[Sueet]

I am very interested in creating a DSB for my next tank... it is a 90 gallon, and it is pretty deep, so I think it would be a great candidate for DSB..... However, and maybe I'm just reading the wrong places... I find myself unsure of the exact mechanics and construction of the DSB..... Also, I often see mention of a "Plenum" when DSB's come up too..... I can't seem to find out exactly what that IS. I think.. that a plenum means an area under the substrate where there is no substrate, only non-oxygenated water? How is this accomplished? Eggcrate? I have an old unused UGF... it's not quite the same size as the tank, but could I just put that under there? SHOULD I put it under there? What would be the best (in terms of maintenance AND optimum water filtration) way to build this DSB? I expect to use probably 6, maybe even 7 inches for the substrate..... and I have already purchased fiberglas screening to go between the lower layer of the substrate, which I was going to make crushed coral, and sand (is a particular size better? That "special grade reef select" looks too big to me?)
This tank will also have a small refugium, and I have an unused canister filter that I thought about hooking up too, but I don't know if it's necessary with a DSB? The tank is pre-drilled at the back, just two holes, with an overflow box that attaches inside the tank with bulkhead fittings... a dual bulkhead overflow would be too much flow for a refugium, wouldn't it? The refugium is a 25 gal wide, with probably 17 gallons in the center as the refug. area.

This tank will probably be home to soft corals only.. well, and some few fish that are reef safe.

*man I jabber alot.. Sorry*

[Ninong]

Originally Posted by Sueet

I am very interested in creating a DSB for my next tank... it is a 90 gallon, and it is pretty deep, so I think it would be a great candidate for DSB..... However, and maybe I'm just reading the wrong places... I find myself unsure of the exact mechanics and construction of the DSB.....

Nothing to it. Dump in sand until it is deep enough and you have yourself a deep sand bed.

Also, I often see mention of a "Plenum" when DSB's come up too.....

A plenum is a different method entirely.

I can't seem to find out exactly what that IS. I think.. that a plenum means an area under the substrate where there is no substrate, only non-oxygenated water?

Yes, a plenum system has a void under the substrate and the substrate above the void is divided by a mesh screen into two layers.

How is this accomplished?

Small sections of PVC, anything that will create about a 1" layer of undisturbed water beneath the substrate.

I have an old unused UGF... it's not quite the same size as the tank, but could I just put that under there? SHOULD I put it under there?

No! You should donate it to Goodwill or use it for target practice.

What would be the best (in terms of maintenance AND optimum water filtration) way to build this DSB?

One way would be to dump in enough Southdown (Oldcastle) sand until the sand is the depth you desire. Southdown is a good mix of particle sizes and it is extremely cheap if you can get it where you live. If you can't get it, you can use any fine particle aragonite sand such as ESV's oolitic sand for 60%, use something a little bit larger (sugar sized) for 30% and something larger still for 10% -- blend well and dump into aquarium.

I expect to use probably 6, maybe even 7 inches for the substrate..... and I have already purchased fiberglas screening to go between the lower layer of the substrate,

No, no, no!!! No screening of any kind! That's a plenum, not a DSB.

which I was going to make crushed coral, and sand

Absolutely, positively, no crushed coral!!!!!

(is a particular size better? That "special grade reef select" looks too big to me?)

You could use no more than 5-10% of Carib-Sea's special grade reef select mixed in with finer particle sand if you like.

This tank will also have a small refugium, and I have an unused canister filter that I thought about hooking up too, but I don't know if it's necessary with a DSB?

A refugium would be nice. The canister filter would not be needed but you could use it to run carbon or something like that on occasion.

[Sueet]

Ok, Ok..... NO crushed coral... curious tho,,, why? I thought it was a good buffer for the water? And I was talking about only a thin layer underneath all the sand..... And I was told I should put the screening down over the bottom two inches to prevent digging critters from getting all the way to the bottom?

Well, anyways... I checked my local Home Depot.... they don't have southdown or Old Castle.. they have Michigan sand... which, being in Mich. I suppose makes sense.... but it kind of sucks, cuz it's obviously not a good sand for a fish tank.....

Does anyone on this board know of a place to get southdown, or old castle in the Detroit area? Or maybe an online seller with reasonable rates?

I wish I could say that $20. for 30lbs of aragonite sand doesn't bother me, but ... IT DOES! It alarms me to think that I need to spend $400 for sand! I'd rather spend that on living things! I would like to put live sand on the top layer, but that won't do me any good if I can't afford the under-layer

[Ninong]

Originally Posted by Sueet

Ok, Ok..... NO crushed coral... curious tho,,, why?

Because crushed coral is too large to be mixed with sand. Because crushed coral is too large to support to sort of infauna you would need to maintain a healthy deep sand bed. Because if you mix crushed coral with fine grain sand, all of the crushed coral will rise to the top within a matter of months anyway.

I thought it was a good buffer for the water?

All of it is aragonite. So all of it is a good buffer for the water. Obviously you will have many times as much exposed surface area with fine particles as you will with much larger particles, so you would get more buffering from a fine particle substrate of the same depth than you would with one composed of large particles such as crushed coral.

And I was talking about only a thin layer underneath all the sand..... And I was told I should put the screening down over the bottom two inches to prevent digging critters from getting all the way to the bottom?

That is only for plenum systems, not deep sand beds.

Well, anyways... I checked my local Home Depot.... they don't have southdown or Old Castle..

No, they don't stock it that far west.

[Sueet]

Thanks for the info, it is much appreciated.