Clive,
from what I've been told it's 8 mg/l is the equilibrium level for water (of course this depends on temperature and altitude etc), but let's take that as our figure to work with. So no matter how much splashing around one does, this level cannot be increased since it's the equilibrium level. Is it true that planted aquariums can shoot that level over 10 mg/l, plants would be a different matter since they are injecting the water with O2?
From Simon's setup all I see is a closed sump. To me, it's basically a canister filter with an easier cleaning arrangement, but you do have the water surface of it that is in constant motion that contributes to the gas exchange if a difference occurs. Most of the vigorous splashing around might come from the feed if there is gurgling there.
What I want to ask is if it's worth the while to get a trickle tower involved. It's a more potent form of biological filtration since the bacteria will take the oxygen from the air and not the water. BUT, if the water is already saturated to over 10 mg/l by the plants, oxygen will get degassed from the water in the process along with CO2 if we have to inject the tower with air (which we do to make the tower work effectively, if we seal it, it just acts like a submersed filter).
Your sump is therefore out-gassing both of these gases until each reaches their independent equilibrium concentrations. Oxygen has a lower equilibrium concentration than CO2. So really, your sump, if exposed to atmosphere is acting as a vent. Ideally, you'd want the sump sealed against atmosphere until the concentration of O2 fell to at or below atmospheric equilibrium concentration level. Only then would it actually add O2. Since there is no inexpensive way to monitor and control this, I would seal the sump and leave well enough alone. You want to delay the out-gassing of CO2 because this makes it easier to get the CO2 levels up to optimum levels before lights on. The penalty is that O2 levels may fall below equilibrium levels - but higher CO2 levels will enable the plants to more easily replace the O2.
from what I've been told it's 8 mg/l is the equilibrium level for water (of course this depends on temperature and altitude etc), but let's take that as our figure to work with. So no matter how much splashing around one does, this level cannot be increased since it's the equilibrium level. Is it true that planted aquariums can shoot that level over 10 mg/l, plants would be a different matter since they are injecting the water with O2?
From Simon's setup all I see is a closed sump. To me, it's basically a canister filter with an easier cleaning arrangement, but you do have the water surface of it that is in constant motion that contributes to the gas exchange if a difference occurs. Most of the vigorous splashing around might come from the feed if there is gurgling there.
What I want to ask is if it's worth the while to get a trickle tower involved. It's a more potent form of biological filtration since the bacteria will take the oxygen from the air and not the water. BUT, if the water is already saturated to over 10 mg/l by the plants, oxygen will get degassed from the water in the process along with CO2 if we have to inject the tower with air (which we do to make the tower work effectively, if we seal it, it just acts like a submersed filter).