Part Time HoB

[dbaron]

Im setting up a heavy planted 75g, 4x 54w T5 HO lights, no CO2. Little worried about O2 levels at night. I have a small HoB that I planned on using once in a while for water polishing but now Im thinking about putting it on an opposite timer to the lights for more aeration.

Would I have to worry about the water in the HoB being stagnant for ~12hours? Or just screw it and leave it running all the time and not worry about the extra aeration during the day?

 

[JakeH]

I don't think you need to worry about the O2 if you're not running CO2. If its heavily planted, you actually want to avoid aeration or your plants won't grow very well. If you just insist though, make your "part-time" HOB mechanical only (no bio-media). Any bacteria that managed to grow while its on would just die off & make more ammonia.

 

[FSM]

There isn't any reason to turn it off. On my 75 gallon heavily planted I run 2x54W with CO2. There is a decent amount of rippling at the surface from the canister filter spray bar output.

If its heavily planted, you actually want to avoid aeration or your plants won't grow very well.

You're wrong. Aeration doesn't reduce the dissolved CO2 concentration below equilibrium with air, which is where it will be unless you diffuse CO2 gas into the water.

4x54W is way too much light though, even if the reflectors aren't very good (ie odyssea type fixtures)

 

[Noto]

I agree with FSM. Run that puppy 24/7 for best health of both fish and plants.

 

[schaadrak]

If your not running CO2, leave it on all the time. With that much light in a heavily planted tank it might actually help replenish CO2 levels in the tank, though only slightly.

You should look at CO2 in the future, though. You've got close to 3WPG of HO T5 with lots of plants. CO2 is going to be used up pretty quickly.