I know flow relates to oxygen, and I should possibly test for oxygen
VaughnH;28135 said:If I am not mistaken, Powerheads were originally designed for use with undergravel filters. They mounted on the water tubes from those filters to lift the water flow from the filter, which required that they produce enough head pressure or suction to do that, which caused them to be made with centrifugal rotors. Over the years powerheads began to be used for other reasons, but their basic design didn't change. The Koralia type powerheads are unique in using a boat propeller to move water, which gives the high flow rate, but zero head pressure, and low flow velocity that we need for circulating water in the tank. And, the Koralia, in particular, is well engineered with its magnetic mount and swiveling head. I think it is a break through design!
Hi Jeremyjeremy v;28585 said:Randolph,
In a natural tank (without CO2 being injected) a powerhead is fine. It will increase circulation, and as long as the surface of the water is not being broken and is not rippling from the powerhead, CO2 loss will be minimal if anything.
The empty HOB filter will lose you some CO2 from the water breaking when it falls back into the tank. Remember though, in a non-CO2 injected tank, all a powerhead, air stone, or HOB filter can do is decrease the water CO2 levels to equilibrium with the air, which is about 2-3ppm. They can't drive the CO2 lower than that, because the air will just put it right back into the water, so if plant growth is really slow a HOB filter or powerhead can actually be slightly beneficial by keeping the tank CO2 levels from going all the way to zero by continually pulling small amounts from the air and maintaining equilibrium.
Most people want plants that grow much faster than that really slow rate though, so that's why they want to boost their CO2 in any way possible. The only way your tank can have higher than equilibrium concentrations of CO2 (without injecting CO2) is by trying to hold onto the by-products of fish respiration and bacterial action in the substrate as well as possible. The more fish you have, and the more decomposing matter/bacterial action there is in the tank, the more possibility you have for higher than equilibrium CO2 levels in the tank. That higher than normal concentration of CO2 is what you risk losing with too much surface agitation, nothing more.
Have a good one, Jeremy