while trying to recreate stealth hydro's system, i kept running into a restriction problems from the manifold i got from the hardware store (1/8 ports) so i made my own out of a 2" cap, 2" to 1/2" reducer and 6 1/4" port. while putting it together i noticed that i had room for one of those small round air stones, so after taping a hole for the air stone and air line. after letting it dry (although the ports comes with threads i screwed up the holes and had to glue them) i hooked my new manifold to the 265 gph pond pump and the air line from the manifold to one side of the duel port air pump and the other side to the air stone for the res and filled up the tub check it out. the air stone in the manifold was doing a good job of making bubbles in the 1/4" tubing but the res air stone sucked, (will get another air pump for the res) hooked both sides of the air pump to the manifold and was amazed at how much bubbles was running through the 1/4" tubing. the water comes out all fizzies and the water is soft fluffy almost.