Hey, gunner. I've been using home-grown loofa (lufa, loofah, many variations in spelling) as a static immersion filter for almost two years now in my 1000 gal koi tank. It works quite well, and each sponge lasts 6 months or so. Lufa is just the internal structure of a squash that is harvested young to eat, and mature to make lufa sponges. I dont use any chemicals to bleach it, just let it mature, pick it before it starts to degrade, and dry in the sun. When dry, just crumble the skin off, shake the seeds out and it's ready to go into the pond. It's a prodigious multiplier, and three vines made dozens of sponges. Glad to see someone else thought of it.