Co2 On 24/7? Airstone At Night?


Jul 24, 2020
Mumbai, Maharashtra, India
Many times solenoids have failed and killed everything, maybe im not lucky. Im getting into planted tanks again after a gap of 3-4yrs, and planning to run co2 24/7. My tank is 24x24x18"H. Here is my plan:

1) 1-bps 24/7
2) lights on for 6hrs full intensity (5-11pm), as my tank is close to window which gets indirect sunlight most of the day
3) from 11pm 7/8am i keep an airstone on.
4) will be using a co2 checker

Not worried about co2 waste, as it better than malfunction of solenoid.

Would this be ok??

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Aug 23, 2018
I run my CO2 24/7 and see no significant change in pH, night or day. There are some plants (CAM) that store CO2 in the dark (they don't all use O2 at night). So, I let CO2 run day and night to benefit my Dwarf Sag (a CAM plant) and to maintain pH at a stable level below 7.0. I also have noted that running CO2 24/7 uses less total CO2 to maintain the same CO2 level. As soon as ambient light enters the room in the AM, plants can begin photosynthesis. Having said all of this, I've also run on a timer and see no large difference between the two in plant performance but, since I use less CO2 with 24/7 and other issues, I see no reason to revert to timing the CO2 - nature doesn't do it.

There are subtle issues that, I believe, are also helped and it is all mainly about maintaining stable parameters. These are beliefs that I have based upon many things.
- preventing ph from rising above 7, as it would at night in my case, prevents possible additional stress on my fish due to NH4 changing to NH3.
- algae love unstable CO2, especially BBA (water changes are a little scary, but I do them because the benefits outweigh the risks and I do them during the siesta). If my pH moves half a point twice a day, that’s about a 20ppm move.
- conversely, plants don’t like unstable CO2 and, therefore, may be slightly weakened.
- nutrient uptake is optimal in the mid 6’s, pH wise.
- chelated minerals may oxidize and precipitate out, making them unavailable to plants during the day.

I wouldn’t focus on bps. Target a 1-point pH drop from fully degassed tank water (let a sample sit out several days) to fully gassed tank water. You can then increase the CO2 further, if you think it is beneficial, but slowly to adapt your fish.