# DIY bog filter for outdoor pool



## TheOldSalt

Have you ever noticed that in ponds with lots of crud on the bottom or choked with plants, the water is often crystal clear?
After seeing how clear the water in my goldfish pool was, and how fantastic the fish looked, when the pool was so full of Anacharis that the fish could hardly swim, I decided to set up an outside bog/plant filter.

I built a little 4X4 wooden frame next to the main pool, and on top of this I put a hard plastic round kiddie pool. This arrangement puts the little pool about a foot higher than the top of the main one. I put some dirt on the bottom and stuffed it with plants. I drilled a hole near the top rim, and mounted a standard bulkhead fitting through the hole. To that I attached a piece of ( 1&3/4 inch? ) PVC pipe which drained back into the main pool. 

Now a little Pondmaster pump in a little strainer box sends water from the main pool into the bog pool, and the water returns via gravity to the main pool. The THICK mass of plants gobbles up nutrients and polishes the water, and now the main pool is very clear, algae free, and full of happy fish with plenty of swimming room.
There is no mechanical filter in use, and apparently I don't need one; everything is looking fine indeed. I'm going to build similar bogs for the other pools.


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## redpaulhus

What are you using for bog plants ?
Any pics ?


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## TheOldSalt

No pics yet.
The term "bog" is a bit misleading, as most of my plants are floaters which only barely touch the bottom of the pool. Myriophyllum and Elodea constitute the bulk of the plant mass, with Hyacinth and Frogbit on the surface. The thing to bear in mind is that the plants are entangled in a thick matrix with little open space in the pool remaining. Fish would have a very hard time trying to swim through it.
A side benefit is that the plants are thickly coated with aufwuchs, so feeding fry is easy.


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## John

Very interesting! I really enjoy hearing about other people's ideas for filters!


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## aquatic_dynasty

So no more usage of UV-Lights? Water never gets green? WOW! Very good idea...I might want to steal it. :-D


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## TheOldSalt

It really works! Feel free to steal it all you want and enjoy.

Adding a mechanical/biological pond filter would polish out all the particulates and make things even better, I suppose.


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