Unless you've added calcium in some other form, or done something suddenly raise the pH, it's not too likely you've got a calcium cloud.

Regarding the pump, if you get the model and make of the pump, you can *probably* get an 1HP or 3/4HP impeller & diffuser set + a seal, and lower the output. You'll have to open the pump and do some work on the 'guts' but on most pumps it's not hard if you're handy. You'll probably want to buy new seals and gaskets, so whatever you take apart, you can put back with new rubber.

Anyhow, you can always (as far as I know) run an electric motor at a lower than rated load.

If you like, you can try these people:
Lonnie 888-841-5050 x714
ljunghans AT a1poolparts DOT com
http://www.a1poolparts.com/
I'm not endorsing them, but I'm going to be ordering some stuff from them today. They seem to have good prices (better than my local wholesaler!), and a lot of parts in stock. I spoke to Lonnie yesterday, and she said she's willing to field calls from homeowners looking for parts. DO look at the diagrams, though. If you're not sure, maybe she can help you find it. Do so, study it, and THEN order parts. Trying to sell parts to homeowners who don't know what they are buying, or what they want is a real PITA.

-- not finished but gotta go chase some alligators that have gotten loose . . .