HOB filter on a timer...

Are you injecting Co2?

The AC filters have an adjustable flow rate if you want to decrease surface agitation...

I can't really afford to inject Co2. I'm just dosing every other day with Flourish Excel. The plants are growing well, but I feel they would do better with some Co2. Doesn't surface agitation release Co2, that my tank naturally produces, out of the water?
 
Like I said, your plan won't work due to the limitation of the equipment; any other details are superfluous at this point.

You can also attach a piece of filter foam to the HOB's outflow to diffuse the water and minimize surface disturbance. If you want some night-time oxygenation, add an airstone and put that on your timer.

My filter seems to stay full after I unplug it. Same with my Aquaclear 110. It only drains itself when I siphon water out of the tank itself.

Thanks for the advice by the way! I think I'm going to try that...
 
Ah, you must keep your tanks filled to the brim. I always keep my water level a little bit low, so my filters drain when unplugged.

As far as CO2 goes, the atmosphere contains a far higher concentration of CO2 than your water does (if you are not injecting it), even if the tank is heavily stocked. Therefore surface agitation will actually increase the CO2 levels in your tank (as well as O2 levels).
 
Ah, you must keep your tanks filled to the brim. I always keep my water level a little bit low, so my filters drain when unplugged.

As far as CO2 goes, the atmosphere contains a far higher concentration of CO2 than your water does (if you are not injecting it), even if the tank is heavily stocked. Therefore surface agitation will actually increase the CO2 levels in your tank (as well as O2 levels).

Hmm...that's interesting. I've never thought of it that way...
 
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