Gander, Am I correct in that you live in OK.
If so, do you ever get cold enough that it kills off the Azolla... ie. your picture P1010005aaa.jpg.
It just showed up here two years ago. I think a bird must have left it as a gift since I thoroughly clean evrything before planting. I too thought it was cool looking until it began devouring pond surfaces like the "Blob" from the old movie. My only recourse is to continually wash it all out. I had finally rid myself of it by March of this year. Suddenly about a month ago, it returned like a horrid sequel. The frogs, birds and dragonflies are only too happy to help propagate this monster. Up north it dies and they have to pay by the cupful to get more yet I had a really tough time killing it.
Tim