from experience, several 300gph pumps in a room will shake the house down. a good idea is to use something under your tubs to absorb the vibration. if you can find very good packaging foam, the kind that is a few inches thick and stiff enough to support the weight of a full reservoir, that is the best. otherwise, you can use softer material such as old under carpet foam, folding it to your desired thickness. this will absorb the vibration caused by the pump, preventing your house from shaking. if you combine this technique with those super sleek pumps you have linked, i think they will make for a very stealth operation. good luck.