I come across a lot of ponds THAT DO NOT have skimmer(s) and only a bottom drain. Without a skimmer one of many factors come into play....One; if any DOC's (dissolved organic compounds) in system they will remain on surface and start to build up! The other thing is any leaves, air borne debris will also remain on surface. Thus breaking down and creating MORE DOC's. Also mosquito's can start to breed as the water surface is not moving and they like calm dead water! Not to mention any Koi food that Koi have not consumed. We will talk about "calm dead water" at a later time...............I would like to share a story from one of our customers that thought they didn't need a skimmer....... Moral of story: Put a skimmer in system whether you think you need or not!
This story can also be found at our Koi club's website:
The Black Hole
Leland Helzer - July 2010
"Now you have a pond" my pond man, Mark Lawson of "Koi Depot", said when his work was done.
Our 4,000 gallon pond is a little over two years old now. When Thomas and I built it, we hired Mark to install a "Nexus 300" filter, and do the plumbing. He installed two 55 gallon pre-filters on the system with blue "Matala" mats as filter media. He asked me as we were doing the planning if I wanted a skimmer. I looked all around, the only trees in sight were palms. Since there were no trees with leaves, I could not imagine why I would need a skimmer. I said no.
Fast forward a year and a half. I had the most beautiful carpet of green algae that you can imagine and our seventeen koi grew and thrived. The Nexus filter was doing a great job as bio-filter, and all of our chemistry tests were perfect. The water in the pond was crystal clear despite the frequent job of cleaning the algae that kept clogging the "Matala" mats in the pre-filters. The bio-media that came with the Nexus never even got dirty, that was a good thing.
Eventually I said "enough is enough" to the algae problem. Around December of last year, off to the "koi store" we went to buy some kind of fish-safe chemical to get rid of algae. Hesitantly, I added the chemical to the pond. I hated using any kind of chemicals, hated it! I waited to see what would happen. After a few days, I had a small amount of dead algae floating on the surface of the water. Expected.
I cannot tell you how I looked forward to not having so much of the green algae clogging my pre-filters, and not having to work so hard to keep them clean. The next thing I knew, we had a problem that we had not had before, mosquitos and gnats! It seemed to me that the dead algae floating on the water surface provided the perfect breeding ground for insect larvae. For what ever reason, suddenly we had swarms of iinsects filling the air above our pond, and it was winter!
I found myself at the pond daily with a fine nylon aquarium net, skimming what seemed like thousands of insect larvae off the surface of the pond. The larvae and swarming insects were more insidious than algae had ever been! I was afraid my neighbors would soon be turning me over to vector control! Even though water itself was crystal clear, something had to be done about the bugs floating on the surface. I was quickly getting very tired of being "the skimmer"!
Finally I called Mark and asked him if it was too late to put a skimmer on our pond. "No" he said, "It isn't." He came over and determined that we could tie in to the existing pump and system. No more electricity would be needed. An additional 55 gallon drum with horizontal disc fiber filters would work to trap the skimmed debris and bugs inside the covered barrel, where they will die before they can reproduce. YEA!
Mark and his assistant, Pat, completed the installation. When they were done I stood there with total glee, almost obsessed, as I watched all the tiny insect eggs, and larvae by the thousands, being ever so slowly but steadily sucked into the "BLACK HOLE" that is our new skimmer. I was compelled to imagine a "Star Trek" episode with the "The USS Enterprise" about to be sucked into a "BLACK HOLE".
Not only does the skimmer help alleviate the insect problem, it also skims off excess proteins from the surface and oxygenates the water. All of these factors contribute to a healthier environment for our koi. The surface of the water is now as crystal clear as the water below. The flying insects have not yet been totally eliminated, but they are decreasing by the day. I hope to be completely rid of them with time. They have quite the life cycle. Each insect lives for months and lays hundreds of eggs.
If you don't have a skimmer on your pond, I strongly urge you to consider installing one. I am 200% pleased with ours!