Why do you need to buy Earthworm casings when snails are available?

I don't see anything magical in earthworm castings, but they do have a lot of soil minerals, clay silt, etc. in them whereas snail droppings are organic---undigested algae scrapings, etc. Basically, earthworm castings add soil to the substrate, and snail droppings add organic matter, basically mulm.

HeyPK, what is the difference--is it what they eat or how they eat? (I don't really know anything about earthworms).

Earthworm castings are earthworm excrement. Earthworms filter soil through their bodies and excrete it out in a more potent form since it contains nutrients that are in a more concentrated form within the castings, and also it contains lots of bacteria that help process the castings into a more readily used form for plants. Not only that, but earthworm castings are very porous making them ideal for growing plants.

Thanks Raul, so soil moves through them as opposed to snails who eat whatever they find and simply excrete similar to fish.

where would I be able to get some earthworm castings? is there a limit on how much I can put in a tank?

I'm not sure, Turtlehead -- I wish I could answer that. Perhaps someone will come by and be able to answer that one!

Well, I am sure you can order them off the net, heck, you can get anything from the net If you have time, depending on your climate, you can collect them in the "wild" a day or so after a good rain, look around in places where the dirt is kind of hard and dry. You should be able to find lots of small mounds, about1/2" high or so with a hole in the middle. Collect the little mounds and you're off. I belive the castings have to be soaked and boiled or something...not sure though. I belive there is an article in the archives (substrate) from th eearly beginnings of APC. Also, I think there is an article on www.eaquaria.com

u can get a small earthworms box in a fishing store and grow them your own in a box of peat. thats what i do