# CO2 by feel



## JoshP12 (24 Jun 2020)

Hi all,

Ok, it seems that now that my plants are growing very well, all I can do is question all of the "things" I did to get it to work well.

I used the pH profile, I got it stable, I inject 4.5 hours before lights on to get the drop, I have dual DC to cross reference CO2 (it seems to be 35 ish not 40 like I said in a previous post - but its all guess work).

I am slowly increasing my light for fun to see what will happen to the system.

Does anyone do CO2 by feel? If so, can you explain to me how you do it? 

I would say that feel means that you do not chase pH stability and do not chase DC color; simply put, you watch plants and adjust.

Josh


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## Zeus. (24 Jun 2020)

Think quite a few folk who have been doing CO2 injection for years do it by feel/experience. The most important thing to watch is the plants after all.

The pH probe and DC are just very useful tools to check [CO2] & stability, quick and easy to use/do. Do you need 40ppm CO2 or will 20ppm CO2 be enough. I have recently changed my injection rate from DC light yellow to green and plants are fine. I do have a lower light intensity. All because I ran out out CO2 during lockdown. CO2 lasting much longer as well, 6.5Kg normally last about 30days and been 42days since CO2 was back on and still at 1000PSI main pressure


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## JoshP12 (24 Jun 2020)

Zeus. said:


> Think quite a few folk who have been doing CO2 injection for years do it by feel/experience. The most important thing to watch is the plants after all.
> 
> The pH probe and DC are just very useful tools to check [CO2] & stability, quick and easy to use/do. Do you need 40ppm CO2 or will 20ppm CO2 be enough. I have recently changed my injection rate from DC light yellow to green and plants are fine. I do have a lower light intensity. All because I ran out out CO2 during lockdown. CO2 lasting much longer as well, 6.5Kg normally last about 30days and been 42days since CO2 was back on and still at 1000PSI main pressure



Thanks Zeus! 

But how do they determine (and I hope one who does can weigh in) when to turn the gas on. 

In the future, without running a pH probe, how would I know that I need 4 hours of pre light co2 time to get stable? Or is stability of co2 just thrown to the way side if you turn the gas on one hour before and just slowly turn up injection rate as needed? And observe that the plants are just fine. 



Josh


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## Zeus. (25 Jun 2020)

JoshP12 said:


> But how do they determine (and I hope one who does can weigh in) when to turn the gas on.



Having twin injection/solenoids/timers makes it very easy to do and understand IMO/IME

1. Find the injection rate that yields a stable pH at the [CO2] your after. (I use just one injection for this.)

2. Do NOT adjust the injection rate again, as it will no longer be stable or the same [CO2]

3. Just time how long it takes to reach the target pH - DONE    if its four hours its four hours it will vary from tank to tank and injection method to injection method


I am able to drop the pH very fast in about 20mins to DC pale yellow as I have the second injection on for pH drop only (needle valve being fully open on this line)


I have a crazy BPS


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## JoshP12 (25 Jun 2020)

@Zeus.

I actually used your strategy to meet with success - it works - and I am thankful for you sharing it with me.

In my area, many people use pH controllers (which is a conversation on its own, and I don't think I'd feel comfortable using one) - but this does theoretically give a "stable" pH before lights on seeing as they run them all day.

I just wonder if someone else who does CO2 by feel could achieve the exact same product with my tank but doing it differently. If so, how is that approach different and WHY do both work.

Josh


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## Zeus. (25 Jun 2020)

JoshP12 said:


> many people use pH controllers (which is a conversation on its own, and I don't think I'd feel comfortable using one) - but this does theoretically give a "stable" pH before lights on seeing as they run them all day.



I have/had one integrated into my PLC, as soon as the signal was off my second line was off for rest of day. Which is fine as long as you calibrate your probe frequently.  But pH controllers don't yield stableI [CO22] IMO, they have pHs going up and down all CO2 on period, and if you don't calibrate the probe the target pH is changing also. 
There is no perfect way for the plants, but the plants can adapt but that may cost energy and result in plant melt/pin holes etc  The more stable your tank the better it is for the plants


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## JoshP12 (6 Jul 2020)

So, I hate to bring this thread but back I made a new realization.

I suspect that most people who are doing CO2 by feel have ample amounts of surface agitation. Since I use a pH probe to constantly track my pH, I can see the change in real time which <has very little lag>.  With high surface agitation comes high injection rates comes fast depresses in pH. Within 15-30 minutes, very little time, I could see my pH stabilize.

So, in response to my original statement:  I would say that feel means that you do not chase pH stability and do not chase DC color; simply put, you watch plants and adjust. 

Is that, with high surface agitation, we need not worry about stability or chasing pH because the high injection rate and off-gas rate forces that.

... I gather (and I will test this soon), but 1-1.5 hours before lights on is really all you will need: given enough surface agitation and a high enough injection rate, the pH will drop and will be stable at lights whether you like it or not.

Josh


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