No chlorine, I'm on a well. I drove all over town and no luck on a small continous duty type compressor. But I think I bought myself some time. First good news - it clouded over and a strong south wind came up. That pushed all of the dying duckweed to one end. I bought hardware to split my air line and add a second defuser to my pump. This should cut some of the back pressure and put more air volume into the water. With that thought, I pulled in the air line and found that the one diffuser had split (this is the EPDM type). So for now, I replaced the diffuser with my spare and set the line back out. The air stream looks much better.

I don't think I'm out of the woods bacause the weed is in the dieing phase and hasn't started decomposition - the point where bacteria uses O2.

Bruce, yes. If it gets hot and calm again, I may hook up the sweeper nozzle. This will cool the pond and add aerated water to the surface anyway. I'm going to get on the phone / net tomorrow morning and buy a second pump. Doesn't hurt to have a second / spare...

Thanks guys.