[reefnJeff]

Have any of you used this system in your tanks with success and how did you construct it?

[TritonsGarden]

Had a 55G once with undergravel filter. Ran water through the filter for a few weeks then capped off the riser tubes, leaving the plenum under the sand for an anaerobic zone. System ran for a couple of years before we took the system down. No problems and low to zero nitrates.

[coylee_17]

I've read a lot on them and they used to be the standard from what I read. Just have fallen out of favour recently for newer methods. I have never used one myself, but I do think that they are a bit dated and have been replaced for a reason. Just my 2 cents.

[reefnJeff]

I heard this sytem was really good on nitrates, what was suggested to me was to put crushed coral on top the undergravel filter, then place a screen on top of the crushed coral, then live sand on top the screen, just not sure how this system works.

[reefnJeff]

What are some of the newer methods? I'm kind of old fashioned in my thoughts and age but I always believed newer is not always better.

[TritonsGarden]

Coil denitrators
Sulfur reactors
Algae turf scrubbers
Refugiums
Deep sand beds
Carbon dosing i.e. vodka, vinegar or biopellets

You name it. There are many methods with varying degrees of effectiveness.

[coylee_17]

I think part of the problem with the plenum system was that it didn't provide for a place anaerobic bacteria as there was constant movement through the substrate. This is a very important part of the nitrogen cycle in our tanks. Also they would collect detritus and become nitrate factories overtime without proper maintenance (we tend to get lazy overtime and why add more work). I've never used this system so I could be wrong.

Now a days, I think most would recommend a sump/fuge (remote area for filtration). Although all that is really needed is an area for bacteria to colonize (Live rock) and circulation. A protein skimmer can certainly help with export of wastes.

You won't find many tanks on here that are using a variation of this method.

Really to answer the question of current methods would take a text book worth, so I've tried to give an example, there really is lots out there.

[TritonsGarden]

Originally Posted by coylee_17

I think part of the problem with the plenum system was that it didn't provide for a place anaerobic bacteria as there was constant movement through the substrate.

The way I had my under gravel filter did not have constant movement through the substrate. It was seeded initially by pumping water through it then capped and sealed. The area beneath the filter became an anaerobic zone. Worked great.

[coylee_17]

Originally Posted by TritonsGarden

The way I had my under gravel filter did not have constant movement through the substrate. It was seeded initially by pumping water through it then capped and sealed. The area beneath the filter became an anaerobic zone. Worked great.

I agree! Just I don't think this is how it is designed to work.

[reefnJeff]

Interesting really! So what would be the difference between the newer deep sand bed system and this system with deep layers of sand bed over the Plenum?