# CO2 at night?



## Grasshopper (Sep 7, 2010)

So do you leave the co2 on at night or turn it off? I have a 46g tank with injected co2. I currently have it on a timer set to go on an hour and a half before lights on and off an hour and a half before lights out. Drop checker lime green for this time. I am having big problems with bba on my driftwood and also some staghorn and rhizoclonium on the plants:icon_cry: I EI dose and am starting to use excel which I didnt before. I had two bulbs 39w t5ho on for 12 hours and the other two for 2 hour burst at the same time. lowered the first two to 8 hours a day and the other two for a 3 hour burst at the same time. My question is I read alot about fluctuating co2 levels which is one thing that can cause algae and was wondering if leaving it on 24/7 would help? I have the sys. on a ph controller as well! I appreciate the advice cause this algae is driving me NUTS!!!


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## reignOfFred (Jun 7, 2010)

I keep mine on 24/7 but have an aerator turn on and disperse the co2 during lights off. This fluctuating co2 has cause no problems for me or my fish - in fact, now that I've reduced lighting to manageable levels and the photoperiod to just 8 hours, I haven't had any algae issues at all.


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## SuperWen (Mar 24, 2011)

Co2 while lights off? It wont be a problem. But I prefer to turn off co2 while lights off using solenoid regulator, only for saving my co2 stock


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## daverock1337 (Jan 17, 2011)

i rin mine 24/7 right now because i don;t have a solenoid yet, and i have no problems. i'm still adjusting my photo period. i have bba on my df also. right now running 65 watts pc for 10 hours and 55 watts pc for 6 hours in between. i might be switching to 8 and 4/


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## DarkCobra (Jun 22, 2004)

Depending on how far above the tank the lights are mounted, and reflector design/efficiency, the light burst may be exceeding the max photosynthetic limit for the plants. Light in excess of that doesn't help anything but the algae.

Stay with the current 8 hour photoperiod for now.

Verify your CO2 is really at 30ppm or so during lights on, preferably with a drop checker, to double check your controller settings and probe accuracy. Make sure adequate flow is present, especially at the areas where you're having algae problems.

You will see different opinions on CO2 at night, none of which really predict if it's necessary to help eliminate algae in _your tank specifically_. So I invite you to simply try it instead. Put an aerator on a timer and run it at night, not so much to drive off CO2 (the controller with compensate anyway), but to add oxygen; this may not be necessary either, but it's a sensible precaution to eliminate the possibility of oxygen depletion.


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## Steve001 (Feb 26, 2011)

Grasshopper said:


> So do you leave the co2 on at night or turn it off? I have a 46g tank with injected co2. I currently have it on a timer set to go on an hour and a half before lights on and off an hour and a half before lights out. Drop checker lime green for this time. I am having big problems with bba on my driftwood and also some staghorn and rhizoclonium on the plants:icon_cry: I EI dose and am starting to use excel which I didnt before. I had two bulbs 39w t5ho on for 12 hours and the other two for 2 hour burst at the same time. lowered the first two to 8 hours a day and the other two for a 3 hour burst at the same time. My question is I read alot about fluctuating co2 levels which is one thing that can cause algae and was wondering if leaving it on 24/7 would help? I have the sys. on a ph controller as well! I appreciate the advice cause this algae is driving me NUTS!!!


It's probably not a remedy for excess algae in tanks. In natural aquatic ecosystems CO2 is always present. 
I've run pressurized CO2 constantly for close to 20 years and have had algae at times. It goes away. Keep in mind there's a constant competition between vascular plants and simple single cell plants; simple plants get the upperhand I think because it's easier for them utilize the nutrients to reproduce. Whereas multicellular vascular plants have to make specialized cells which takes longer to accomplish. Couple this with having to few plants growing will leave any unused nutrients available for algae.

It's good idea that you cut down on the day length. Rarely if at all do plants in the wild experience full light constantly. That may be a contributing variable.

Let us know how it goes


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## oscarsx (Mar 15, 2011)

I run my DIY 24/7 (because It's my only option without the bottles going POP!) :x


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## takadi (Dec 13, 2010)

I shut off my co2 because I'm cheap and want my cylinder to last a year instead of 6 months.

As long as the ph is relatively stable and there is oxygen in the water, you really can't have too much co2


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