well, please do a little research on the care and requirements before you buy 10 clams. the reason why people say not too many is because they have a high demand for calcium and alkalinity, which can be quickly depleted in a tank of that size. the 24 gallon with 12 in there is probably manually dosing 2 part solution on a daily basis, or is running a mini calcium reactor of some sort to help keep critical parameters steady. otherwise it is just a bad idea.