Hi We've got a bathtub in the back garden converted to use as a fishpond. Currently it has only four small goldfish in it. We've had the setup for more than a year now. It has some water plants in there, transplanted from a nearby river. That'd be about 50 gal of water there. What's brought me here was a search for some way to cut down on the green in the water - the algal growth. Found the algae scrubber article. It looks to me like what I need. If I can get the water clear, and yet remain healthy, then I can landscape the bottom of the thing and make it altogether a better exhibit. This 'living reef' idea of yours is great. Landscape the bottom - and sides - like a reef is a great idea. But I'd need to be able to see.... Currently we're running a 200 gal/hr pump feeding a plastic wool filter and I'm having serious doubts about that. It doesn't cut down the algae, totally ineffective. It is merely a mechanical filter and i don't see we need that much mechanical filtration. We did it only because of the widespread info that water should be filtered at a rate of about 4 x tank volume per hour. This is the only forum I've ever found that knows about algae scrubbers. I think there may be more real expertise here than anywhere. Any advice on maintaining and improving our pond would be appreciated. And advice on an algae scrubber for our setup - the point being that perhaps we don't need lights? The fierce sun hereabouts is what's promoting the growth of algae within the pool, seems to me I should be able to make a scrubber that utilizes that same sun, right? My current filter that I'm having doubts about, is enclosed - hence it's dark in there. Black sludge grows in there. I imagine it's doing no good as an algae scrubber. As I say, it's just working as excessive mechanical filtration I think. For a while there the filter setup was resting on a flat steel plate laying on top of the pond. The spillage, constant overflow from the filter began to get seriously thick and green. It was exposed to the sun you see. Look to me like I had an algae scrubber operating there and then, what do you think? Well that introduces us and our setup and concerns. Perhaps I should now open a thread to ask the above questions? This might not be the right place for them?