Want to keep local cold saltwater specimens. These I will collect myself. Have a tank 1260mm long by 400mm deep by 520mm high. Want to keep among other things,bivalves such as Dosinia anus to study their interaction with paddle crabs, but have been told sand presents problems and a coarse material would be better in the bottom of the tank. Have been getting conflicting advise on filtration?? Also air temperature. My house faces North and is very warm. Have tried without success to purchase a book covering all this so would be grateful for some guidance. Thanks.