Sump design questions

[spieg]

Im in the process of designing my sump layout and looking for some feedback. The display tank is going to be a 125gal and the sump is going to be a 100gal long (~72x18x18). My first section is going to be for my skimmer, then through a bubble trap (although im not sure its even necessary on a sump this long), then into a refugium section, then into my return section. Im considering employing a deep sand bed in the refugium section but im open to hearing any other ideas as well. My main questions at this point relate to how the refugium and return sections are divided. Is there a need for these sections to be completely divided or is it suitable for them to share a partial volume? Which of the two designs would be more optimal? In either setup id likely be adding some live rock to the refugium as well as growing some form of macro algae.

Design 1: ~11.5g skimmer section, ~2.5g bubble trap, ~46.5g refugium section, ~23.5g return section, ~225lb 6" sand bed
http://www.unruliness.com/spieg/aquarium/reefcentral/sump1.jpg

Design 2: ~11.5g skimmer section, ~2.5g bubble trap, ~63g refugium section, ~29g return section, where ~22g of each of the refugium and return sections is shared, ~335lb 6" sand bed
http://www.unruliness.com/spieg/aquarium/reefcentral/sump2.jpg

Any thoughts? Id also love to hear from anyone that has better ideas/use for the "refugium" area when it comes to nutrient export and pod production. Thanks in advance!

[thegrun]

I'm a big fan of cheato and live rock in the fuge. I have never kept a DSB, heard too many horror stories although I know many swear by them. I would add teeth to the divider between the fuge and the return pump sections to trap stray pieces of cheato. There is no need for the bubble trap with the size (length) of the refugium. You may want to increase the size of the return section a little to handle the volume of water that flows into the sump when the pumps are off. Another idea would be to put the return section in the middle of the sump and split the drain line into two with one dumping into the skimmer section, the other directly into the refugium section. This will allow you to control the flow through the refugium (slow it down a little). I've never had issues with too much flow in my fuge section, but with a DSB, you may need to reduce flow.

[Neogenocide]

Option 1 is much better than option 2, because of evaporation. With option 2, you will have to top off the tank much more often. That point is mute though if your running a ATO.

I would also consider thegrun's statement above about putting the return in the middle. That is how I built mine and like it so far, again just make it large enough.

Scott

[spieg]

Note: the last baffle in option 2 is only 10" high, resulting in there being 5" of water ABOVE the baffle during normal operation. Its really only there at all to keep the sand out of the return pump and prevent the pump from completely draining the refugium.

Option 2 actually has more volume in the return section, 29gal vs 23.5gal(it shares the top 5" of the refugium). Also the lower baffle would avoid any kind of splashing into the return section until over 20 gallons of water had evaporated.

[drparker]

I like option one better, but also prefer the split drain with return in the center. I've tried no overflow into the return section like you have in option 2. I've had a film build up on top of the water, i believe because the micro bubbles are still acting like a skimmer and bringing stuff to the top. I agree that a big drop overflow into the return section adds bubbles back in. I've found that about a 1/4 drop is enough to stir up the top but not create bubbles in the return section.

[dakineacct]

Noob question - I have seen several sump designs that have the skimmer on one end, return in the middle, and fuge on the other end; some designs have the fuge fed from the drain from the DT, others have it fed from the return.

Wondering what the schools of thought are for each of these methods?

[Chiefsurfer]

I would split the difference between 1 and 2. Maybe put the divider half-way between one and two, with the height a LITTLE below the last height in the bubble-trap, but def higher than diagram 2.

If you will have such a large area for the fuge, I would definitely look into a sea-grass bed. VERY cool, really don't have to worry about trimming back, can have cool critters in there, however LR would probably not fit there too well. You can also have fairly high water-glow without much concern. I personally would make 4 compartments, basically adding a sock/LR compartment in the front before the skimmer if you like LR. OR, you can add it before, or behind, the fuge, for basically a LR compartment. That might not work so well tho.

[drparker]

On the side of split drain with return in the center. It allows you to have two different flow rates. Higher past the skimmer and slower through the fuge. It Also feeds the fuge nutrient rich water that hasn't just been skimmed.

On the other side they feel directly feeding the fuge can lead to detritus build up and that there is no need to have slower flow through the fuge.

I have two tanks and have both designs, i prefer the split as it allows me to feed phyto to the pod population in the fuge and cut back on flow through there for several hours but still have the main tank return and skimmer running.

[spieg]

A few follow up questions:

1. What are the benefits of having the return section in the center? Is it to be able to reduce the flow rate through the refugium? Im planning on a pretty low flow through the sump, 600-800gph or so. Given the size of the refuguium, I think that is comparable turnover to what most are doing by splitting the drain and only feeding the refugium with 25% flow or so, plus it doesnt have any of the plumbing complexities. Thoughts?

2. Is a bubble trap necessary at all in your opinion if the return is on the far end away from the skimmer in a 6ft sump?

3. Id love to see how others have set up similar sized sumps, too!

Chiefsurfer: im not opposed to sea grass, but my understanding is that it requires a pretty tall tank. Are there any specific sea grasses that can do better in a shallow tank?

Thanks for all the suggestions, keep them coming!

[spieg]

I have two tanks and have both designs, i prefer the split as it allows me to feed phyto to the pod population in the fuge and cut back on flow through there for several hours but still have the main tank return and skimmer running.
Thats a good point, I hadnt considered a situation where I might want to isolate the refugium!

[Chiefsurfer]

spieg, THAT I am not sure about. I just read a blurb about it, and it seemed VERY interesting. I read a bit, but did not go into all the specifics. I just know most systems are impractical, because most do not have anything near that size sump. I know it needs a lot of real-estate to be beneficial, but do not know exactly how much. Also, in the bay right near where I live, these sea-grass beds are ALL OVER in nature. It is in a tidal area, but in mostly very shallow areas. That said, most-likely not as shallow as your tank. I have seen them in maybe 12inches of water at the shallowest. The grass flows sideways, and I do not know if it is any worse for the ware. If you are thinking about it, check it out more. I want to say it was in a magazine article that can be found here on RC somewhere, key word being somewhere.

[spieg]

Anyone else have any thoughts? Im still undecided between return in the center and return on the end. I like the fluidness of it being on the end and everything just being sequential. Plus it greatly simplifies plumbing, may eliminate the need for a bubble trap, etc. Im not sure how often id really be inclined to take the refugium offline.

[drparker]

Depends what your plans are for the fuge, I like to cultivate lots of pods for my madarins so I feed it phyto twice a week and take it off line over night each time.

[spieg]

Since I dont really have any experience, im not honestly sure what my long term plans are for the fuge. I like the ideas of cultivating lots of pods as well as exporting nutrients so I think those will be my primary goals initially.