Here is a great article that I found on another forum site
After many failed attempts at growing plants in sand, I had eventually succeeded with a few species in a tank that had a good year's accumulation of mulm stirred into the substrate. I had a very good light on the tank - a Catalina 4 bulb T5 high-output fixture with individual reflectors - and eventually concluded that substrate nutrients were the limiting factor. After I moved and was able to bring at least some of each plant species I had (described here), I decided to try to fix the underlying problem. Every fish I've had has seemed happier in a tank with plants, and the plants are fun to grow too. Erica suggested kitty litter as a substrate (on page 25 of that thread). I had initially intended to lay down a layer of topsoil and cover it over with litter, but after reading a chemical analysis she posted of the stuff I was convinced that the soil was unnecessary.
I used WalMart brand Special Kitty litter, it being the only one I was sure didn't contain leachable chemical additives. Labels on any of the available brands were not helpful in determining their contents, but all of them made some sort of claim like "odor neutralizer" or something that suggested an additive.
The tank was set up somewhat hastily because the air pump that was powering the sponge filter in the moving bucket had failed two days before the tank was delivered and I was in a hurry both to address aggression due to overcrowding and underfeeding and to alleviate the rapidly deteriorating water conditions. The bucket was overstocked to the point that twice daily 90% water changes were not keeping it from smelling bad (though they did seem to stress the fish). I ended up just dumping in a 25 pound bag of kitty litter and pouring water on top of it unrinsed. This is definitely not the recommended procedure, but due to the chaos of moving I didn't have a second bucket to rinse with. In retrospect it might have even been better to fill the tank with water, add the fish, and use that bucket to rinse the substrate. I didn't do that because I wasn't sure if the litter was fired or not, and thought it might soften in water and muddy up even if rinsed. It turns out the particles hold together pretty well and that probably would have been fine.
Pouring water over unrinsed litter resulted in extreme turbidity with only about an inch of visibility. I ended up not adding the fish for another 18 hours while I ran two large sponge filters with air pumps and an Aqueon 55 hang-on-back filter to try to clear the sediment. After two days the water was reasonably clear but I still thought a large water change would be needed to remove the remaining silt. At this point I removed one sponge filter, leaving the cycled one that had traveled with the fish, and rinsed out the other in tank water. Both produced a huge amount of silt when squeezed. The HOB filter pads were essentially clean. It does not appear to have made any significant contribution to the cleanup. Unfortunately I have no pictures of the tank during this period as it just wasn't a priority. At this time I added the plants that traveled with me.
By the third day the water was crystal clear and has remained that way. Moving plants still stirs up a small cloud of silt, but it settles quickly. After two weeks I replaced the air pump on the sponge filter with a 160 gph powerhead and removed the HOB filter because even with an excessively high water level it was causing too much downward current underneath it which was both stirring up the substrate and splashing the light fixture. One thing I noticed in the move was that the light's reflectors had developed hard water deposits that were probably diminishing its performance. After trying to clean these, and replacing the bulbs, I could see a marked improvement in the color and brightness of the light. The powerhead was significantly larger than I had intended, but was the smallest available at the pet store. The hardware store I checked had some smaller capacity pumps but they all had intake screens on both sides of the housing rather than a pipe, so they weren't suitable to power a sponge filter.
After many failed attempts at growing plants in sand, I had eventually succeeded with a few species in a tank that had a good year's accumulation of mulm stirred into the substrate. I had a very good light on the tank - a Catalina 4 bulb T5 high-output fixture with individual reflectors - and eventually concluded that substrate nutrients were the limiting factor. After I moved and was able to bring at least some of each plant species I had (described here), I decided to try to fix the underlying problem. Every fish I've had has seemed happier in a tank with plants, and the plants are fun to grow too. Erica suggested kitty litter as a substrate (on page 25 of that thread). I had initially intended to lay down a layer of topsoil and cover it over with litter, but after reading a chemical analysis she posted of the stuff I was convinced that the soil was unnecessary.
I used WalMart brand Special Kitty litter, it being the only one I was sure didn't contain leachable chemical additives. Labels on any of the available brands were not helpful in determining their contents, but all of them made some sort of claim like "odor neutralizer" or something that suggested an additive.
The tank was set up somewhat hastily because the air pump that was powering the sponge filter in the moving bucket had failed two days before the tank was delivered and I was in a hurry both to address aggression due to overcrowding and underfeeding and to alleviate the rapidly deteriorating water conditions. The bucket was overstocked to the point that twice daily 90% water changes were not keeping it from smelling bad (though they did seem to stress the fish). I ended up just dumping in a 25 pound bag of kitty litter and pouring water on top of it unrinsed. This is definitely not the recommended procedure, but due to the chaos of moving I didn't have a second bucket to rinse with. In retrospect it might have even been better to fill the tank with water, add the fish, and use that bucket to rinse the substrate. I didn't do that because I wasn't sure if the litter was fired or not, and thought it might soften in water and muddy up even if rinsed. It turns out the particles hold together pretty well and that probably would have been fine.
Pouring water over unrinsed litter resulted in extreme turbidity with only about an inch of visibility. I ended up not adding the fish for another 18 hours while I ran two large sponge filters with air pumps and an Aqueon 55 hang-on-back filter to try to clear the sediment. After two days the water was reasonably clear but I still thought a large water change would be needed to remove the remaining silt. At this point I removed one sponge filter, leaving the cycled one that had traveled with the fish, and rinsed out the other in tank water. Both produced a huge amount of silt when squeezed. The HOB filter pads were essentially clean. It does not appear to have made any significant contribution to the cleanup. Unfortunately I have no pictures of the tank during this period as it just wasn't a priority. At this time I added the plants that traveled with me.
By the third day the water was crystal clear and has remained that way. Moving plants still stirs up a small cloud of silt, but it settles quickly. After two weeks I replaced the air pump on the sponge filter with a 160 gph powerhead and removed the HOB filter because even with an excessively high water level it was causing too much downward current underneath it which was both stirring up the substrate and splashing the light fixture. One thing I noticed in the move was that the light's reflectors had developed hard water deposits that were probably diminishing its performance. After trying to clean these, and replacing the bulbs, I could see a marked improvement in the color and brightness of the light. The powerhead was significantly larger than I had intended, but was the smallest available at the pet store. The hardware store I checked had some smaller capacity pumps but they all had intake screens on both sides of the housing rather than a pipe, so they weren't suitable to power a sponge filter.
