eric borneman was just at our club meeting on sunday doing his oxygen seminar. On a tank that size, the airstones arent going to do much in way of making sure your water is oxygenated. At least, you'd need lots of airstones, then you'd have to worry about excessive salt creep. Your better off trying to get your pump running, or better yet get some kind of light over your tank. Lights are the number 1 factor in getting the water re-oxygenated due to photosynthesis he says.