Sandless Refugium

[motti]

Hey all. I had to empty my refugium, frag tank and sump a week and a half ago to complete some plumbing work and replace dry wall

 

 

 

Now that is over and it's time to put everything back in. The sand I took out was really nasty. And I was wondering if anyone runs a refugium without sand in it? And what was your experience like.

 

It's a 55g refugium. With a lot of live rock

 

 

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[treesprite]

Unless the sand is actually a DSB to control nitrate, I see no point in putting sand in a refugium.

[motti]

Would 2" be considered a DSB?

 

 

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[mogurnda]

Unless the sand is actually a DSB to control nitrate, I see no point in putting sand in a refugium.

 

+1.  As you discovered when you took down your fuge, the sand just acts as a trap for detritus.  Without sand, you can siphon off debris a lot more easily.  Unless you are growing plants with roots, like seagrasses, or rhizoids, like some macroalgae, the sand will do you no good.  Chaeto, Ulva, Caulerpa, and non-rooted Halimeda (like H. opuntia) get no benefit from sand.

 

Would 2" be considered a DSB?

 

 

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Nope.  There is a lot of debate about the usefulness of a DSB, but 2" is definitely too shallow to be of much use.  

 

Full disclosure: I am a big fan of sand, having deep beds in both my display and slug/macro/seagrass tanks in the same system.  I just found that sand was of no use in the fuge, and made it harder to control sludge and nutrients.

[Fishie]

no sand in fuge is best...easy way to keep crud away from your pumps etc in the sump too.

 

i am trying those new bricks tho in my sump

[motti]

Thanks for the info

 

 

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[treesprite]

no sand in fuge is best...easy way to keep crud away from your pumps etc in the sump too.

 

i am trying those new bricks tho in my sump

I have thought about getting some of those. I'm waiting for more other people to give their experiences with them, so by all means, share your final conclusions when you have them.

[joro]

I've never put sand in the fuge but I have experimented with different things in the tanks I've had. In the 90G, I ran bare bottom with live rock + macro algae and in the Reefer I ran marinepur spheres both with equal success. I'm in the process of building our new tank and what I've chosen is the thick marinepur bricks + macro algae as the perfect combination. 

[dpassar12]

+1 no sand. in fuges. If you want sand do a separate DSB 6+inches. I have 3 fuges and 2 DSB on my system. No issues.

[treesprite]

Do a Xenia refugium.

[motti]

Do a Xenia refugium.

Yep they grew like weed in there. Faster than the cheato

 

 

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[astroboy]

Based on my experience, a 2" sand bed is the worst of all possible worlds. Deep enough so that organics will accumulate, but not deep enough for an anoxic zone to form. Except, if you stir it up you always get a hydrogen sulfide smell so something anaerobic is happening. Sort of. Just enough to be marginally toxic to fish. 

 

A couple of years ago I was at a Capital Area Cichlids meeting where the speaker (Frank Cowherd, I think) talked about a reactor he designed to knock nitrates down to zero. The freshwater folk didn't care, but there were a half dozen saltwater people who demanded much more detail after the talk. A "We haf vaves of making you talk" sort of thing, almost. 

 

Copps: he gave a very good talk at the CAC, I think WAMAS would like to hear it if you're looking for a speaker sometime. 

 

The basic idea was from a PhD dissertation from a Dutch student from a decade or two ago which led to a big rethink on sewage treatment in Europe  (I'll post a link to the document if I can find it, it's online somewhere). Basically, rather than using sand, what you want in a 'DSB' is rock wool instead. You can get it at Home Depot or any building supply store, its the stuff that insulation is made up these days. The idea is that the rock wool has a vast amount of inert surface area for bacteria to grow on and if water flow is low enough an anaerobic zone will easily form. The rule of thumb is that the turnover time has to be no more than 6-8 hours.

 

Frank Cowherd breeds freshwater angelfish a bit south of Baltimore and to get them to spawn you need close to zero nitrates. He uses well water, I think, that has 10 ppm nitrates and it goes down to 2 ppm after running it through his reactor. Since he has other reactors hooked up to his breeding tanks themselves he has pretty close to 0 ppm. 

 

For me, turnover was the problem. I had five gallon reactor and never was able to get a 1/2 gph flow consistently. Even when I did, that equated to my 90 gallon tank going thru the reactor only once 180 hours. Of course, 'unreacted' water got mixed in with 'reacted' water so to turnover the entire tank would have taken several times that. I made some calculations, say, that my tank would reach 30 ppm of nitrates in a month if nothing removed the nitrates, and I figured my 5 gallon reactor would have basically no effect. And so it happened.

 

However, I'm pretty sure a 30 gallon reactor would have worked like a champ. Anyway, the notion of using rock wool as opposed to sand seems to work with sewage treatment for Europeans so it ought to work OK in a saltwater tank.