I was thinking about putting shell dwellers in my 55 gallon however doing this would limit my load I can have in my 25 gallon tall aquarium. I was just curious if the 25 gallon aquarium is to tall to have shell dwellers in, I'm thinking it should be about the same height as the 55 gallon. I'm setting up my 55 gallon tomorrow with pool filter sand and once the water quality is perfect will be adding my fish, I will then need to syphon out the gravel from the 25 gallon and then apply pool filter sand to replace the gravel. Any suggestions on the best and easiest way to remove gravel and put sand in it's place.