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Interesting System/Sump Set up


hlem

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So I was in cali last week. checked out this LFS. The owner had a very interesting saltwater system set up. 

 

The DT would drain into a sump/tank, with the return being at the bottom, under the sand bed. WAter isnt going up/down through baffles, and No skimmer, just everything gets pushed through the 3-4" sand/gravel bed.  all this fish seems very healthy.  He's said he's been running this style set up for 30 years with very little loss. I did not see any dead fish in any of his systems.

 

He uses this for his coral systems too. No skimmer anywhere.

 

Anyone done this before? Potential issues?

 

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8 hours ago, madweazl said:

Looks like a typical undergravel setup that was just remoted from the display. 

 

Yes youre right. How come this isnt implemented more? Actually, this was the first time I've seen it in action at that store. Seems to work very well since all his tanks are heavily stocked.

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46 minutes ago, hlem said:

How come this isn't implemented more? 

 

I expect the sand-bed-sump arrangement works best when the sump is elevated enough to put plumbing and a pump under it.  That's a more difficult arrangement for most people than a simple sump-on-the-floor setup. 

 

Also, you probably need to change out the sand or vacuum it periodically because all the detritus will settle there.  Like what most of us see in the bottom of our sumps, but more because there's no skimming or other mechanical filtration.  Not bad, just different.

 

Finally, skimmers provide a lot of oxygenation to the water.  You have to be willing to give up the extra buffer that provides when something else causes a reduction in oxygen  I suffocated some fish once when I turned off my skimmer and a noisy MP10 in my Red Sea Max.  The return pump was still running, but it wasn't enough on it's own to keep the tank oxygenated.

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  • 2 weeks later...

It looks like you'd have to use fairly large aggregate in the DSB. Otherwise you'd have gravel / sand headed into the pump causing damage or wear concerns. If the pump were placed a little higher, then (over the long term) sand and gravel would accumulate in the pipe, eventually leading to an overheated pump. Again, less of an issue if the bottom filter plate really kept the aggregate from passing into the return plumbing.

 

Another concern might be the lost volume under the tank. Not to mention trying to service the plumbing under the tank if something went wrong.

 

Otherwise, perfectly reasonable.

 

One design variation might be to put a single baffle on one end that goes all the way down to the filter plate to leave an open area on one side.Then, install a bulkhead on the side pane into this empty area and take water from there instead of the bottom of the tank.

 

 

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10 hours ago, Origami said:

It looks like you'd have to use fairly large aggregate in the DSB. Otherwise you'd have gravel / sand headed into the pump causing damage or wear concerns. If the pump were placed a little higher, then (over the long term) sand and gravel would accumulate in the pipe, eventually leading to an overheated pump. Again, less of an issue if the bottom filter plate really kept the aggregate from passing into the return plumbing.

 

Another concern might be the lost volume under the tank. Not to mention trying to service the plumbing under the tank if something went wrong.

 

Otherwise, perfectly reasonable.

 

One design variation might be to put a single baffle on one end that goes all the way down to the filter plate to leave an open area on one side.Then, install a bulkhead on the side pane into this empty area and take water from there instead of the bottom of the tank.

 

 

 

I was thinking of the same for the variation.

 

Aside from the concerns. How is under-gravel filtration compare to just standard DSB? I've never used under-gravel anything before. even when i had fresh water.

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By definition, since the flow through this sand/gravel bed is fairly robust, it's considered a well oxygenated sand bed. Thus, it'll process ammonia and nitrite, but will not do much for nitrate. For that, you need anaerobic conditions which are found in areas where flow nearly non-existent and diffusion is used to bring nitrate to the anaerobic bacteria. Those are the conditions that you'll find below the surface in live rock or a couple of inches or more into a traditional sand bed.

 

BTW, the old undergravel filters used a baseplate to create a plenum, or void area beneath the gravel substrate. Air-driven lift tubes extended down into the plenum and, using an airstone and airpump, created slow circulation pulling water down through the gravel from below the plenum and lifting it through the lift tube. This approach had a way of dragging detritus deeper into a gravel bed where it lay to rot, unless it was siphoned out. Paul B's "reverse undergravel filter turns this idea inside out: He uses the same plenum, but installs a light-duty pump on the lift tube, pushing water down into it. This creates a positive pressure in the plenum that escapes upward through the substrate. Consequently, his sandbed is likely to be fully oxygenated, with most of his nitrate processing being done in live rock and, if he's still running it, his algae trough/scrubber. 

 

Use of void spaces, or plenums, has popped up from time to time over the years. Probably the most known approach (to old timers) is the method implemented by Professor Jean Jaubert of the Monaco Aquarium some 30+ years ago. Read more about that method here. In fact, my first saltwater tank successfully implemented a Jaubert plenum....

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How do grains of sand not get through into the pump?  The plates for UGF do have holes or slats in them, so there must be some grains going through there building up over time. I would hate to have to take all of that apart to fix a problem.

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7 hours ago, treesprite said:

How do grains of sand not get through into the pump?  The plates for UGF do have holes or slats in them, so there must be some grains going through there building up over time. I would hate to have to take all of that apart to fix a problem.

That's why I have to assume that the substrate is larger than the holes. Either that, or a window screen is being used over the undergravel plate (in which case the grains would still have to be larger than the screen) which is what we used with Jaubert plenums a while back.

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