hi,
do you think it is bether to turn Co2 off at night or not?

It's not used at night, having it at high levels when the it's not being used serves no purpose and makes life harder on fish when there's no added O2 from the plantas.

Regards,
Tom Barr

and your co2 bottle will last longer also.

Thank you guys!

Do you turn it back on before the lights come on to get your CO2 levels up when the plants start their daylight cycle? Or is the nightly swing not enough to make a difference?

I currently have mine running 24/7 with no averse effects, besides possibly wasting some CO2 at night...

mine goes on and off with the lights you can set it to turn on a hour before the lights come on so co2 is up to level already when the lights come on but i dont see the need for it.

dschmeh: How much CO2 do you loose in the night time? i.e. Where is your PH driven to with CO2 in the day, and where is it in the morning when the lights come on?

never tested it dont need to plants are pearling like crazy and fish aint gasping at the surface and no algae. Only thing i test is nitrate about once a month to make sure im still on track I use EI Method

I wonder about the PH drop also. When I turn the CO2 off at night my PH will rise from 6.7 to 7.4 by the time the CO2 is turned back on and the PH drops back to 6.7. I am not trying to target a specific PH, but I thought the idea was to avoid PH swings. I do have an airstone that turns on when the lights go out to ensure there is adequate oxygen at night.

Are the nightly PH swings a "don't care"?? Turning the CO2 off at night would be nice since the only thing it does during that time is maintain the PH level.

Thanks for any opinions!

Brian

I used to use an airstone at night but no longer find the need. I bet that some of that large swing you have there is because of the airstone. Try turning the airstone and the CO2 off at night.

I have been told repeatedly that pH swings due to CO2 don't matter one bit.