"Airstones drive off CO2" only if the dissolved CO2 in the tank is greater than its equilibrium concentration in the air, which usually only happens when you're adding supplemental CO2 (or if you have a LOT of decaying organic matter on the bottom, or an extreme fish load). In a typical aquarium with low to normal fish-stocking density and abundant growing plants, the plants will consume all the CO2 produced by the fish and bacteria, and water movement (e.g.aeration) will INCREASE the CO2 available for the plants. The claim of "aeration is bad for plants" comes from the high-tech CO2-supplementation people, and is usually NOT TRUE for non-CO2-supplemented tanks. In natural streams there are groundwater seeps with higher-than-ambient dissolved CO2 (similar to high-tech planted tanks), and plants can take advantage of these very localized micro-habitat patches.

If keeping cool is an issue, an airstone will add less heat to the tank than a powerhead (water pump) will. Evaporative cooling (enhanced with a fan) can be significant, especially if your room humidity is low.

Airstones drive off CO2, which is what want for the fish, but it is also the CO2 plants need when the lights are on. As a general rule, as little aeration as possible when live plants are the goal, 'specially with extra light. Heck, the serious plant people ADD CO2 for their plants. Air is a good supplement for non-planted tanks and cheap way to add water movement, but it is NOT substitution for adequate filtration.

I will add the other airstone then. the only humidity we get is from the 300 gallon reef aquarium, 20 gallon native, 45 gallon native (will be 150 tomorrow), and the kitchen sink water evaporating. My mother does not want me to use evaporative cooling. Are redside dace schooling fish? I am going to get western blacknose dace and redside dace first, then I will get the redbelly dace later. I will most likely just get 3-5 each and remove the fathead minnows if there is too high of a bio-load.

I know this is off topic, but how large does a golden redhorse need to be to be with a brown bullhead catfish? The golden redhorse is ~2.5in and the bullhead is 6-7in now. The only way I could think this ties in with the dace topic is that the redhorse is in the 20 and I was going to put it with the bullhead when it gets big enough so there are less fish in the 20 gallon.

since the lid my dad is making that will have an opening for the filter, should I remove the lid at feeding time, or should I put the food in the water the filter returns?

Thank you.

Edited by Leo1234, 30 June 2014 - 11:09 AM.

The redhorse needs to be at least as wide (side-to-side) as the catfish's head. Nearly all minnows (including dace and shiners) are schooling fish, although some become territorial "loners" when breeding (especially male Cyprinella shiners). I would open the lid for feeding, so that not too much food gets sucked into the filter before the fish can eat it. Also you don't want to encourage the fish to go "looking" for more food by jumping through the filter chute opening. I prefer 2-piece lids, with a back piece (around the filter tubes and under the light) that stays on and a smaller front piece that I can lift off for feeding, netting fish, thinning plants, etc.

sorry for bringing up an old topic, but I just recently changed my 20 gallon into a planted stream aquarium. I read on an old topic that dace don't jump as often with a current. Is this true? I still want an open lid aquarium as long as the dace won't jump. Thanks.

It only takes one jump to die. I'd cover it or extend the tank walls to create a "fence"

so current does not help? are central stonerollers less likely to jump? I need a way to get rid of some algae in my 20 gallon and I read that stonerollers are good for getting rid of algae.

They seem to be more relaxed and comfortable in a tank with current, but they may still jump out. That's just the nature of minnows that live in shallow rocky streams, especially in small headwater creeks. Their instinct to swim & jump up rapids is what allows them to colonize and persist in headwater creeks.