Hi Bill welcome to AZ!
Are you in the Valley? If so, the warm weather here may explain the
froth...I am in Mesa and our koi have been frothing up the water with
romance for the last few weeks as the temperatures climb. (For those
of you not in the Phoenix metro area, we're expecting our first 100
degree temperatures any day now...*sigh*) My koi generally decide
it's too hot for mating around the beginning of June, so if that's
what's happening, it should be only temporary.
As for the rest, we have a great pond store out here in east Mesa and
I know some great resources for pond plants if you want to drop me an
email. Plants do make all the difference!