Revival of RUGF including NNR ! !

[wave98]

That's pretty close Andrew. The Lift Tubes from a standard UGF should be replaced with pvc tubing and combined to a pressure manifold. There are a thousand ways to do this, and Paul's version is as good as any. Next you have to add some substrate at the bottom that won't fall thru slots in the plate. You can then add layers of successively smaller grain sizes until you get to the grain size that you prefer.

There will be a lot of controversy about layering, but it won't last long. Also about grain sizes for the majority of the substrate, and that one is a little bit stickier. My current preference is to have a goodly amount ( say 3" depth ) of .25 to 1.0mm stuff for good bacterial area, and to be conducive to small bioturbation animals, and sand burrowers. These animals are after all, why you are using substrate to begin with.

Some .5 to 1.5mm stuff at the top ( say 2" depth ) will be adequate for burrowing animals, and allow very high flow without sand storms, when applied properly.

A critter screen between the two, at about 6mm openings will keep large animals from opening up the bed down to the bottom, and allowing a major low pressure channel for generalized flow to escape thru.

Close enough for now.

> Barry

 

[Paul B]

I think a "critter screen would be a mistake. You will have to stir this thing up once in a while and you can'r stir under a critter screen. My "critters" are allo over the place including under the plates. I can look under my tank and see worm trails in the fine layer of sand that fell through the slots.
Barry, why would you want to replace the acrylic tubes with PVC? there is virtually no preasure at all. You are correct, the size of the substrate is a matter of debate. Mine is so old that is is all sizes but I think it started out about as large as rice grains.
Paul

 

[ethanriley]

Ok I got the gist, but what I don't get is why not combine DSB with the RFUGF. If you are worried about hypoxic layers because of the depth just increase the flow?

 

[Boomer]

Barry

Yes, you are correct a typo on my part it will me pretty much hypoxic and not anoxic. There may be some palces that are oxic. I corrected it thanks

See post 12 again I added some things

 

[ethanriley]

Also to go with Mojo's nutrient tranfer idea (remove it before it accumulates) which makes perfect sense to me should you syphon under the plate once and a while to remove accumulated detritus and assist the bacteria? When I used to use UGF's in freshwater I accomplished this by sticking my magnum suction hose through the tube and under the plate. I have a feeling that this would also serve to syphn the bed as well and pull more water through?

 

[wave98]

Well Paul, the critter screen would be under 2" of .5 to 1.5mm sand. And while I understand that with the low flow were talking about, detritus will not be "whisked" up into the water, High flow in the water column will keep most of it from penetrating significantly, along with various critters that keep the surface of the sand "disturbed".

In this case, I'm not sure the stirring is necessary. If stirring was preferred, for the feeding of corals it represents, stirring 2" deep should be entirely adequate.

I sure don't have the experience that you do here, but I have a similar condition of layered sand in my 1 year old tank, with no stirring or vacuuming, and no trouble whatsoever with the sand.

> Barry

 

[wave98]

Andrew, with a good filter before the pump, there should be almost no detritus under the plates. Remember, you were using a UGF, not a Reverse UGF. The UGF pulls detritus directly into the gravel. Gravel is used with UGF filters, not sand. The RUGF with sand is not going to get very much detritus in it. It will take a very long time for any to collect.

I would prefer to use a finer filter than Paul's sponge, but that will require more frequent cleaning. Using the output from the skimmer should help a bit here, and there are other options as well.

> Barry

 

[Boomer]

Barry

You menitoned diatom filter, that is what I used just before the water entered the RUGF, a Vortex. That will take things down to 1- 2 microns and in time will be submicronic. They also have a RUGF, but it is about the worst design there is :lol:

The Eheim, the one I used, has a flow control so flow rate into the RUGF can be controlled.


http://www.diatomfilter.com/products.htm

http://www.marinedepot.com/md_viewItem.asp?idproduct=EH3540

 

[Paul B]

Barry, you will not have a problem with a one year old anything but I think of things longer term like ten to twenty years. I would not want to take this thing out after two years to clean. I really think my RUGF can run indefinately. 35 years is close to indefinately but I still want to eliminate that 25 year cleaning also.
Boomer is totally correct that a diatom filter would negate cleaning anything but IMO it is too efficient for a reef. It removes everything. Thats why I only use it occasionally.
As for a DSB with a RUGF, I doubt it. A RUGF will push that fine sand all over the place and even if it did not do that it would eliminate any benefits of the DSB. Two seperate un-combinable concepts.

 

[Boomer]

Paul it will not move the sand if you use a Eheim system The real issue with the sand is that it is to restrictive

 

[wave98]

Barry, you will not have a problem with a one year old anything but I think of things longer term like ten to twenty years.

Agreed, 1 year is not a fair test, but many people have ended up with algae and cyano, and algae mats, and clumping etc. in even less than a year. Not so in my tank. 1-2mm at surface with high flow and critters is why.

I agree on the diatom as well.

As for a DSB with a RUGF, I doubt it. A RUGF will push that fine sand all over the place

I don't think so. Sand, even when fine, is much heavier than organic detritus. I qualified the sand to be over .25mm in size. What people think of when they hear "sand" is anyones guess, but "southdown" for instance includes a good portion that is as fine as flour, and that is about 14 times finer than .25mm.

.25mm is still 2.5 times as large as the low range of "oolitic" as well. Even if it weren't, it would not be pushed up thru a 2" depth of .5 to 1.5mm grains.

and even if it did not do that it would eliminate any benefits of the DSB. Two seperate un-combinable concepts.

How so ? I don't see why. Please explain.

Boomer, the Ehiem appears to have strong plates, but the price is ridiculous. Thanks for the links.

> Barry

 

[wave98]

When a person says "sand" in reef keeping, they need to specify the size. That has rarely been done, and the resulting confusion is monumental. Composition is important as well, but we haven't made it past size yet.

The size that works with a specific mechanical version of system will be the right size. There are many considerations. I believe the sizes I have specified, are the right sizes for the functions they perform at various depths in the bed. Layering has never been popular, but I've never heard a convincing reason why.

> Barry

 

[Boomer]

Barry you get what you pay for and this filter has engineering behind it. Eheim does not make cheap stuff, it is German.

So everyone understands what sand is and is not. We can not be just making up numbers but need to stick to a std. But when I think of sand Barry it is as you put it, what most beaches are made up off

http://www.eos.ubc.ca/courses/eosc221/sed/sili/siligsize.html

 

[wave98]

Thanks for the link Boomer, those are the numbers I'm used to. The question is, at what GRADED size of sand, is the bed going to be "too restrictive".

> Barry

 

[Boomer]

I agree on that 100%. But in nature, layering is important, that is well pointed in studies of the meiofauna and microfauna. Ron ( and most know I can not stand Ron) wrote about it long ago and I agree BUT. The real question is how important is it in a reef tank and if you are messing with it or have allot of sand siffters there will no be much layering.

 

[piercho]

This is a good thread and I'm glad to see Paul participate as he has the wieght of experience on this topic.

Heater cables do not have to go in the tank they can go under the tank

This is a very good idea that had not occured to me. Most flexible insulators in the hobby IME don't last too long before they begin to degrade. I expect years of use out of heating cable, but not decades, and we are talking about extending the life of the tank for decades here. Several companies make electric heating grids for use under ceramic tile. It should not be that hard to adhere the grid to the tank bottom, and insulate/reflect it up with foil-bubble-foil or foil-sided foam board.

What is the lower limit for the grade of gravel for RFUGF? 5mm? Smaller? If you go too low I think that flow channels will quickly form and "short-circuit" the bed, you'll end up with a Jaubert with a few high-flow regions.

 

[liveforphysics]

I'm curious why you guys are looking for NNR? Is NNR considdered to be a reasonable method of N export still?

My favorite tank is running high flow UGF with 2" of corse crushed coral on top of it. On a salifert low range NO3 test, I cant seem to get a dectable reading now matter how hard I over feed.

Since P cant disolve out of the water into the air like N, I see keeping the bio available ratios intact to be important. With the ratios kept between 12:1 to 60:1 N ratios, the cheato I use for my sole nutrient export means is able to take not only all available NO3, but also all the PO4 with it.

If I were to facilitate NNR areas and let that N off gas, I would be messing with the bio useful ballence ratios and potentially running a risk of gaining dectable P.

Just as something to stir things up, Mojo told me that he personally thinks NNR is a bad idea. Bob Fenner also told me that NNR was a bad idea for any tank beyond amatures starting out.

 

[Paul B]

Boomer, what does an Eheim system do? Is it an Eheim filter pushing water under the plates? In my system it is just gravity that moves the water. The water is just pumped to an open container where it falls through the tubes.
Since I have one pump to feed all three tubes in a 6' long tank I can run it very slow. It has been two years since I cleaned it and even when I stir my gravel there is very little detritus trapped in the gravel.
I think it is a great system.
There was a guy why mailed me to say he used sand with an undergravel and the entire bottom would rise until the water found a weak place to push through. Not a very efficient way to go. And ofcourse that is because as you say, the sand is too restrictive.
Take care.
Paul

 

[Paul B]

Barry, sand would clog in no time with any kind of flow through it, after that it would tend to rise in places from water preasure and the water would channel. Thats what I meant about sand moving. Detritus will accumulate no matter what you do, it starts off as microscope pieces some of which is dead bacteria and it builds in size like lint does. There is very little space between sand grains and it would clog very fast.
Paul

 

[wave98]

Boomer, most of the layering is underneath the critter screen. It is the function of the critter screen, to keep animals that are large enough to disturb the layering out of that area, while allowing smaller but still beneficial animals through.

I have specified 6mm ( 1/4" ) openings in the screen thus far. The top layer of .5 to 1.5mm at 2" deep, is for the larger "sifter-burrower" to "play in". That screen size could be reduced if we find that there is a critter smaller than that we want to avoid.

I am not a fan of Ron's either. Is there information available from other sources ? I have had a hard time finding any.

Thanks > Barry