Water return into plenum space

[jdrmd]

I bought a 135 gal tank recently and all the plumbing was already setup. The bottom has eggcrate wrapped in screen covering the bottom. The eggcrate is elevated above the bottom about 1 cm by plastic and pvc(the guy did a really nice job setting it up). The water return is directed below the screen wrapped eggcrate in two places adjacent to the internal overflows. The tank was used as a fish only tank before. I am setting up a reef tank with live sand and rock. What is the current opinion on this kind of setup. It is kind of like a plenum but has the water returning to the plenum space. I would really appreciate some thoughts on this kind of a setup.
thanks
john

 

[Rod Buehler]

I bought a 135 gal tank recently and all the plumbing was already setup. The bottom has eggcrate wrapped in screen covering the bottom. The eggcrate is elevated above the bottom about 1 cm by plastic and pvc(the guy did a really nice job setting it up). The water return is directed below the screen wrapped eggcrate in two places adjacent to the internal overflows. The tank was used as a fish only tank before. I am setting up a reef tank with live sand and rock. What is the current opinion on this kind of setup. It is kind of like a plenum but has the water returning to the plenum space. I would really appreciate some thoughts on this kind of a setup.
thanks
john

The idea behind a plenum or a deep sand bed is to provide anaerobic areas to harbor anaerobic bacterias (low oxygen). pumping oxygen rich water through a plenum/sand bed would render it useless as a "denitrafacation filter"

 

[jdrmd]

The idea behind a plenum or a deep sand bed is to provide anaerobic areas to harbor anaerobic bacterias (low oxygen). pumping oxygen rich water through a plenum/sand bed would render it useless as a "denitrafacation filter"

Thanks, I understand the concept of a plenum. I was wondering if anyone had seen a setup like I described and if so how successful it was.
Thanks
John

 

[Chichas01]

I could be wrong, but I think the intent here may be to keep detritus from ever settling into the sand bed by having the water flow upwards through the substrate. Seems like I've read some articles in the past describing this.

 

[Rod Buehler]

never mind, I mis-read .. Are you, or was this eggcreate/screen covered with sand AKA plenum style?

 

[Rod Buehler]

if so..

Thanks, I understand the concept of a plenum. I was wondering if anyone had seen a setup like I described and if so how successful it was.
Thanks
John

I guess I need to know of "successful" of what (?), then.

The main purpose of a plenum is to de-nitrify.

The only way to de-nitrify is with anarobic bacteria.

The only way to get anaerobic bacteria is to have low/no oxygen areas.

Pumping water under the plenum is providing oxygen therefore limiting the anaerobic bacteria therefore limiting the de-nitrying to a minimum.

Pumping water through a plenum would essentially be turning your plenum into a reverse flow undergravel filter.

Can they be succesful at helping maintain aquaria? you betcha

Can they be sucessful at denitrifacation? doubtful (very)

 

[seahawkone]

In a reef-tank I've never heard of the use of a reverse flow through a plenum. My first instinct would be don't do it. The idea of pumping the byproducts of the bio load into an area you would have no access to for cleaning. Could turn into a costly experiment.

 

[aquariumdebacle]

A very slow return rate of a few gallons per day would keep the substrate anaerobic but I would recommend a full blast flow every month to cleanse the substrate of accumulated detritus.

 

[1fishkeeper]

Here is a link to a guy in my old club down in Utah who done one. I belive he goes through alot of detail into it and if you have any questions he will more than gladly answer them for you.
http://www.utahreefs.com/forum/forum_posts.asp?TID=24146&KW