We recently received a question on a previous blog: BOG FILTRATION, THE PERFECT COMPLEMENT TO BIOLOGICAL FILTERS. The question was:

Do you have any additional information near building and calculating an upflow bog with EcoBlox, similar shown in the graphic at the end of this weblog post? You already talked a bit almost the surface surface area of the bog compared to the pond but what near the depth and the number of blocks stacked on each other for example?
I want to build a 15′ x thirteen′ pond with 3000 gallons and 9′ stream. Pond volition be filled with stones and gravel, some plants and 20 goldfish (around 8″). How many blocks do I need and how do I arrange them for a fitting area of the filter? Practise you have any recommended product to be used every bit tube nether the blocks? Or practise I have to build 1 myself? If and then, do yous have any instructions to do this?

Bang-up question O Noble Ponderer!

Bogs are sized by surface area. 10% of the area of the pond in bog area is sufficient to consume all the nitrates a goldfish pond is probable to produce. At the other stop of the scale are Koi, which need 3 times equally much area, thirty%, planted to bogs.

With 205 square anxiety of swimming, twenty square feet of planted gravel volition be sufficient. You have a nine' stream, which simplifies matters greatly. What I would do is fix i or ii Eco-Blox at the top of the stream, on the existing grade on top of the stream liner. I would install two ii" or 3" flanges or bulkhead fittings on either side of the chamber thus created, downwardly low so h2o enters and exits the Eco-Blox almost the bottom of the block. On one side I'd attach the piping from the pump, on the other a drain valve. Take a expect at the sketch.

Water comes from the skimmer into the Eco-Blox on one side, flows upwardly and out through a 4-6" layer of ¾-1" gravel on top planted to various low grasses or other aquatic plants, which are also planted in the gravel of the stream. The Eco-Blox under the gravel acts as a settling chamber. The outlet on the side opposite the inlet is valved. The valve is buried well-nigh the flange or bulkhead fitting, attached to a piece of pipe out to daylight somewhere.

I usually but set an 18" length of four" piping vertically over the valve and so the handle tin can be accessed periodically to bleed out the muck which will accumulate in the chamber. If I can't reach the valve with my hand, I'll slot the cease of a pipe to create a wrench to plough the handle. This is necessary usually only in one case or twice a year.

You'll have a great little active bog filter that uses the top of Eco-Blox bedchamber plus the stream to provide the necessary area for plantings. Plus a built-in settling chamber that will remove much of the suspended organic debris constantly and automatically. You may also consider adding a lesser bleed to the skimmer, to pick up the remainder of the debris. But that's the subject of another post.