# should I shut off my CO2 at pm?



## donmartinr

Another newbie.
Just wondering, should I turn off my CO2 at night? I read somewhere(can't remember where), there will be more ph fluctuations which isn't good and can lead to more algae.
BTW, I do have a solenoid with my set up.
Thanks


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## Salt

pH fluctations due to CO2 are harmless to fish. Amano has CO2 on timers on all his tanks for switching off at night. I also have mine on a timer to switch off at night. (Not that you should do it "just because a big name does it;" I'm just using that as an example.)


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## hoppycalif

CO2 fluctuations caused by the CO2 being off at night won't make algae grow. What can is letting the lights-on CO2 concentration drop down below 20 ppm thru neglecting to keep track of it. The only advantage to shutting off the CO2 at night, as far as I can see, is that it lets you run CO2 up a bit higher during the day, and letting the fish have a break from it at night. My solenoid valve stopped shutting off a few weeks ago, without my noticing it for awhile, and I ran pretty high CO2 24 hours a day for a few weeks. Nothing bad happened caused by that. (To my knowledge.)


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## yildirim

Unless you don't observe your fishes gasping at the surface for air at lights on time or earlier there is no need to shut it off. pH fluctuations here would not cause a significant problem.


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## Bert H

I run mine 24/7. I tried the solenoid route, but with hard water, as I have, it took too long for the CO2 to come up to adequate levels when I turned it off at nights. If you do run it on solenoid/timer, I would suggest starting it an hour or so prior to lights on in order to have your CO2 levels up there when lights come on.


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## dstephens

I run mine 24/7 also but to hedge against an overnight melt down, I have an air diffuser that comes on about an hour after lights out. Keeps the water well oxygenated. I have had my CO2 equipment go off spec in the night and wake up with fish dead, or at the top of the water gasping for air. On the other hand, I am somewhat of newbie also having been at it for about 7-8 months. But, you can get yourself up to speed very quickly by reviewing different threads on this site and asking questions. There is an amazing wealth of knowledge and experience, combined with friendly folks here who want to help. Anyway, that's how I addrss the issue for now. I know that agitating the water surface with the air bubbles will minimize the effect of the CO2. I do have a question for the viewers here. I understand the plants do put on serious growth at night and if that is so, how does CO2 effect that growth at night, if at all? Thanks for letting me share. Darrell


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## donmartinr

thank you for all the reply!!!!
This site has been a great help esp to newbies like me!!!!


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## Hawkeye

There's two camps here, 24/7 and the CO2 off at lights off. I fall into the 24/7 camp for now. I believe that the CO2 off at lights out is only meant for those that use a PH controller. 

The theory in CO2 off at night is it saves on CO2 and cut down on the PH swing. How ever I have all ways thought this not to be true. One day I ran across a post about this in the Krib. Just as I have thought you have a larger PH swing by turning off CO2 at night then just leaving it on. 

Another pulse to having CO2 24/7 is the zero time to start CO2 saturation and a shorter lights on time. When you turn off CO2 at night the saturation level of CO2 has to build back up before plants will start maximum growth and you see this as pearling in the tank. This time can take as much as 2 hours. When using the 24/7 method, CO2 saturation starts as soon as lights come on. Plants will start growing fast from the start. So this saves at least two hours of lights on time. I run my lights on 8-9 hours. To get the same amount of maximum growth time with the CO2 off at night method I would have to have light times around 10-12 hours.

I run my tanks at 24/7 with CO2 levels at or close 30ppm. I don't have any surface turbulence. Fish are fine. But if you have high levels of CO2 without seeing pearling It could be a problem. Remember! not only do you need to keep a balance with ferts you have a balance with CO2 and the amount of light ( in watts ) you have. This is balanced by the amount of maximum growth time in hours. This will very with the types of plants you have in your tank.

Hawk


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## Glouglou

*No waste, no problem*

My solenoid is on a small timer, start 2 hour before light up, stop one hour before light off.

No waste and all the control I need. You can play with the off and on cycle and bubble count. No need for expensive finecky ph controller.


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## oRiN999

i have two presurized tanks one is on 24/7 and there are no problems that i have seen. my other tank has a ph controller they cost about another $80 and you have to recalibrate them every now and again but it also keeps your fish safe because it can be set to shut off the co2 if the ph get too low


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## John P.

oRiN999 said:


> ... but it also keeps your fish safe because it can be set to shut off the co2 if the ph get too low


One might also say that it gives another possibility of misreadings/malfunction that could cause the demise of your animals.


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## 5380

In my tanks, with the Co2 on 24/7, the PH during lights out is 6.4 and rises to 7.4 over about 2h stressing the shrimp in the tank. The shrimp get a milky coloration to their internals, and kick violently crashing into things, and die. The tank is about 6 gallons total because of all the volume hardscape takes up, and Co2 consumption is all over the place overnight and during the day. With a KH of 6, my CO2 goes from 45ppm to 7ppm. This has resulted in more algae showing up. I see three options to controlling my CO2: Buffering the water with the right carbonate buffers, running the solenoid and shutting off Co2, or buying a controller. 

I wanted to grow high light plants and a few stems but not do more than 10 mins of maintainence each week. PH meters can definately go bad, but they can be tested and calibrated quarterly to make sure they're working. Rather than dealing with algae and dying shrimp, I'm gonna buy a controller and build a reactor for inside the nano cube compartment.


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## mousky

Dont shut your C02 off if you run it off a DIY yeast bottle or it will explode!!!


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