DSB in a bucket for nitrate control

[wayne in norway]

Bob Goemans is right on some accounts and wrong on others. The principle driver for flow in most dsbs is advection, not infauna. You can get a lot of value by looking at the research group headed by Prof. Markus Huettel. There are some nice models, and experiment results. I will grant that at say 10 or 11 inches down I doubt advection is doing much, and a plenum would potentitally be a positive addition.

Heaven, they even have someone doing her PhD on oxygen gradients, factors affecting of.

I have never forgiven Dr Ron for starting an article on DSB's with the comment that 90% of fluid flow in a sandbed was caused by the infauna when there is nothing at all to back that comment up.

 

[crazylegs]

Wayne in Norway- Thanks for the good reading!

So you think that sufficient advection occurs given the substrate being used for these RDSB's and the lack of large oscillating waves? Another concern would be the topography, or lack of, within a five gallon bucket. Would enough exist to support pressure related advection?

It is difficult to find specific information using google and Dr. Huettel's name. Do you have any recommended links?

One subject that both Goemans and Huettel agree on is the formation of ammonia in an oxygen depleted environment.

Thanks again!

 

[ruprecht]

A good start:

Huettel and Webster
The Benthic Boundary Layer:
Chapter 7 Porewater Flow in Permeable Sediments

 

[Eel Freak]

For the sole purpose of removing nitrates, which is more important: Depth or Surface Area? I ask mostly because I was thinking of making a bed that is about 6ft deep using a big hunk of 6" PVC pipe. At that size, I would have roughly 8.8 gallons of space to fill with sand. On a 200 gallon moderately stocked tank, which would be better, a 5g bucket or two or this immensely deep version using the PVC pipe? I've read a lot of this thread but wasn't really able to deduce which was more important... Thanks in advance for any input here!

 

[TheFishMan65]

From my understanding (no expert) there comes a point of diminishing return. At 6 ft the exchanged water is going to be minimal so it won't do you a lot of good. At the same time huge surface with no depth won't work either because oxygen will be present through out the whole bed. I have not heard a perfect depth, but it seem like from my reading it is between 6-11 inches (don't ask my why I remember 11 and not 12 - memories are strange).

So from what I read you will be better off with the buckets, IMHO.

 

[TheFishMan65]

Here is the idea (lifted from: Deep Sand Bed -- Anatomy & Terminology)

- Benthic: surface and near sub-surface sand bed layer.
- Hypoxic: low oxygen.
- Anoxic: no oxygen.
- Anaerobic: requires depleted oxygen to function.
- Denitrifying: converts nitrate into nitrogen.

Ideally I think we would want the depth at the caution bar on the right so no hydrogen sulfide is formed (I mentioned no flow earlier which may or may not be true, but I think it is valid, but maybe not as critical). Hydrogen Sulfide is poisonous so we really want to stay away from it. From what I understand this is a large cause of sand beds crashing.

The problem (I think) is that no ones knows how deep in the sand that caution bar is. But as I mentioned earlier from what I read I think it is between 6-11 inches.

 

[harlequin tusk]

I have had my RDSB up and running for about 2 weeks. Today when i took a look into the bucket, there was little black dots on one side of the bucket. They almost look like little black grains of sand. I did my best to get a picture of them. Has anyone else experienced this or have any idea what this is?

 

[ruprecht]

For the sole purpose of removing nitrates, which is more important: Depth or Surface Area? I ask mostly because I was thinking of making a bed that is about 6ft deep using a big hunk of 6" PVC pipe. At that size, I would have roughly 8.8 gallons of space to fill with sand. On a 200 gallon moderately stocked tank, which would be better, a 5g bucket or two or this immensely deep version using the PVC pipe? I've read a lot of this thread but wasn't really able to deduce which was more important... Thanks in advance for any input here!

Low flow = shallower depths of denitrification. High flow = deeper depths of denitrification.

I have not seen evidence to support denitrification at depths past 6 inches of solid sand. Although the whole bucket is full of sand, someone has not shown me how anything deeper than 6 or so inches is doing any good. I am open to learning though.

I have had my RDSB up and running for about 2 weeks. Today when i took a look into the bucket, there was little black dots on one side of the bucket. They almost look like little black grains of sand. I did my best to get a picture of them. Has anyone else experienced this or have any idea what this is?

Could be organic particulates settling and bacteria covering and mineralizing?

 

[boozeman]

There once was a man from Nantucket
who put his DSB in a bucket
he said with a grin
while scratching his chin
when it gets full of 'trates, I'll just chuck it

 

[harlequin tusk]

Should i remove these black grains? Or should i let them be? They are still there a couple days later.

 

[jumpingintosalt]

Ugh threads like this make my head hurt~ just something else I might want to do.

 

[gig]

I skimmed through almost the entire thread... I have 2 giant megaflows on my tank, the bottom 18" is water. Can I fill these with sand and get the same results? Seems like useless space anyway.

this was back on page 10 of this thread and I didn't see any answers. I see that Mr Wilson brought it up in another thread in the lage reef tanks section (1350G in Canada)...was suprised no mention of it here.

Seems like a good idea (actually a great idea)...but wanted to place it here and get comments as well...

so if I were to fill up both of my megaflows with sand up to the point where it's below the intakes, I have black acrylic covers on top of my megflows to keep the light out. Would I need to "cover" the glass so no light can get in that way? or is this not much issue as the back is ambient light that come in via a basement window, but not direct.

I have a standard 180G RR in wall setup.

TIA!

 

[KafudaFish]

There once was a man from Nantucket
who put his DSB in a bucket
he said with a grin
while scratching his chin
when it gets full of 'trates, I'll just chuck it

golf clap!

 

[outy]

not enough surface area in a overflow box to outweigh the dissadvantage of getting detritus settling in the sand. id pass on this one for sure.

I tried a 12" RDSB with a nice flow over the top. kept it running a year when this thread started years and years ago and nitrates for me didnt drop enough to outweigh the detritus trap. even 10" down there was still a ton of junk settled in.


this can be done successfully BUT dont expect amazing results out of a 5g bucket. in a 5g bucket your missing the surface area required to do a substancial job. No matter how you slice it you wont be able to substitute water changes in a FO tank because of a small amount of nitrate reduction.

those with clean water like in a successful SPS tank and using a filter sock will probably see the most benifit.

for me I found a small ball of chaeto does about 10x the amount of reduction the bucket does [I didnt test the 10x but you knowe what I mean]

 

[90g-reefer]

So I have read most of this thread but I do have one question. Has anyone used this method in conjunction with a traditional sump to help with increased bio-loads on FO tanks with larger bodied fish.

 

[Christian J]

not enough surface area in a overflow box

Didn't understand the above... In my understanding the important thing is not so much the surface area of the overflow box, what matters is the volume of the hypoxic sand zone in it, which is thought to be relatively large due to the height of the overflow's water column. Of course a slim/narrow overflow may not contain enough sand despite its large height.

 

[Christian J]

Any thoughts on Tunze's Bio-Hydro-Reactor/Riverpack? To me they seem to work like an internal RDSB, except that they use a special porous sand(?) Tunze calls "granovit". Haven't found much about them on the web except this RC thread. Maybe the lack of interest is due to the high price.

 

[ddeneve]

The RDSB method seems like it would very well with a trickle filter. It would negate the side effect of the trickle filter. A protein skimmer to a trickle filter to a RDSB seems like it would work rather nicely to control the nitrogen levels.

 

[bdbyace28]

i can never find a real good consensus on sand bed depth benefits. i have seen both deep and bare tank bottoms with success. i would say that the fluidized sand filter works at breaking down waste from my experience. i have just started using bio pellets and will see what those do in a bout a month or so

 

[biecacka]

what do you mean fluidized sand filter?
how are the pellets working for you in comparision to the RDSB
corey