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Pond Edge - bog / plant filter

15 years ago

My pond is about 5' x 10', sort of kidney-shaped, with an average depth of 3'. By the time I wrestled with what to do for a stream (almost 2 years now!), I ended up with one 20' long. The pond seems small now, by comparison, so I've toyed with using the uncut excess liner to make a bog / plant filter extension on one end. I'd like opinions on what anyone sees as pros or cons to my plan.

Another consideration in this, is that in the original excavation, I marked the perimeter with a 1 foot "shelf", just a couple of inches below grass level. I don't want the "rock necklace" look, however, so I flooded and inch of water onto this shelf, making the pond look a lot bigger, then toyed with ideas of how to finish it. In the meantime, it has provided a great ledge for frogs to hide on, underneath the rolled up liner.

Anyway, this is my plan:

You can see the original perimeter shelf at the top. I dug the bog to the right of that. With the original shelf in place though, this leaves a liner eyesore, just under the water. My plan is to cut about 5" off the height of this shelf, leaving it about 6" under water. Then I'll fill the bog with pea gravel, sloping from water level at the right, and meeting up with the new shelf level, 6" under water, at the left. I figure that this will give me lots of flexibility with planting depths for marginals - from 0 to 6". This will also give frogs a convenient ramp to get out of the water, regardless of fluctuations in the pond's water level. Supply water will slowly percolate up through the pea gravel, over the underwater shelf, and into the pond.

I thought that using some kind of fine particle substance in the bog (special soil?) might form a better filter, but I seem to be seeing a concensus that it's best not to introduce anything with nutrients, but rather, force the bareroot plant anchored in the gravel, to pull nutrients from the water, to keep algae in check by competing for its food.

That's about it; I look forward to anyone's feedback.



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