setting up a DIY sump/refugium

[novahobbies]

I'll be using a 30 gallon glass aquarium for this. First chamber will be filtration media (floss, then charcoal, then maybe ceramic media) before emptying into the skimmer/uv chamber. From there the water will spill over into a refugium area with a LSB and live rock/chaeto algae, after which it will spill into the return pump chamber. I had a thought about the water flow I'd like to run by some people. When the water passes through the refugium, how can I ensure I get good flow through the anaerobic deeper parts of the sand bed? I thought about using a modified bubble trap baffle, either before or after the refugium, so that (1) water is forced from the skimmer chamber into the bottom of the sand bed, where it should flow up through the sand and into the refuge, or (2) use a double trap after the sand bed so water flows out of the 'fuge by means of passing under the baffle and into the return pump area.
What do you think? Are either of these methods even feasible, or am I over-thinking this and just let nature take its course by passing water over the top area of the fuge? I can post a picture of option 1 if you guys need a visual...... Can anyone help please? Thanks!!

 

[traps]

Well of course you should post a picture!
But it does seem like you're overthinking it. I can only speak from research (as I'm sure we've both done a lot) but I've never heard of any extra flow being needed for a DSB.
Let nature take it's course
(I do post because I'm hoping to set up a refuge in the next month or so and have been planning everything out, if you try something new make sure to tell us how it works though)

 

[natclanwy]

If you try and pass water through the sand it will no longer be anerobic unless your flow rate is extremely slow. Water will be transported to and from the anerobic areas naturally through diffusion (I think that is the right term). Plus I don't think you could get water to pass through the sand bed fast enough to keep up with even the smallest return pump. Are you planning on running a skimmer in the sump? If so you might be sure to leave an area for a skimmer.
I would skip the ceramic media live rock and live sand will perform the same function.

 

[novahobbies]

So here's the original sketch. Changes made have been the location of the UV filter -- that's going in by the skimmer (which is not to scale, of course) so I don't zap any pods that get blown through the return pump into the tank. So from what you're saying, I should just reverse the bubble trap in the first set of baffles so the water passes under the first baffle from the skimmer section and over the second baffle to spill into the sand bed/fuge, right?
Just trying to make sure I do this right the first time.

 

[wattsupdoc]

As mentioned do not try to force your flow through the SB. It will naturally get there. Second, get rid of the bio balls, use your rubble there instead. Pods will be alive throughout this system, they will not all get skimmed out. Third, bubble trap into the fuge should IMO have three baffles. One up one down one up 6 inches, then a space between then continue on up. This diverts the flow THROUGH the cheato instead of it just moving along the top. If you can relocate your UV do so. Put it in line with the return pump, just flowing back through the fuge is fine. If you cant, then put it in your mechanical filtration compartment, parallel to it maybe. Or, just get rid of the damn thing, it's going to nuke pods wherever you put it. In the skimmer compartment it MAY, depending on the way it is constructed, collect bubbles.

 

[natclanwy]

Doc had a good suggestion to use the LR rubble in place of the bio-balls or ceramic media, and I would skip the UV the negatives on these outweigh the positives by far when used on a reef tank. IMO the only place they should be used is in a Quarantine tank or at a LFS. Here's a link that discusses their use a little.
UV Sterilizers

 

[novahobbies]

You know, I was originally keeping the UV to take care of diatomatious algae, but (duh!) I just realized the chaeto will effectively do the same thing by outcompeting for nutrients!

Thanks -- sometimes we all need to have the painfully obvious pointed out.......
Now, that's 50 bucks that can be spent elswhere!

 

[hurt]

Looks good to me for the most part. I too would ditch the bioballs and put LR in place. Just make sure you put the skimmer before the fuge. I would make the first baffle go under, then the next baffle go over(right after your skimmer going into the actual fuge section). Putting the skimmer after the fuge will let the fuge accumulate detritus. If you put the skimmer first it will take the detritus out before it has a chance to settle into your fuge and just add to your bioload.
Before the return pump, you should only need one baffle. When I first made my fuge I did the same and put three baffles before the return pump. Once I figured they did nothing other than take up space to otherwise grow Macro's-two of the three were ripped out.

 

[novahobbies]

Well, I thank everyone for their input! Here's a rough idea of the final project:

As you can see, the UV is gone, LR in place of ceramic media (bioballs were never an option actually, just easier to draw than little hollow cylinders) and the baffles changed a bit. Upon further reading, my thought of forcing the water up through the sand bed is actually the same as a fluidized bed filter -- which is fine, but not what I was trying to accomplish! The fluidized bed would be good for ammonia and nitrites only, but as you know I'm looking for nitrate reduction as well. If I ever decide to, I can always plumb a FBF into the system later. I doubt I'll need it tho.
Anyway, once again, thanks for all the thoughts!

 

[wattsupdoc]

Your baffle design will not work. Have you calculated backwash?

 

[hurt]

And the reason why it will not work is...that your baffles(#2 and#5 from right to left) can't go all the way to the top of your fuge. Leave an inch from the top of these baffles to the top of your fuge. This allows backwash when the power goes out to be evenly distributed across the whole fuge, not just the first chamber.
Personally I don't think baffle #5 serves any purpose at all, unless you plan on your water dropping 5 inches or so into your return pump chamber. Other than that it is just taking up valuable space that could otherwise be used to grow macro's. I run 40X turnover on my fuge with a one inch drop from my fuge to the return pump chamber, and no air bubbles are returned to my DT at all with just one baffle before my return pump(#4).
To figure out backwash use the formula (L*W*H)/231. For H use 1 as one inch is typically the most your DT will drain down to the overflow teeth. So in your 55g that would be (48*12)/231, which will give you around 2.5 gallons of backwash. So with a 30 gallon fuge you can't have more than 27.5 gallons at normal operating level. Personally I would plan on running your fuge at 25 gallons normally(so roughly 5/6 of the way up on your 30g should be the tops of baffles #3 and #4. Other than that it looks great.

 

[novahobbies]

OK, I'm sorry, I actually already had that planned, sorry it didn't reflect in the drawing.

I know I said rough sketch, maybe I shouldn't have made it THAT rough.

But thank you for pointing it out, in case anyone else was also following along: the baffles absolutely are going to be dropped.
By the way, baffle five is cause....I have spare acrylic, and I want it.