yes, using a bak pak skimmer. the crab was pulled out of the tank as soon as i saw him so it wasn't in for more than a few hours. i put about 1 gal of tap water in for a top off a while back but that's it. i usually get my water for changes from aquariumD. i had about 2-3 days with poor flow in the tank (power head took a dump) but that's been replaced since. i think i've got sufficient flow.