Just found this news group today and have read through all posts. Seems like a lot of great ideas and help abound in this space. Hope I am not butting into private conversations. Let me know if "butt out" is appropriate. I'm Ray and with my wife Kath and children built a pond last year. My guess is that it is about 2500 gals. It has a large rock border that rests on a shelf about 2 inches under water and a plant shelf about 12 inches under water. We wanted the bottom to be a haven for insect life and fish eggs and whatever else could bring ecolological balance to the pond so I've lined the bottom with river rock taken out of the ground when digging the hole. I have a two foot high waterfall that splashes down two levels (my attempt at aeration) and contains a biological filter that I have been carfeul to "feed" (with MicrobeLift products) and not disturb. I have started some lilies but have a fairly good growth of water hyacinth and I think something called parrot fern. I don't have a personal album online but could post a pic or two if someone would like to suggest the easiest place to access. I feel like I'm in an AA meeting when I confess that I couldn't wait to get fish into the pond and had purchased several very small (1") goldfish and some small (3") goldfish the second or third week after we'd filled it. They survived the winter easily (we're located in Rancho Cordova,California) and are still doing fine though now they're more like 5"- 7". Didn't know much (still don't really) about the care and feeding of ponds and fish so fed them all winter. Sometime in spring a friend of my son moved and gave us 6 10"-12" koi to care for, so I likely have too many fish for the pond size I have water striders, dragonflies and damsel flies in both final and larvae forms. The birds seem to like the free bathing as I have put in some small beach access spots. Apart from bouts with string algae and green water, the pond seems to be doing ok. My biggest bother is that with our 100+ temperatures, the water goes "green" and the bottom disappears. I see the fish at feeding time and an occasional orange shadow beneath the surface at other times but I'd like to see more of them. I have taken to treating the water with MicrobeLift/SA but it's rather expensive and while it seems to block enough light to inhibit string algae, it doesn't seem to have any effect on the green water syndrone. I can tell from my skimmer filters that I am getting a lot of the floating algae filtered out but obviously not enough to clear the water. All submerged rocks are covered with this algae.A local pond store suggests a UV light system. Has anyone experience with these kinds of systems? They're a little dear but if they work against the green water I would consider it. I was also wondering if anyone knew the range of temperaturees that I should try to keep the pond within. The water feels warm to my hand and I just feel that can't be beneficial to the fish. We've been shading the water with umbrellas because we're a new housing development and trees are not big enough to do so yet. Would it be OK to cool the water down somehow? Thanks in advance for any replies and advice.