DSB in a bucket for nitrate control

[psimitry]

<a href=showthread.php?s=&postid=7511655#post7511655 target=_blank>Originally posted</a> by Ereefic
I've got a 33 gal. brute can and thinking about making a RDSB. Has anyone uses a can like this? I'm wondering how many pounds of sand I would need to just about fill it up?

Got roughly 300 gal. system. How much sand would you recommend? I would like to keep it all in one container if possible.

As far as I'm aware, a larger container can be used as long as it is a round container (the better to evenly distribute outgoing pressure).

As far as how much sand is required... I don't know to be exact. But it took about 45LB of sand to fill up my 5G container to about 2 inches below the surface. I'd imagine that the entire 50LB sack would have filled it completely.

By that logic, it should take about 330LB of sand to fill up your container to the rim. Subtract say... 15 to allow you to put in your bulkhead/uniseal at the top.

 

[scrager]

this was discussed a few pages back.

do you want to build an overly complicated system that could denitrify, or an incredibly simply system that has been shown to denitrify?

<a href=showthread.php?s=&postid=7511771#post7511771 target=_blank>Originally posted</a> by kwirky
ok, water treatment plants, with their HDR's (heterotrophic denitrification reactor), actually run the water through the media. What if one was to RUN your water through a larger grained medium that won't be as likely to clog up, let's say... carbon or gravel (although carbon has a wonderful surface area), and go for oxic denitrification?

this article here shows that there are LOADS of different bacteria involved in denitrification, some oxic, some anoxic... it's just that the oxic bacteria produce nitrites along with nitrogen, usually.

http://www.wrc.org.za/archives/watersa archive/1999/July/jul99_p357.pdf

if you were to follow Hiatt's example (link here) and place your denitrifying medium in PVC tubing, horizontally, and run your water very fast or very slow, through a series of these tubes, it could possibly denitrify...

 

[scrager]

there was a post at one point about how deep is too deep or whatever. there isn't really a depth that is too deep, but there is a point of diminishing returns.

i think it was something like any deeper than 18" won't help take away more nitrates. at that point you need more surface area at the same depth.

something to consider before you fill up a trashcan with 300+ lbs of sand.

<a href=showthread.php?s=&postid=7513185#post7513185 target=_blank>Originally posted</a> by psimitry
As far as I'm aware, a larger container can be used as long as it is a round container (the better to evenly distribute outgoing pressure).

As far as how much sand is required... I don't know to be exact. But it took about 45LB of sand to fill up my 5G container to about 2 inches below the surface. I'd imagine that the entire 50LB sack would have filled it completely.

By that logic, it should take about 330LB of sand to fill up your container to the rim. Subtract say... 15 to allow you to put in your bulkhead/uniseal at the top.

 

[Spuds725]

Regarding using a large container for a large system.....

Read the first 2 posts of this thread-- a store used a 55 gallon tank filled almost entirely with sand for this.... shape should not matter---

 

[scrager]

but a 55 gallon tank is 4 square feet of surface area and only about 20 inches deep.

compared to a 60 gallon trash can that is 3 or 4 feet deep with less surface area.

overall size doesn't matter, but surface area and depth do matter.

<a href=showthread.php?s=&postid=7514358#post7514358 target=_blank>Originally posted</a> by Spuds725
Regarding using a large container for a large system.....

Read the first 2 posts of this thread-- a store used a 55 gallon tank filled almost entirely with sand for this.... shape should not matter---

 

[onetrickpony]

Again I believe you are making two complicated
Surface area of the sand is what important not surface area container is
In aquariums you would want a large surface area for improved gas exchange
So for a DSB what would work better?
1 inch of sand over a large area or less surface area and deeper depth
I would believe that the trash can would be better
As the water traveled deeper it would have less oxygen
And that is the process that we want
Ken

 

[Ereefic]

I also have a 24x24x18 tank I could use. Thoughts?

 

[scrager]

you aren't thinking about this right. the water is not flowing through the sand it is flowing over the sand. the nitrates get down in the sand via diffusion.

the question is how far down can the nitrates diffuse? it was said earlier in the thread that a RDSB needs to be atleast 6 inches deep but any more than 18 or so is just wasted sand.

i'm not saying you want 1" of sand over a large area. you want sand around 12-18 inches deep and as large a surface area as you want. the more surface area at that depth the better.

i'm not sure if "surface area of the sand is with important not surface container is" was a typo, but the surface area of the sand is going to be the same as the surface area of the container.

what i'm trying to say is that a trash can of X diameter that is 3 feet deep in sand will not differ that much in nitrate reduction than a bucket that is X diameter and only 18 inches deep.

<a href=showthread.php?s=&postid=7515207#post7515207 target=_blank>Originally posted</a> by onetrickpony
Again I believe you are making two complicated
Surface area of the sand is what important not surface area container is
In aquariums you would want a large surface area for improved gas exchange
So for a DSB what would work better?
1 inch of sand over a large area or less surface area and deeper depth
I would believe that the trash can would be better
As the water traveled deeper it would have less oxygen
And that is the process that we want
Ken

 

[scrager]

at that 12-18 inch depth, as big a surface area you can fit the better. remember that the sand itself will only be about 13 inches deep, but that should be plenty.

people use buckets to make it easier to install and change if they need to (multiple buckets and rotate them so you don't take out the whole bed and have to wait for it to regrow).

my only hesitation with using a 24x24x18 tank would be if the bed ever crashed, which it shouldn't if you keep the water clean, but still a concern as no one has been running these things for years and years to prove their stability long term.

oh, and the strength of the tank and the ability to hold 13" depth of sand.

<a href=showthread.php?s=&postid=7515731#post7515731 target=_blank>Originally posted</a> by Ereefic
I also have a 24x24x18 tank I could use. Thoughts?

 

[onetrickpony]

The surface area of the media and container are very important
A larger media will have less surface area than sand
Increased surface area = increased bacteria
Also sand bed depth and flow are connected deeper is better
Too fast a water flow and you do not give the bacteria enough time to consume the waste products dissolved in the water
You will want too test the water before & coming out of your container
If you still detect nitrate, slow the flow down
As water flows through the sand media bacteria grow on the out side of the sand
As it travels deeper into the sand bed the bacteria consume more & more oxygen
Until it exits the bucket where the bacteria finished cleaning the water

Ammonia is converted to nitrite then converted to nitrate
The nitrate is then consumed by bacteria in low oxygen areas for the oxygen the nitrate carries
End product is N2 and Co2
Completing the process
http://reefcentral.com/forums/showthread.php?s=&threadid=846816

Ken

 

[grochmal]

Are you talking about a flow-through sand bed filter?
That is not the type we are using here, but rather the water flows over top of the sand and the nitrate diffuses down to the deeper areas of the sand bed.
You won't be able to detect any difference in nitrate level between the water entering the bucket and leaving.
It passes through the bucket too quickly.
We want the water to flow quickly so that detritus doesn't settle on the top of the sand.

 

[onetrickpony]

thank for the clarification
sorry if I confused any one
Ken

 

[trmiv]

I need to set one of these up, I've been thinking about it for awhile. I need to figure out something to please the "wife factor" though. I told her I was going to plumb a white Instant Ocean bucket to the tank and set it next to the tank, and she freaked. For some reason she doesn't think it will look good. I need to find a way to hide this thing.

 

[grochmal]

Just build a little cabinet around it and put a plant on top.

 

[trmiv]

You said "build." Ha, you don't know me very well. Buy is the word.

 

[scrager]

buy a cabinet and put a plant on top

i just realized that my mention of 'surface area' conflicts with the reefer definition of surface area in sand beds. true, smaller particles will have more surface area overall for bacteria to grow on, but that is not what i'm talking about.

i'm talking about the surface area of the sand bed...the Length x Width when looking from the top (or pi*r^2 for circular buckets). you want as much surface area as you can fit at a depth of 8-18 inches. deeper is a waste of sand, shallower might not get your anoxic zones.

 

[bguile]

I'm thinking.....

I'm thinking.....

Does anyone see a problem with hard lining the supply to and from the bucket instead of using bulkheads? I'm figuring that if I drill a hole just big enough to insert pvc pipe and silicone or epoxy it to the bucket I could spare the expense and ship time of bulkheads. I'm thinking of using a coupler on each end so that i can place and remove easily if needed. Any thoughts?

 

[scrager]

silicone would work, but you risk a leak with any and every move. I'd suggest marine goop if you go that route

you should look into uniseals though.

the input doesn't have to be through a bulkhead. you could just go over the top.

if you have room in your sump for the bucket, you can just pump water in over the top and let it overflow the rim. no drilling required.

 

[Spuds725]

Re: I'm thinking.....

Re: I'm thinking.....

<a href=showthread.php?s=&postid=7531177#post7531177 target=_blank>Originally posted</a> by bguile
Does anyone see a problem with hard lining the supply to and from the bucket instead of using bulkheads? I'm figuring that if I drill a hole just big enough to insert pvc pipe and silicone or epoxy it to the bucket I could spare the expense and ship time of bulkheads. I'm thinking of using a coupler on each end so that i can place and remove easily if needed. Any thoughts?

I second the use of bulkheads-- if you don't want to wait for shipping... You don't want it to leak for a variety of reasons...

FYI--

Ace Hardware carries 1/2" and 3/4" bulkheads-- I read this on here somewhere and found the one near me had them.

Tractor Supply Company (TSC) carries 3/4", 1 1/4", and 2" bulkheads-- I happened to find them at one near me.

I would check any type of farm supply store for plastic/PVC bulkheads...

Even if you have to have them shipped, I would wait for them--- I supply my bucket loop with a Maxijet 1200 and have a 3/4" bulkhead going in and a 1" coming out.

Regarding the excess depth-- hard to know if it helps going deeper--- I don't know what would magically happen at 18" to keep the nitrates from diluting deeper into the bed---

I suppose you could set up a plenum at the bottom of a deep trashcan and divert some flow through the plenum-- you would need a goes in and goes out for the plenum... it would have to be strong to support a 55 gallon trashcan of sand.

This may be overcomplicating the system... I don't think it would help you unless you have an extremely large system...

 

[supereri]

<a href=showthread.php?s=&postid=7528041#post7528041 target=_blank>Originally posted</a> by grochmal
Are you talking about a flow-through sand bed filter?
That is not the type we are using here, but rather the water flows over top of the sand and the nitrate diffuses down to the deeper areas of the sand bed.
You won't be able to detect any difference in nitrate level between the water entering the bucket and leaving.
It passes through the bucket too quickly.
We want the water to flow quickly so that detritus doesn't settle on the top of the sand.

Is the point that the nitrate reduction will be a gradual process thus no dectectable difference is immediately apparent?

Also due to space contraints I am considering a rectangular container. It's measurements are 18x4x18 (all measurements in inches) total capacity of 6 gallons. It looks like this will proved about 2/3's the surface area of a 5 gallon bucket. Will this provide enough surface area to be effective? This will be on a 72 gallon reef tank that has a few fish.

Also is Polyethylene safe for this use?