Thanks ksteem! Right now we don't use any special equipment to keep it clean. We use it like a manual aquaponics system to water the garden and vegetables with and back fill from a fresh water stream behind it. I looked at a filter and pump system but because of the size of the it would have to be imported unless I could make one myself. I've seen some great DIY shower Filters made from stacked plastic boxes with filter foam at the top and lava rock in the others. The water pumps in the top and filters down through the layers and out the bottom. The algae would still be a problem though if there are too many nutrients in the water. You could try adding lots of water plants to out compete the algae. It's a lot of trial and error.