Re: aqua babies?
Here is a quote from a nice web page(long)
Kinda for you ronrca, may not be exactly what you wanted.
"Q: There is a system that plants create oxygen that is used by fish and converted to CO2 which is again changed be the plants into more oxygen.
It is nice to think that the plants help the fish by providing oxygen and the fish help the plants by providing CO2 and fertilizer. In most aquariums, this is not true.
First of all, plants convert CO2 and nutrients into carbohydrates and oxygen provided there is enough energy (light) to maintain photosynthesis. As plants grow faster, they draw more CO2 and nitrogen and phosphorus from the water and they generate more O2. This is good for the fish. However, fish won't produce enough CO2 to raise the level above normal equilibrium levels (2-3 ppm) unless you are massively overcrowding the fish. It will diffuse into the air as fast as the fish produce it.
How do you tell how fast the plants are growing? Besides making physical measurements, you can monitor the O2 in the water with test kits. You will find that in a non-CO2 injected aquarium the O2 level is around 80-85% of saturation (O2 saturation is 8.1 mg/l at sea level and 75 F, lower at higher altitudes and temperatures). In a tank of water with no life and decent circulation, you will find that the water is very close to O2 saturation due to diffusion at the water surface. As you add fish and bacteria and other O2 users, you will find that surface diffusion is not enough to keep up with the O2 demand, and the O2 level drops to the 80-85% level. Even massive aeration (bubble wands, etc) is not enough to get the levels above 90%. Even trickle filters will not raise O2 above 95%, contrary to the ads you see. This is not conjecture, but based on measurements made in our home aquariums.
The only way to actually increase the O2 level of the water is to either inject O2 with an O2 reactor (which no one does) or to get some biological process going that can force addtional O2, which is where plants come in. Keep in mind that plants *only* generate O2 when they are photosynthesizing; at other times (like at night), they are O2 users along with everything else. I have found that without CO2 injection, the plants do not produce enough O2 to raise the O2 above what a tank without plants would have. The only purpose they serve is to provide decoration and hiding places for fish. They do not provide "balance" in the biological sense.
With CO2 injection (and proper light and nutrients, of course), you can phyically see the plants generating O2. Bubbles form under the leaves and streams of bubbles come from broken leaves and stems. We typically measure from 110 to 125% oxygen saturation (which is good for our fish, since we live at a high altitude and they would see a deficiency otherwise). When plants are growing this fast, they are also removing more pollutants from the water and provide some of the balance you are trying to achieve."
Found it intresting about the percentage of O2 in the water.
