Pond Algae & Biological Filtration

by DFS-Pet-Blog on October 4, 2010

**Guest post from Heath S.**

Last month we added an additional 20,000-gallon pond to our existing ponds. The existing ponds consisted of approximately 8,000 gallons with the main pond pumping into a smaller “catch” pond and then out the waterfall back into the main pond.
A couple years ago, I was messing with the inbound water flow direction into the upper pond; with two filtration pieces opposite each other on the upper pond, I began to notice a collection of waste in the center of the pond. As the season had progressed, I kept an eye on the upper pond. I noticed much less debris or waste buildup in the main pond.

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The next summer I again had the same setup with water flow. Midway through the summer, I would have to vacuum out the upper pond. That was it for maintenance. The pond vacuum made that chore very simple and quick.

New pond addition.

New pond addition.

As we began to finalize the new pond addition, we used the filter from one side of the upper pond on the new pond. Within a couple days, the water began to seem full of particle matter and then “pea soup.” I’m sure there had to be enough buildup in the upper pond to cause some water blurring but not the algae bloom.

All of the proper steps had been taken to de-chlorinate the new pond as well as letting the water age for a week. One very important step was overlooked and that was to establish proper biological filtration. The large increase in water volume did not contain sufficient amounts of beneficial nitrifying bacteria. This wouldn’t normally be that big of a deal but I do have a large fish load. Most of the Koi fish are over 20 inches and have appetites that match their size. With the size of the prior pond being a little small for my fish load, I made it up in extra water flow and filtration. The bacteria population was well established and large enough to keep up. With the additional 20,000 gallons of water, everything was out of balance. All three of the ponds succumbed to the algae bloom.

I have never been a fan of using algae control treatments, but in this case, I knew it was needed. I treated the pond with AlgaeFix and installed a temporary 35-gallon garbage can filter to collect the algae die off.  Within two days, the pond was crystal clear again.

I have to say I was very impressed with how quickly the AlgaeFix worked and how little it affected the Koi and other pond plants. As silly as the garbage can filter sounds, it quickly cleared the dead algae and helped polish the water back to its crystal clear state and is in my garage for hopefully no future use.

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