# CO2 Dosing - 0.6 Drop / Yellow Checker



## Zervais (18 Aug 2021)

Hello all,

I have recently invested in a co2 system and have been tweaking it to get the levels right in my system. The issue I have is that I can only achieve a 0.6 PH drop and even this is causing my drop checker to go yellow towards the end of the day. My PH starts at 7.2 at 9:30am when my CO2 is turned on. The lights begin to come on at 10:30am and finish their ramping at 12pm, by which time the PH is 6.6. A few hours later my drop checker will be yellow and the PH has dropped to 6.4, which still isn’t a full 1.0 drop. I’m very reluctant to be adding in even more co2 as towards the end of the day I can see the fish becoming lethargic and breathing a bit harder, not gasping at the surface though.

My tank is 200L, set at 26c, GH is 10, KH is 8. The lighting is a Fluval plant 3.0 at 100% running from 10:30 to 6pm with a 1.5 hour ramp up and down. I am dosing Tropica Specialised Nutrition daily and Seachem Flourish once a week. Many of the plants are new and probably haven’t rooted yet but I wanted to give them the best start possible.

Plants are:
Eleocharis Acicularis
Ludwigia Repens Rubin
Aponogeton Longiplumulosus
Vallisneria Spiralis
Nymphoides Hydrophylla
Staurogyne Repens
Microsorum Windelov
Pogostemon Helferi
Anubias Nana
Lagenandra Meeboldii ‘Red’
Hygrophilia Corymbosa 
Cryptocoryne Undulata
Cryptocoryne Wendtii


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## Zeus. (18 Aug 2021)

A yellow DC is over a 1.0pH drop
I have two tanks one always degas at night the other never fully degases, your 0.6pH drop from CO2 on to  lights on isn't the drop we are need to 30ppm CO2 , its the pH change from a full degassed tank. The easiest way to get the stating pH is take a clean glass rinse it in tank water then fill it with tank water and leave it 24 hrs, then take pH of water in glass, then you have you starting pH, minus 1.0pH which will be your target pH which you need to hit for lights on.
Also you mention your pH drops a further 0.2pH a few hours later, so its still dropping after lights on, ideally we don't want any further pH drop after lights on but getting it completely stable from lights on till CO2 off is very hard, I use a 0.1pH drop from lights on till CO2 off as my goal and call it stable.
Once stable don't touch the injection rate again, just time how long it takes to get your pH drop - this time can not be changed by adjusting injection rate with single injection/solenoids/timers. You adjust the injection only to get the pH stable from lights on till CO2 off 
30 mins is all the ramp up time plants need before they are ready for the higher intensities and after 4-5 hours of high intesities most plants have had their fill and extended lighting is mainly for viewing which also gives aglae its chance to take advantage of the longer lighting periods.


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## Zervais (18 Aug 2021)

Zeus. said:


> A yellow DC is over a 1.0pH drop
> I have two tanks one always degas at night the other never fully degases, your 0.6pH drop from CO2 on to  lights on isn't the drop we are need to 30ppm CO2 , its the pH change from a full degassed tank. The easiest way to get the stating pH is take a clean glass rinse it in tank water then fill it with tank water and leave it 24 hrs, then take pH of water in glass, then you have you starting pH, minus 1.0pH which will be your target pH which you need to hit for lights on.
> Also you mention your pH drops a further 0.2pH a few hours later, so its still dropping after lights on, ideally we don't want any further pH drop after lights on but getting it completely stable from lights on till CO2 off is very hard, I use a 0.1pH drop from lights on till CO2 off as my goal and call it stable.
> Once stable don't touch the injection rate again, just time how long it takes to get your pH drop - this time can not be changed by adjusting injection rate with single injection/solenoids/timers. You adjust the injection only to get the pH stable from lights on till CO2 off
> 30 mins is all the ramp up time plants need before they are ready for the higher intensities and after 4-5 hours of high intesities most plants have had their fill and extended lighting is mainly for viewing which also gives aglae its chance to take advantage of the longer lighting periods.


This is very helpful and I’ll get a glass tonight and test tomorrow to see what my PH is supposed to be. So I need to get a full 1.0 PH drop from co2 to start of lights coming on, right and too much injection rate will cause the PH to continue dropping. You’d also recommend I do a ramp up of 30 minutes, which I can do. Would you recommend I only run my tank for 5 hours at 100%? So say 12pm to 5pm? What about viewing at night? Is it okay to leave on a very low blue/red mix (5% blue, 2% red) until 9pm? This is when I do my most viewing but I much prefer the softer tones when it’s not light outside, so wouldn’t want to do my whole 5 hour stint of lighting then. I suppose I could always do 2pm until 7pm on white and 7pm to 9pm on blue? Does it matter when you add fertilisers to the tank by the way? I usually do it just as the lights come on.


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## Zeus. (19 Aug 2021)

Zervais said:


> So I need to get a full 1.0 PH drop from co2 to start of lights coming on


The 1.0pH drop (30ppm CO2) is regarded the safe optimum level, much will depend on the intensity of the light, the higher the intensity the -
1.higher the [CO2] is needed to prevent signs of insufficient CO2  Or-
2. Better flow is required in the tank to supply/replenish the CO2 at the plants
or a mix of both. Many folk run the pH drop at less than 1.0 and other much higher, I was doing a pH drop of 1.4ph at one time and the DC was nearly clear which was the limit of the livestock at the time. Above 1.0pH needs great care as you can soon kill all the inmates of tank.

A stable pH/[CO2] is the main goal from lights on till CO2 off



Zervais said:


> Would you recommend I only run my tank for 5 hours at 100%?



Yes and No, there are guidelines which need give a rule of thumb, light 'A' may be so intense that 5 hours is plenty, where as light 'B' may need 6 hours for plants to have their fill, also how deep the plant is in the tank and type of scape, much is trail and error in slow steps allowing 4-6 weeks when changing things to see how the plants react.



Zervais said:


> What about viewing at night?



Extended viewing is only for our pleasure once plants have had their fill, it happens to be one of my favourite times for viewing also with dim lights and shimmer. However extended viewing with low light also enables algae to advantage of light levels plants are unable to use. So a bit a common sense is needed, bring the on time forward reduce the low intensity time so it suits and see how you get on with the algae.

Also watch out for natural sunlight hitting tank as the suns position changes over the seasons, all it takes is a bit of carboard to block out the unwanted light, not always the most attractive much to my wife's distaste 😅


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## Zervais (19 Aug 2021)

Zeus. said:


> The 1.0pH drop (30ppm CO2) is regarded the safe optimum level, much will depend on the intensity of the light, the higher the intensity the -
> 1.higher the [CO2] is needed to prevent signs of insufficient CO2  Or-
> 2. Better flow is required in the tank to supply/replenish the CO2 at the plants
> or a mix of both. Many folk run the pH drop at less than 1.0 and other much higher, I was doing a pH drop of 1.4ph at one time and the DC was nearly clear which was the limit of the livestock at the time. Above 1.0pH needs great care as you can soon kill all the inmates of tank.
> ...


So I tested the glass of water and it comes out at 7.9 (did a liquid ph test kit and recalibrated my pen and it came out the same). Is this right though as my tank has never tested that high in PH before, and I even recently changed to 50% RO water. It’s not even this high out of my tap! I’m a little worried as I have soft water species (Apistogramma and zebra pleco) and if my PH goes up to 7.9 every night, will that affect them? I understand I need to get it down to 6.9 before my lights come on, then keep it at that until my lights go off. I just want to make sure that’s right.


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## Zeus. (20 Aug 2021)

Sounds like you have rocks with CaCO3 in them and they are dissolving in the tank water and increasing the water hardness and pH at the same time, @wooki had this happen in his tank as well. If you take a rock out of tank and drop a weak acid on them if they have CaCO3 the acid will bubble on the rocks, if it acid does nothing they have no CaCO3


Zervais said:


> I’m a little worried as I have soft water species (Apistogramma and zebra pleco) and if my PH goes up to 7.9 every night, will that affect them?



its not its- 


Zervais said:


> My PH starts at 7.2 at 9:30am when my CO2 is turned on



So it doesn't loss all it  CO2 overnight- some tanks don't, you may notice your DC doesn't go dark blue also.

do the fish seem to be distress before CO2 comes on? I have never kept soft water fish so dunno


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## Zervais (20 Aug 2021)

Zeus. said:


> Sounds like you have rocks with CaCO3 in them and they are dissolving in the tank water and increasing the water hardness and pH at the same time, @wooki had this happen in his tank as well. If you take a rock out of tank and drop a weak acid on them if they have CaCO3 the acid will bubble on the rocks, if it acid does nothing they have no CaCO3
> 
> 
> its not its-
> ...


I’m using seriyu stone but I’ll definitely try the acid method once I can get a hold of some. They’ve only been in there for two weeks, would they really cause this much of an issue? I also have a ton of new wood in there which you would have thought would bring down the PH. I wouldn’t necessarily say they look stressed but I did notice one apisto breathing a little heavier, I’m not sure if that’s an issue or not. Perhaps I’m just looking into things too much there. I did a test with my pen and liquid test kit this morning and the water is 7.7 with a pretty strong blue on the drop checker. This was after adjusting yesterday, so I’m now going to see if I can get it to drop to 6.7 and stay there. If the drop checker goes yellow I know that I should be aiming for 6.9, but if not then I’d be happy with 6.7 for now.


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## Zeus. (20 Aug 2021)

Zervais said:


> I’m using seriyu stone



Its loaded with CaCO3.


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