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ph readings, dropchecker always green and aquasoil... any relationship?

Hi everyone,

Interesting discussion. Thank you Parotet for starting it and giving such detailed information.

This is something I have been struggling with for a while! A year ago I was also given the advice to try and drop the PH by 1 point by the time lights went on. I was struggling to achieve this so I started the gas 3 hours before and switched it off 3 hours before lights off. However, this nearly led me to gassing all of my fish by the time the lights went out - as surely it is logical that if I can drop the PH by 1 within 3 hours then the subsequent 3 hours will drop it by a further point too? No?

Anyway, this weekend I read the threads about the CO2/PH/KH table quoted on this thread so took a sample of my water to the local Maidenhead Aquatics and they tested it for KH (a good idea Parotet, without any expense!) and they told be the KH was 7.5 (from a sample taken before lights or gas were on, should that make any difference).

PH is neutral at somewhere between 7 and 7.3 but I've not got a very accurate reading of that (my sample of water wasn;t big enough to test both and my kit goes up in .5 increments! doh!)

So, whilst my water is nowhere near as hard as yours, Parotet, it did get me thinking about the buffer zone. If I take the PH to be 7.2 and the KH to be 8 on this table, then surely to get to my target CO2 level, I only atually need to drop the PH to 6.9 to achieve it?

Currently I am dropping to beyond this by the time the gas goes off. Tonight it was reading at about 6.5-6.7 when I got home an hour after the gas had gone off. Which, according to the table is way too much?!

Can somebody please explain why, with this table and my drop checker reading lime green, do I need to drop the PH by 1 before lights go on?

Thanks
Paul
 
PS. Also, can anyone tell me if the PH pen checkers or similar (shown below on ebay) are worth buying? Are they accurate?

I would like to do more detailed hourly tests like Parotet did but I only have a broad colour based test kit (0.5 increments) and my LFS doesn't have anything more detailed. They suggested a cheapish digital one.

LCD Digital PH Hydroponic Pen Meter Pool SPA Aquarium Wine Water Tester Pen UK | eBay
OR
Digital pH Meter Monitor Tester Replaceable Electrode Probe Solution x2 Aquarium | eBay
OR
Waterproof Digital big LCD pH & Temperature Meter Tester 0~14pH °C °F IP65 | eBay
 
Hi Paul! Thank you for your reply. As you have noticed I am not an expert on this topic... 🙂 But this thread has been really interesting to learn and think about some of the things happening in my tank. I will try to explain the lessons I learnt playing with my pHmeter and DC.

Concerning the measures I did, I have to say that I borrow a (very expensive) pHmeter from work. It has to be calibrated before each measure but it gives an accuracy of 0.01. I think a cheap pH meter can be used to measure the trend of your pH, but when the drop is significant (let's say 1 point). Have a look at my graph and you will see that I managed to have maximum drops of 0.5, and some days it was less. That means that if I worked with a pH meter with an accuracy of 0.1 my measurements would have been very bad. So I guess it is a balance between what you are measuring and what equipment you can afford or borrow. The difference between these pHmeters can be very high (from 10 to 3,000 euros), and IMO it makes no sense to spend that money because we have other indicators... DC!

Concerning the pH drop, it was explained by Darrel that the DC is a good estimation of the CO2 based also on pH drop but in an isolated and controlled chamber (the DC), thus what you can read is not affected by other acids in the water column. It really measures the CO2, but indirectly. A pH meter is useful and accurate but you should understand that some of the readings can be affected by humid acids or other substances on the tank... Note that my first reading at 7am is quite different from one day to another, especially now that aquasoil is not leaching that much substances. If KH changes, my pH reading will also be affected... The DC never lies, but it can be hard to read (really confusing sometimes to tell the difference from green, to lime and yellow).

The lesson I learnt is: use the pH meter for example to test which configuration is the best to reach the maximum drop when lights on (where to place the outflow, which kind of outflow, where to place the diffuser, etc.), check with the DC that you have a nice lime green when lights on but also check that it doesn't go yellow (I found for example with higher bps my DC was yellow at the end of the day), and finally don't be confused if you don't manage to reach 1 pH of drop. If your water is too hard, like mine, and if you finally manage to have such a drop you will be adding much more CO2 than needed (you will be gasing your fish. Have a look at the chart and see the CO2 values when dropping 1 point of pH in very hard water...)

Two other very important lessons learnt about CO2 in this forum... Flow and constant levels. If all the leaves in your tank move gently the CO2 gets everywhere (much better than having lots of CO2 in some areas and dead spots). About the amount of CO2 it seems that plants can get used to different levels of CO2 but they have serious difficulties to adapt to changing levels.

Once again, please note that I am just a newbie and these are very basic rules I have learnt and experienced in my tank, but maybe poorly explained.
 
Thanks for your reply and summary Parotet - without wanting to be patronising, you have written an excellent summary and all learnt very fast by all accounts!

My difficulty is that easy growing plants grow well but other ones die within 2 weeks of buying. And everything on here has advised it is about getting the co2/light balance correct. However, on the CO2 front, I did indeed nearly gas my fish in exactly the scenario you described above.

And yet, I don't think my water is particular hard, more soft/medium I would think. But even with this, taking the reading of KH being 7.5 and a starting PH position of about 7.2-7.3, I surely don't need or should be looking for a drop of 1. The important thing to note here is I would have thought very few people should be - unless most tap water has a PH of over 7.5 or most water is medium-hard, in which case large drop in PH is needed but would be very hard to achieve!
 
hudsonpd said:
However, on the CO2 front, I did indeed nearly gas my fish in exactly the scenario you described above.
Click to expand...
Nearly gassing of fish is a result of poor execution of flow and distribution. The effect of good flow/distribution is to obtain a more homogeneous CO2 concentration across the tank. Everyone assumes that any point in the tank has the same CO2 as any other point in the tank. This idea is brought about by the fact that we normally only use a single point measurement in the tank at the location where the DC is mounted. The reading taken by the DC is immediately taken as a proxy measurement for all other points in the tank, and this is a very poor assumption.

hudsonpd said:
But even with this, taking the reading of KH being 7.5 and a starting PH position of about 7.2-7.3, I surely don't need or should be looking for a drop of 1.
Click to expand...
Yes, surely you should. The "Ph-delta" of 1 is just a guide. You may need to drop it more and you may be able to get away with less. But it's a good starting point that seems to work well for a majority.

If a pH drop of 1 in a KH 7.5 causes discomfort or fatality in the tank, then we can immediately conclude that either poor flow or poor distribution, or both, is the likely culprit. That information is based on personal experience and the experience of those who use this technique. Again, people become too rigid when applying, what we consider to be, simple guidelines, often run into conflict because they are not looking at a wide enough picture.

The need for the pH drop has nothing to do with the effects of pH, but rather has to do with the fact that the difference in the pH over the short span of time is mostly due to the effectiveness of the CO2 in dissolving. And it is actually very easy to drop the pH using CO2 in medium alkalinity water that you have.

The point is to forget about pH as a factor in plant or fish health. They really do not care very much about what the pH value is. They only care about WHY the pH is at it's present value. If the pH drop is due to a toxin, then they will suffer due to a toxin, not due to the effects of pH. If the pH drop is cause by an innocuous agent then the fish will not exhibit any aversion to the change in pH. CO2 is a weak acid and is therefore innocuous from an acidic perspective. Strong acids, like the stuff in "pH Down" type products are toxic because they contain toxic acids. A pH drop if 1 unit caused by pH Down type products causes injury to fish - because Nitric or Phosphoric acids are strong acids. Yet, people add these products to their tank all the time trying to "stabilize" or otherwise control pH.


hudsonpd said:
Can somebody please explain why, with this table and my drop checker reading lime green, do I need to drop the PH by 1 before lights go on?
Click to expand...
This is another misapplication of the table. The table cannot tell you how much CO2 is in the water at any one point. It cannot tell you how much of the acidity is caused by CO2 as opposed, for example to tannic acid leached from wood, or due to nitric acid caused by decay of organic substances in the water. Therefore, the value it returns, based on a single point reference is always going to overestimate the actual CO2 content. There can be hundreds of other acids in the tank in very small quantities. They all combine to produce a pH in the tank water. The table assumes that all the acid in the water sample you are measuring is caused only by Carbonic acid which results from dissolved CO2.

In order to jump around this obstacle we take at least two readings and we assume that the DIFFERENCE in the reading is caused only by CO2 dissolving. That's not a 100% fact, but, there is not enough acid being produced by the tank to drive such a large difference. The component of humic, tannic and other organic or inorganic acids that contribute to the pH drop is miniscule when compared to the difference in acidity caused by the Carbonic acid. So by subtracting the pH values, one can then roughly calculate how much CO2 was added, because when you subtract, you are effectively subtracting out the component of tank-produced acids.

parotet said:
Concerning the pH drop, it was explained by Darrel that the DC is a good estimation of the CO2 based also on pH drop but in an isolated and controlled chamber (the DC)
Click to expand...
The DC is NOT a good indicator, but it is all we have, unless we are willing to shell out £1000 to buy a CO2 meter.

It's a LOT easier to use the pH pens, no matter how cheap or cheesy, but as Darrel would no doubt have cautioned, the pens should frequently be calibrated. Because of the fact that this mathematical obstacle of "taking into account the tank-produced acids is eliminated by reading the pH drop" looking at the data, especially when plotted on a graph gives us a very good picture of how the CO2 is behaving and how effective our flow/distribution CO2 dissolution is.


Cheers,
 
As always Ceg, thank for your time and answer

So you are saying I need to take two ph readings in order to work out how co2 is dissolving?

I will take a video at the wake if I can because the flow is good. The dissolving may be an issue I suppose but using an inline diffuser, it has never been really right. It may have clogged up slightly more recently but as I say I don't think co2 has never been quite right. The DC is always green wherever I put it (although it can be hard to see the colour differences)
 
Yes mate, this is the problem with the DC. Of course we have a DC user guide in the Tutorial section and we advocate it's use because it's a very simple tool, but it's just a test kit and we really cannot rely on test kits to have any kind of fidelity.

two ph readings in a span of time tells you what the difference in dissolved CO2 is. So if we take many readings over time, it will paint a more accurate picture of the dissolution during that time. Take a reading starting from when you first turn the gas on. Then, take subsequent readings every hour or even 1/2 hour for the duration of the photoperiod.

What you are looking for is to have the lowest pH "ideally" at exactly the time that the lights go on.

The assumption that the pH will continue to drop to lethal levels is not necessarily correct. That's because the plant will start to uptake CO2 into their tissues and will remove it from the water. Unfortunately, whhen flow and distribution are poor the gas tends to collect/concentrate in some areas, like where the fish are, but the gas is not available way down low where the plants need it most. There can be a difference of gas concentration of 10X from top of the tank to the bottom. So many times, the areas where the fish are swimming has toxic levels of CO2 but the plant beds starve, so fish suffer discomfort while plants suffer CO2 deficiency.

If you can provide a video then that would be great, because then we will be able to see the whole picture and we may be able to point out some things that you might not have otherwise though of.

Also, when you have CO2 issues, a good thing to do is to lower the temperature a few degrees which will help the gas to dissolve better and then the injection rate can be reduced.

Cheers,
 
Hi Hudsonpd, have a look at the readings and figures I made at the beginning of the thread... You need to devote time and you need to be close to your tank to measure the pH every hour, but it is worth it. The best part is that you understand quite well what is happening and why you need to make the changes. The readings helped me to make some decisions on my own, instead of 'following a recipe': to switch on the CO2 earlier, to increase bubble rate, to change completely the outflow system of the tank... Each action was the consequence of a reading.

The problem is that this never stops, I guess... Now my 'worry' is that there is a bit of surface film in my tank. Still poor CO2 availability, too much organic waste produced by a significant growth of plants these weeks, brown diatoms growing on the redmoor... or probably all this together, who knows? But at least this kind of approach to your tank setup gives you a better overview of the problems you may have solved and the ones you still have to face.

And you know what? It is fun. I love to be 'worried' for such things! Don't we keep planted tanks for that? 🙂

Looking forward to watching your video... I also want to check if the movement of my plants is good enough. Regarding the outflow, if it is a spraybar, there is a video anywhere here where you can check what you need to have a good flow.

Cheers,
Jordi
 
Thanks guys. I am pretty sure this is an issue with the diffuser (probably linked to poor maintenance), so last night I installed a new, better inline diffuser which made a huge visual difference - the mist was very fine compared to the other one and less seemed to immediately escape at the top. This is visual only, so I will take PH measurements over the weekend, as suggested to analyse the impact. I think this may save CO2 as well.

I still have the option of increasing flow some more if I need (the filter isn't currently at full power as it was very extreme for the fish) and the trick with the temperature that ceg suggested.

Fingers crossed, but I think diffuser will make a big difference.

Thanks again. I will post back the ph results over the wkd too.

Paul
 
Ok, so I took readings yesterday, although I am only using a standard, test tube-type test, so I'm afraid my readings are all quite difficult to get.

Tank water left out over night was about 7.8
At 11 am (as gas goes on) it was about 7.1-7.3
By lights on at 1pm it was about 6.4-6.5 I'd say.

It then stayed pretty much stable at that all the way through to gas off and then light off - which was 3 hours after the gas went off.

Today, I put the gas on 3 hours before the lights, but I don't think the readings were that much different tbh, which is disappointing. However, it is very hard to get accurate readings with such a test kit! I don't really want to invest in a digital one, just for this at the moment.

Thoughts?
 
Nearly 1.5 drop by lights on looks fine, moreover it is stable during the light period. Further improvement could be done regarding flow to make sure the dissolved co2 gets to all the plants... you have to see them moving gently
But probably you have already done it 🙂
 
Hi everyone, a new update and a short summary of this thread (71 posts! too much reading!):

I got myself this week a CO2 atomizer... and I guess this was definitely the way to go. For the first time I have managed to have significant pH drop before lights on (despite my unknown, but probably very high water hardness... see tap water values above), around 1 point. But much better than this, the pH readings were very stable during the light period and shrimps seem happy with this new situation.

The path followed in this CO2 fine-tuning has been : glass lily pipes and ceramic diffuser in the opposite side > glass lily pipes and ceramic diffuser under the inflow > ceramic diffuser under the inflow and DIY spraybar > atomizer and DIY spraybar
During these changes I increased the bubble rate from 1 to 2 bps.

As a result of all these changes I got more and more significant pH drops, I improved the flow (really ALL the plants in the tank moving), I had a better distribution of the CO2 (atomizer magic mist) and... I hope this will lead my tank to a healthy grow!

At least today I can enjoy my first pearling... 🙂
 
Sacha said:
Reading pH of the tank water is NOT an accurate way to measure Co2.

I have only been on this forum a couple of days, but have seen loads of people talking about their co2 concentration in terms of a pH drop- how much the Co2 drops their pH.

A drop checker is the most accurate way to measure co2 concentration. pH of tank water is affected by so many other things than Carbonic acid. Humic acids, ammonia (which is acidic), nitric acids, even some algaes, all can influence the pH. Therefore we need to read something which is constant and ONLY influenced by the co2 gas (and the resultant carbonic acid). The way we do that is with a contained amount of water of a known KH, which is not in contact with anything else that may alter its pH.
Click to expand...




Still agreeing with this then ???? 😉


Sent from my mobile telecommunications device
 
We have established that measuring pH and KH can not give you an accurate reading of Co2 in PPM.

Measuring pH throughout the day can show you the TREND in Co2 dissolution. But it does not allow you to calculate PPM.

A drop checker is still the best way of seeing if you have too much/ not enough Co2. The pH only tells you what your Co2 is now, relative to what it was earlier, as in- is it higher or lower.
 
Surely we only really need to know what the co2 saturation is from co2 on to lights on as this is the most crucial part and by measuring ph at these points can deliver a better indication of co2 measure then a drop checker located in only one place ??


Sent from my mobile telecommunications device
 
Hi all, well I thought this was finished but it is not. New variables in the equation, new difficulties to overcome...

I have now in the tank some shrimps (Amano and local crystal) and 3 Otos, so new variables to deal with. Some days ago I noticed that my "fine-tuned CO2" was not that good for them. You know what I mean: clumsy movement for fish and shrimps unusually still. When I noticed this behaviour I raised the spraybar to break the surface (bubbles), the DC turned blue in 2 hours and in half an hour everyone seemed happy again.

So, now that I had improved the CO2 solution (atomizer), flow (less filter media and spraybar), CO2 and light timings... and I had managed to have significant pH drops and healthy growing, I found that the CO2 level is not suitable for the new inhabitants.

First question: do they get used to these levels of CO2 or will I kill them slowly?

Then, I guess I have 2 options:

- to decrease the bubble rate: that is what I have done for the moment, but I fear it will damage the plants and my DC when lights on is not lime green but just greenish

- to combine high O2 and high CO2 levels. The spraybar is just on the water line creating some ripples. I have read that some people even break the water surface to have more O2 and to be able to maintain high CO2 levels (in my case, this would mean to keep on working with the previous bubble rate). I guess the DC will turn blue at night (instead of being greenish) but I will be able to have a lime green when lights on thanks to a higher bubble rate. In that case, should I have a nice rippling or break the water surface (bubbles, jets breaking the surface)? I think "Amano followers" do this at night, raising the Lily pipes at night, but changing everyday the spraybar is not a good solution for me... I have also noticed that when I break the water surface the surface film disappears, but I am not sure if this system will degass to much the water column.

Thank you for your feedback in advance.

Cheers,
Jordi
 
Hi Jordi,

I would go for option two, or even for a third option that consists in doing no changes in your tank. I have several Amano shimps, hundreds of Red Cherries and a couple of Ottos with high CO2 injection regime and they all are OK. I also had a shimp tank with DIY CO2 where DC was always bright yellow and shrmps population increased with no problems.

This is just my experience, there are not two identical planted tanks, but hope it will help you

Cheers,

Jose

Enviado desde mi ST25i usando Tapatalk 2
 
Jordi, I run with high surface agitation and as a result pump more gas in, but this is how my fauna like it. It's weird that less gas + less surface movement V. more gas + more surface agitation has that much difference, but it did for me 😉

I'm not breaking the surface with the spray bar but have strong turbulance visible. Just make sure when doing water changes etc that you keep the level stable. I once filled to a cm difference over usual, thus reducing surface movement from what it was, and saw negative results on fauna. So i'm ultra careful now, also keep my filter cleaned every 2 weeks to ensure the throughput of the unit remains consistent and doesn't tail off 🙂

The beauty of this is that once the lights and gas are off the water will oxygenate quicker (thus your DC will return to blue by AM). I hope i'm right in saying that, or that was my observations anyway!
 
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