Question of CO2 and O2.

[Alshain]

I believe I am suffering from a lack of O2 in my tank. I have fish hovering at the surface of the tank.

The problem: Add oxygen to the tank without increasing surface aggitation and decreasing CO2. I have heard that it has been proven that O2 does not displace CO2 and vice versa. If this is true then adding an oxygen pump with a T-Valve to the end of my CO2 generator (just before it enters the reactor) with a air pump would add oxygen to the tank, correct? My reactor is inline with my filter, what are the concerns of too much oxygen causing air lock? Supposedly, my rena has anti-airlock technology. I could go as far as to plug the air pump into my timer, but would it matter if it was injected during the day? The idea is the have both CO2 and O2 being injected into the water.

I should add that only 2 of 5 fish are hovering and they are doing it during the mid-day when plants should be producing oxygen. Any thoughts? Am I diagnosing this right?

EDIT: Ok, first of all this doesnt work, its too much oxygen for the filter. I tried it and my filter immediately started running dry. Second, I think it may be constipation, not O2. I'm going to run up and get some peas to help them.

[7Enigma]

Yeah, midday should be the time where you have the MOST dissolved oxygen in the tank (right before lights on in the morning is when you would have the least). If the fish are hovering midday then it doesn't sound like an oxygen problem. I take the peas (frozen), put them in a small glass cup of water, and microwave until boiling. I let them sit for a minute or so and then drain off the water, let them cool until you can handle them without burning your fingers, and I pop them into the tank water. The shell should stay in your hands, and the "meat" of the pea should shoot into the water. If they are surfacing due to constipation, this should help to clear up the blockage.

What do you feed them?

[Alshain]

I fed them bloodworms the day it started happening, normally I feed them flake food. See my thread in the sick fish forum for more information on what I have done so far. 1 of them is healthy this morning, swimming around nicely. The other won't go down to eat the peas.

[7Enigma]

For future reference I soak all of my freeze-fried food in a dixie cup of tank water for 30sec or so swirling it around. This hydrates the food (expands), and helps prevent constipation. One of the main causes is the fish eating the food as soon as it hits the water, and then expands in their stomach/digestive system. I haven't had a problem since starting this method.