WHICH AIR PUMPS DO YOU GUYS USE?

[HTH]

Are there any small air pumps (kits) that allow for adjustable output? If I go with 2 stones during summer time, one in shallower part and another in the deep end, I would like to turn off the deep end in the winter to preserve the thermal mass)

With airpumps we bleed off (waste) the extra air. With water pumps it is generally ok to restrict the output. Doing this with a diaphragm based air pump would be hard on the diaphragms.

 

[mario]

I ended up buying the AQUASCAPE POND AIR 2.
First impressions are that the pump is quiet but not silent.
The air hose is not weighted, meaning that it floats unless placed under a rock. My pond is 5' deep in one spot so diving in to place a rock over the air line is not going to be fun.
Second is that the stone is very light and not weighted towards the bottom. I had to drop it 5 or 6 times before it landed right side up.

I'm not saying that I regret the purchase, just that I noticed some issues that I was not aware of.