Here is a cheap way to aireate. Take a washing machine feed hose (about 1/2" id). Remove the coverplate and eyeball on one of the return jets from the pump and dry the cover plate. Use a copious amount duct tape to tape the hose so that end will be near the center of the eyeball and extend into the jet of water about 1-2" - you may need to form the hose slightly with some hot water so it points in the direction of the water flow. Don't tape around the back of the plate or you won't be able to put it back on. Put the coverplate and eyeball back in and lay the hose on the deck or rail of the pool. When you turn on the pump play with hose until you get the maximum amount of air coming out. You just made an eductor. You'll hear the air being sucked in and see a large stream of very fine bubbles. With this I could drive my alkalinity down in hours. Looks hokey, but heh - free and take it out when your done. And NO, I'm not red-green.