hey,
i kept a cold water marine it was in a 2.5ft tank which i thought was way to small i collected shrimp, small fish, shell fish all sorts but i didnt get much sea weed as i didnt want the tank to go all yuk i couldnt aford a cooler so what i done was freezed bottles of salt water and put that in the tank and that kept it cool i just feed them on flake, brine shrimp, frozen blood worms pritty much any thing tropical fish eat for filteration i only use a internal shark av which kept it pritty clean but i didnt fortnightly water changes i have to air stones running in it and a moon tube light it was so interesting to watch i will definitly get another but in a bigger tank
my friend tim downs(newtman) also set one up at the same time and he still has his going
cheers
anthony