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[APD] Re: RFUG vs UG

Date: Fri, 3 Dec 2004 08:03:55 -0600
From: "Tom Wood" <tomwood2 at flash_net>
Subject: [APD] RUGF versus UGF

>>T. Barr said: "I've had RFUG's for 10 years with plants."

>Why a RUGF versus a UGF?

>Just curious since I recently installed a version of a UGF in my 
>90 - Perforated PVC pipes under a sheet of plastic insect screen 
>under the substrate, piped back to a submersible pump that is 
>pulling the water down through the substrate. I could reverse 
>that flow to push water up through the substrate, but why?


I used 1/2" CPVC, it's smaller than PVC. I made a grid, like a giant spray bar and drilled holes in it. If I ran the water in normal UG fashion, the sand/detritus etc will be pulled into these small holes and also clog the avbove layers, causing pockets of high flow, inconsistent distribution etc.

By using Reverse flow, this eliminates these issues and I can use any size sand and have fairly consistent flow at higher flow rates, the water is prefiltered before being moved into the grid.

Keeps the substrate fairly clean over long peroids.
No need for plastic insect screen also and allows more space for roots(all the way to the very bottom of the gravel and around the pipes).
Depending on the spacing, you get a pocket of high Redox and low redox levels since some parts of the substrate are not being provided with flow(unlike the Plate designs) much like an egg crate shape where the outflow leaves the RFUG.

They are also the easiest UG's to make and cost about 10$ for almost any sized tank and if you want to add heated water into the substrate, these make more since. This is done mainly for efficient heating of the tank, not the cable business.

Tom Barr  



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