Okay, I just purchased a 55 gallon fishtank on craigslist, just cleaned it up as good as a could, had a butt ton of calcium build up on it. Well the question I have is this, I have 2 29 gallon fishtanks both have under gravel filters, would it help or make any sense at all to put one of those under gravel filters into the 55 gallon even though it would not go the length of the tank?