 6.78ph.

Water just before co2 off is 6.46 (drop checkers are yellow at this point).

Co2 currently on 5 hours before lights! I went back to the in tank diffuser and I can visibly see alot of gas coming from the diffuser.  

What further information would assist?

Thanks 

Chris


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## Wookii (6 Sep 2022)

Chrispowell said:


> Yes you are correct! Thankyou!
> 
> Now... I'm struggling to get anywhere near a 1.0ph drop!
> 
> ...



Remember your 1.0pH drop is supposed to be from a degassed sample of tank water (put some in the jog and leave for 24 hours stirring occasionally), not from the CO2 switch on point in-tank.

It’s highly unlikely your tank gets fully degassed and returns to equilibrium CO2 levels with the atmosphere overnight. I’d wager your 6.49pH reading is, or maybe more than, a 1.0pH drop.


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## RLee2 (6 Sep 2022)

Chrispowell said:


> Yes you are correct! Thankyou!
> 
> Now... I'm struggling to get anywhere near a 1.0ph drop!
> 
> ...


Some pics of your set up would help tremendously.  Provide the specs' of your setup, tank size, filter/pump flow rate, as much detail as you can. 
Right off it would seem there is a discrepancy between the drop checker and the ph pen results. Did you properly calibrate the ph pen?


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## RLee2 (6 Sep 2022)

Wookii said:


> Remember your 1.0pH drop is supposed to be from a degassed sample of tank water (put some in the jog and leave for 24 hours stirring occasionally), not from the CO2 switch on point in-tank.
> 
> It’s highly unlikely your tank gets fully degassed and returns to equilibrium CO2 levels with the atmosphere overnight. I’d wager your 6.49pH reading is, or maybe more than, a 1.0pH drop.


Yes I agree except for one point. His measured difference between high and low ph is .32. I know a tank will not off gas completely over night, unless maybe one is running heavy aeration. From my experience one recovers about 2/3 - 3/4 of the ph over night. Based on a 1.0ph drop that would be a difference between high and low ph of .66-.75 ph. I guess if one has zero water surface movement, no surface skimmers, low water circulation, the losses could be lower?


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## Wookii (6 Sep 2022)

RLee2 said:


> Yes I agree except for one point. His measured difference between high and low ph is .32. I know a tank will not off gas completely over night, unless maybe one is running heavy aeration. From my experience one recovers about 2/3 - 3/4 of the ph over night. Based on a 1.0ph drop that would be a difference between high and low ph of .66-.75 ph. I guess if one has zero water surface movement, no surface skimmers, low water circulation, the losses could be lower?



Yes, I would expect it to be a little higher at CO2 on the next day, though I’d imagine a 0.5pH increase overnight is fairly common. However if his drop checker is yellow at the end of the photo period, it would suggest a) far greater than 30ppm CO2 associated with 1.0pH drop is being achieved, and b) there is a low level of surface agitation causing a continuous rise in pH levels throughout the photo period.


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## RLee2 (6 Sep 2022)

Wookii said:


> Yes, I would expect it to be a little higher at CO2 on the next day, though I’d imagine a 0.5pH increase overnight is fairly common. However if his drop checker is yellow at the end of the photo period, it would suggest a) far greater than 30ppm CO2 associated with 1.0pH drop is being achieved, and b) there is a low level of surface agitation causing a continuous rise in pH levels throughout the photo period.





RLee2 said:


> Some pics of your set up would help tremendously.  Provide the specs' of your setup, tank size, filter/pump flow rate, as much detail as you can.
> Right off it would seem there is a discrepancy between the drop checker and the ph pen results. Did you properly calibrate the ph pen?


Agreed..... this is why I think the ph pen might need to be calibrated. What's even more confusing is if you watch Chrispowell's video when he sticks the ph pen in his tank it reads 6.02!


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## Chrispowell (6 Sep 2022)

Tank specs..

ADA 90H 
90 x 45 x 60

Twinstar 900S turned down 50%

Ro water 

Two filters, oase biomaster 600 using stainless steel outlet and surface skimmer inlet.

Jbl crystalprofi 1501 with glass lily pipes.

Eheim surface skimmer 

Co2 on at 09:00, lights on at 14:00
Co2 off at 20:00 lights off at 21:00


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## Chrispowell (6 Sep 2022)




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## Chrispowell (6 Sep 2022)




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## Chrispowell (6 Sep 2022)

Links to videos -


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## Wookii (7 Sep 2022)

Interesting @Chrispowell - it certainly looks to me like you're dosing a fair amount of CO2, however I'm also surprised how little movement there is in the tank with two filters on it - the CO2 bubbles don't looks to be travelling very far. The mosses and stems from the middle of the tank and to the right don't seem to be moving at all. Do you have any kinks in the filter hoses? What media do you have in the filters?

I'd also want more surface agitation that you're achieving now, I would raise both filter outlets. I would generally run a lily pipe with the 'bulb' part just below the surface. I'd also consider switching the other stainless steel filter outlet to the rear left corner of the tank to get more circular flow, and put the filter inlets in the either the remaining two corners to promote that flow pattern further, or in both the rear corners to help draw CO2 enriched water through the stems.

The stems themselves aren't looking overly healthy, and though it's hard to tell from the video, it looks like you could have some chlorosis and stunting going on. You say you are using RO water - what is your remineralisation and fertilisation regime?


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## Chrispowell (7 Sep 2022)

Thankyou for the continued support, I aim to give the tank a good clean down today and move the filter inlet and outlet as suggested. I was always looking  to avoid flow at the back of the tank as I was concerned it would affect the growth pattern of the stems?

Current ferts are below, I'm mixing my own ei style with no added remineralisation


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## Wookii (7 Sep 2022)

Chrispowell said:


> no added remineralisation



You need to add some remineralisation, as you are notably missing calcium from your dosing. You don't need a lot of it, if you don't intend to have any shrimp or snails, but the plants do need some.


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## Chrispowell (7 Sep 2022)

Wookii said:


> You need to add some remineralisation, as you are notably missing calcium from your dosing. You don't need a lot of it, if you don't intend to have any shrimp or snails, but the plants do need some.




I will start to add a scoop of shrimp king kh+ gh once a week with water change... could this be the issue with the plant growth?


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## Wookii (7 Sep 2022)

Chrispowell said:


> I will start to add a scoop of shrimp king kh+ gh once a week with water change... could this be the issue with the plant growth?



I wouldn't bother with the Shrimp King if it adds to the KH, that's unnecessary. Just grab some Calcium Chloride (CaCl2) - you already have the Magnesium Sulphate (MgSO4). I use RO, and I don't include the MgSO4 in my macro mix, but instead just dose it separately after a water change to remineralise based on the water change quantity and the dGH I want to target.

So assuming you change 120 litres of water a week on your tank, you remineralise your 120 litres to a chosen dGH target.  The ratio of calcium to magnesium is something for debate, but many people use a 3:1 ratio, and I do the same. A side bonus of that if you're dry dosing is that if you simply use the same physical weight of CaCl2 and MgSO4, it comes out pretty close to that 3:1 ratio, so easier to remember and minimises effort.

So, say you target 3dGH, you'd add about 6 grams (about one teaspoon measure) of each to your 120 litres (or directly to the tank after changing the 120 litres). For a target of 6dGH, which is closer to your 10ppm EI target for Mg, just double that (so 2 x teaspoons of each after the water change).


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## Wookii (7 Sep 2022)

Chrispowell said:


> could this be the issue with the plant growth?



It could be, as a calcium deficiency does apparently cause stunting of leaves. It's just not very frequently encountered as there is never a shortage of it for tap water users, and most RO users add it in abundance even if they target a low dGH.


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## Chrispowell (7 Sep 2022)

CaCl2 purchased, thankyou for the pointers!


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## Chrispowell (10 Sep 2022)

So as luck would have it my co2 ran out two days ago and I have had to wait until today before re-stocking.

This had given me a chance to get a reading for the de-gassed water...


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## Chrispowell (10 Sep 2022)

So as suggested I have made a couple of changes..

Large waterchange and then dosed calcium.

Raised the lily pipe to create more surface movement, moved the stainless inlet and outlet to the opposite corner to the lily pipes to increase flow.

Now I will aim to get a 1.0ph drop for lights on and then keep them rate stable for the lighting period. 

Video below


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## Chrispowell (10 Sep 2022)




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## Chrispowell (12 Sep 2022)

Wookii said:


> You need to add some remineralisation, as you are notably missing calcium from your dosing. You don't need a lot of it, if you don't intend to have any shrimp or snails, but the plants do need some.



Calcium arrived today, I added a tea spoon to the tank- is it possible to add to my ei mix?

Thanks

Chris


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## Wookii (12 Sep 2022)

Chrispowell said:


> Calcium arrived today, I added a tea spoon to the tank- is it possible to add to my ei mix?
> 
> Thanks
> 
> Chris



No, it'll react with other elements in the mix, and precipitate out. Keep it separate. You can make up a solution with it though, which is sometimes easier to dose, and mixes more easily.


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## Chrispowell (14 Sep 2022)

Thanks Wookii, did a 50% water change last night and once the filters were restarted I mixed 6g of calcium in a measuring jug of water.. swirled it around until dissolved and added to the tank.

You mentioned adding more for shrimp... how much would be right? Would I also need to increase magnesium to compensate?

Thanks 

Chris


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## Wookii (14 Sep 2022)

Chrispowell said:


> You mentioned adding more for shrimp... how much would be right? Would I also need to increase magnesium to compensate?



It depends on the shrimp you want to keep. About 5-6 dGH is a good starting point for most shrimp, Neocaridina (such at cherry shrimp) do better with a bit more, Caridina can have a little less, but in my experience Caridina seem to struggle in a CO2 injected tank, perhaps the one exception being Amano's.

Tangerine Tigers (a wild type Caridina) are an option if you want to keep the water TDS low - mine seem to be breeding well in 3-4 dGH, but again, I'm not sure how they would get on with CO2 injection.

Either way you'd need to start getting the CO2 levels down before adding any livestock, as level that cause a yellow drop checker will be too high for most critters.


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## Chrispowell (17 Sep 2022)

Morning all,

I believe co2 is now on track.

100% degassed aquarium water is ph 7.68.

Now at lights on we are at 6.66 and this drops tp 6.65 by the end of the lighting period.

Plant growth is yet to improve but I guess these things take time, will post so updated images in a week to see if everything is heading in the right direction.

Many thanks

Chris


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## chvvkumar (28 Sep 2022)

I finally have something I can contribute. I am using an Apex to control my CO2 via. pH monitoring. Here is my pH profile. I like to keep my pH between 6.7 and 6.75 during the photo period.

I noticed my pH was not rising back up as much as I expected during the night. I even have an Eheim Skimmer running the whole time. So I first added an air stone for one night, temporaryly, to see if it made any difference and boy it did. Then I bought a more permanent one and added that yesterday.







Looking farther back,


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## Chrispowell (28 Sep 2022)

Thanks for this! 

Currently running with no fish so believe they're are no detrimental effect on the plants. Similar experience in my tank with the pH remaining quite low throughout the night compared with totally de-gassed aquarium water.

Chris


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## _Maq_ (1 Oct 2022)

Yugang said:


> from @ceg4048 post, Rubisco needs typically weeks to adjust.


From another source: Plants routinely renew 15 to 25 % of their proteins daily. [They don't build them from scratch, they re-combine amino acids.]


Yugang said:


> A PhD thesis that studies variations in availability of resources that aquatic plants need for photosynthesis. Special bonus for @_Maq_


I've read it through. No mention about 'adjusting Rubisco for weeks'. It talks about the whole photosynthetic apparatus. Plants permanently adjust it, bit by bit, and "weeks" are arguably a suitable description of velocity of these adaptations.
If you replace terrestrial plants from your apartment to direct sun, you 'burn' them. It takes time to adjust to new light conditions, indeed. Yet I wouldn't go as far as @ceg4048 did to call two-hour light siesta a big mistake. If that would be true, than any change in clouds and shadows in nature would have to be considered a deeply stressful factor. Obviously, it is not.
I think we should attempt to keep conditions (CO2, lighting) as regular as possible in the range of weeks and months. Regular does not mean constant during 12 h or 24 h periods.


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## JoshP12 (1 Oct 2022)

Hi all,

What a lovely thread!

Just saying: I don’t buy into the rubisco thing, nor the stability.

Anyways, here is my most recent thoughts on the topic for the OP (just to throw a wrench into the discussion):
Post in thread 'A reflection - putting it all into one scape'
A reflection - putting it all into one scape

The advice is fine and will yield success, but it’s not gospel. 

If I was a plant, I wouldn’t be regulating rubisco for free co2 in water … what if the water level drops and I get access to air?

@Chrispowell stay the course with the profile and stability etc - it will work!


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## Chrispowell (1 Oct 2022)

Thanks for adding to this great thread!

I just read through your journal and even if some of it went over my head I will like the ideas and results! 

My tanks looking better, plant growth is improving and the only remaining algae is some hair on moss and bolbitis/buce.

I have a theory that this will go with a greater healthy plant mass? This is my next journey anyway.. 

Thanks 

Chris


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## Yugang (2 Oct 2022)

_Maq_ said:


> I've read it through. No mention about 'adjusting Rubisco for weeks'.


Agree, I did not claim that this was covered in the attached thesis.

       I did some literature search, searched on other fora as well, and summarised my findings in a previous post.



Yugang said:


> It seems impossible to make scientific statements that are true for all aquatic plants, or even to all plants in our tank. Every plant is different when it comes to adaptation to dissolved inorganic CO2, and Rubisco is only a part of the story.





Yugang said:


> more science does not necessarily help for our hobby.





Yugang said:


> Some of the leading scientists, from what I found and interpret, are Tom V Madsen, Stephen Maberly and George Bowes. Now George Bowes happens to be one of Tom Barr's professors, Tom speaks highly of him, and I suspect that Tom driving the importance of Rubisco and CO2 stability is at least influenced by the scientific community around G Bowes.





_Maq_ said:


> I think we should attempt to keep conditions (CO2, lighting) as regular as possible in the range of weeks and months. Regular does not mean constant during 12 h or 24 h periods.


Actually I had the same hypothesis, and tried to find a scientific basis. I could not find that in literature, but my best guess/understanding was summarized:


Yugang said:


> Now any adaptation to a changing environment means that the plant has to invest in its machinery, and that comes at a cost. It seems that the CO2 stability in our tanks is to minimize these adaptation costs, for any plants - whatever the mechanism is for that particular species. True, lakes and rivers have variations of dissolved inorganic carbon, but we choose pragmatically to make our tanks a good home for each species and at a minimal avoidable cost of continuous adaptation.



From a practical standpoint, it is a well accepted wisdom among successfull high tech tank keepers that CO2 stability is important. As always there may be hobbyists who challenge this assumption, but these include some who do not inject CO2 at all, and/or have no evidence of successfull high tech tanks.

EDIT: Interestingly most hobbyists focus on CO2 stability during a one-day photoperiod, while I intuitively would agree with @_Maq_ that medium term (day-to-day) and long term (week-to-week) stability may be even more important. I reached out to some of the best experts/scientists some time ago, but so far have not got a conclusive insight.


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## Yugang (2 Oct 2022)

Chrispowell said:


> only remaining algae is some hair on moss and bolbitis/buce.


CO2 may be the root cause of this, amongst others. Perhaps still some room for improvement?
Greenaqua even says' All thread algae are indicating low- or fluctuating CO2 levels!' in their algae guide. They have some credibility.








						The Ultimate Algae Guide
					

Algae Guide - comprehensive information on all types of algae, surface scum, milky water and other fishtank problems. Staghorn, black brush, blue-green, green dust, thread, hair, brown and other algae. Diatoms and other bacteria.




					greenaqua.hu
				



I can confirm this from personal experience with hair algae when experimenting with CO2.



JoshP12 said:


> Just saying: I don’t buy into the rubisco thing, nor the stability.


You do amazing things with your tank, don't use any drop checker or pH probe, have your plants pearling 6-8 min after lights on.  Other  hobbyists however may be looking for possibly fail safe solutions, to maximize their chances for success. One shortcut to success is to copy others who are successfull, and the best of them happen to emphasise stability and flow.


JoshP12 said:


> The advice is fine and will yield success, but it’s not gospel.


True. Also in nature plants survive/thrive under remarkable challenges, including huge pH/CO2 swings.


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## Chrispowell (2 Oct 2022)

Maybe a second diffuser on the other side of the tank?

Increase flow further?! 

Different diffusion  method?

Start co2 earlier? 

I best get back to work 😂

Thanks 
Chris


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## Yugang (2 Oct 2022)

Chrispowell said:


> I believe co2 is now on track.
> 
> 100% degassed aquarium water is ph 7.68.
> 
> Now at lights on we are at 6.66 and this drops tp 6.65 by the end of the lighting period.


Almost too good to be true, just 0.01 pH variation during the photoperiod. If anything to be improved from here, it would be to check on flow and distribution. Otherwise, consideer to write an tuturial on this site how to stabilise pH to within 0.01 



Chrispowell said:


> only remaining algae is some hair on moss and bolbitis/buce


it all depends how much algae you have. Very few have ever achieved a perfect algae free tank, and at some point good is good enough.


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## Chrispowell (2 Oct 2022)

Here's some images


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## JoshP12 (2 Oct 2022)

Yugang said:


> You do amazing things with your tank, don't use any drop checker or pH probe, have your plants pearling 6-8 min after lights on.


I actually had to incorporate them lately . And thanks friend.


Yugang said:


> Other  hobbyists however may be looking for possibly fail safe solutions, to maximize their chances for success. One shortcut to success is to copy others who are successfull, and the best of them happen to emphasise stability and flow.


Most absolutely and this is why I urged the OP to stay the track. But they don’t work because of stability or rubisco.



Yugang said:


> True. Also in nature plants survive/thrive under remarkable challenges, including huge pH/CO2 swings.


And we don’t need to subject our tanks to the craziness of nature. 

The stable piece is important but only when the plants are stable-y photosynthesizing. 

Appreciate where you’re coming from and how you support the OP.


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## Chrispowell (3 Oct 2022)

Another question all 😂😂

To test the theory that flow could still be inadequate could I add the wave maker back in or can too much flow be detrimental (currently not live stock).

Thanks


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## chvvkumar (3 Oct 2022)

Chrispowell said:


> Another question all 😂😂
> 
> To test the theory that flow could still be inadequate could I add the wave maker back in or can too much flow be detrimental (currently not live stock).
> 
> Thanks


I am running a Nero 3 in my 40 gallon tank and I have it near 70%. It does blow some plants around and is a LOT of flow but my plants and fish don't mind. Only issue is because this littlep ump moves so much water, I have to keep the back covered with a 3D printed guard. Otherwise some of my smaller fish might get sucked in and get chopped up.

As long as the fish and plants are happy, my opinion is you can never have too much flow.


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## Chrispowell (5 Oct 2022)

Minus the hair algae, are these buce still unhappy?


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## Chrispowell (29 Oct 2022)

Question all.... 

If ph drop in the first hour of co2 on is 0.5 can I calculate that the ph will drop at the same rate for the next hour?

I.e. 2 hours = 1.0ph drop?!

Will that rate slow as the ph drops or remain constant?

Thanks 

Chris


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## Hufsa (29 Oct 2022)

Chrispowell said:


> If ph drop in the first hour of co2 on is 0.5 can I calculate that the ph will drop at the same rate for the next hour?
> I.e. 2 hours = 1.0ph drop?!
> Will that rate slow as the ph drops or remain constant?


Its definitely not constant, it would be really nice if it was though 😄
I dont know the right english words for it but the laws around gas in water are more exponential than they are linear. 
The more CO2 you have in the water vs the air above the tank, the more the rate of offgassing will be. 
The sides want to be similar if that makes sense, and the bigger the difference the faster the exchange will be.
Apologies to the experts if I have chosen incorrect words, sometimes the language barrier becomes a bit difficult.

Unfortunately you must measure the entire ph profile and tune it in the hard way 🙂


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## Chrispowell (29 Oct 2022)

Nope that's a perfect response! Thanks!


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## Chrispowell (8 Dec 2022)

Morning all,

Thought I would follow up but also ask advice once again.. 

So plant health is really good now, missing compounds were added to my fertiliser or front loaded and plants looks really healthy... I'm pleased.

Co2 must still be off, ph drops from 7.6.. to 6.5.. by lights on but then continues to drop throughout the photo period - I'm really struggling to get a stable pH.. any tips?!

Hair algae is persistent is this because the ph is continually dropping during lights on?

Any help appreciated 

Chris


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## Wookii (8 Dec 2022)

Chrispowell said:


> Morning all,
> 
> Thought I would follow up but also ask advice once again..
> 
> ...



How much further is it dropping through the photo period?

Generally increased surface agitation is the answer, this will off gas more CO2, so you may have to up your injection rate to compensate (and may be able to reduce your build up period before lights on as a side benefit), but it helps create a harder ceiling for the CO2 and results in improved stability in the CO2 levels.


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## Chrispowell (8 Dec 2022)

At the moment it gets down into the 6.3..

I have added a wave maker and at 14:00 when I lights come on today I will play with surface agitation and see if I can reduce the drop


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## Wookii (8 Dec 2022)

Chrispowell said:


> At the moment it gets down into the 6.3..
> 
> I have added a wave maker and at 14:00 when I lights come on today I will play with surface agitation and see if I can reduce the drop



I'm not sure I'd be too concerned about a 0.2pH difference - the wave maker might be overkill, I'd just maybe raise the lily pip a little.


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## Chrispowell (8 Dec 2022)

Wookii said:


> I'm not sure I'd be too concerned about a 0.2pH difference - the wave maker might be overkill, I'd just maybe raise the lily pip a little.



Hmmmm, so the hair algae is not caused by a dropping pH?


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## Wookii (8 Dec 2022)

Chrispowell said:


> Hmmmm, so the hair algae is not caused by a dropping pH?



I'd say its unlikely - 6.5pH to 6.3pH over the entire photo period isn't much of a variance. 

Do you have a picture of the hair algae? Green hair algae can be difficult to deal with, because it operates much like higher plants. Do you still have your Twinstar at 50%?


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## Chrispowell (8 Dec 2022)

The light is on roughly 75%, drop checkers green come lights on and green/yellow at lights out 

Hair algae keep coming back..


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## Wookii (8 Dec 2022)

[22/09/2022]:


Chrispowell said:


> Twinstar 900S turned down 50%





Chrispowell said:


> The light is on roughly 75%



So you've increased the light by 50%? In my limited experienced green algae are predominantly triggered by excess light, and the Twinstar 900S is quite a bright unit - even at 50% its still putting out 2625 lumens,

Was there a specific reason why you decided to increase the light output?  I would try reducing the light back down to 50%, and stay on top of the algae via manual removal with a toothbrush, and see if its growth reduces after a few weeks.


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## Chrispowell (8 Dec 2022)

I agree, the light is the driver.
 However my theory was why turn down the light when I should be optimising conditions for the light at full brightness? 

The tank looks dim at half brightness and I thought It would be more beneficial to learn how to overcome the issue then reduce the light and not learn how to balance the conditions. 

Many use this light at full power so I beat myself up not knowing how...

Thanks for the pointers so far though 

Chris


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