Saltcorner
By Bob Goemans
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Bob Goemans corresponds with Rico Horton

Rico Horton writes...

Hi Bob,

Love your FAMA articles.

My problem is I just purchased a 50 gallon pentagon aquarium and I want to set up a plenum NNR filter in the tank and would like any suggestions on how to build a plenum for this pie-shaped aquarium? Or should I build it in a separate sump? The problem with this idea is there is not much space under the tank for a big enough sump to do a good job of keeping nitrates down in a mixed reef tank of fish and corals. Can a person put an inch of extra coarse crushed coral or aragonite sand and just put the screening on top that, then top that off with the finer aragonite (2inches) and screening then another 2inches to get the proper depth and accomplish the same process of the plenum? I want to get this right the first time!

Thanks,

Rico Horton

Bob replies...

Hi Rico,

Pentagon shaped!

Let me first address your thought on an extra inch of sand idea. That's not an acceptable approach. The plenum space 'must' be on the bottom. That space consists of the screened grid. On top of that comes four inches of substrate.

It sounds like you have never read my Live Sand Secrets booklet. If not, checkout my new website at www.saltcorner.com. Go to my 'Bob's Books' section and check them out. Also, read the pages in the Controversy section.

With a pentagon shaped aquarium I would honestly recommend a shallow substrate consisting of about 1.5 inch in depth, and consisting of about 2 mm size sand grains. Leave as much sandbed surface open for vacuuming, and the system should do well. Maybe not as good as with a plenum, but you don't seem to have the space for one. Keep in mind that any type system, plenum, Berlin, DSB can work if the right husbandry procedures are followed and mated to the right bioload.

Hope this helps and keep me posted,

Bob

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