Sand bed
 

There are sure to be a few views on this topic. What I would like is the opinion of others on how deep of a sand bed to use on my 90 gal tank and if I should use a plenum.

I'll bite.

First, read this:

http://canreef.com/vbulletin/showthr...highlight=sand

Then read this:

http://canreef.com/vbulletin/showthr...highlight=sand

Oh boy.

All I can say is from personal experience. I started out with a DSB and ended up sucking it all out and going BB. Not regretting it one bit :-)

Beyond that, I know nothing about plenums. Sorry!

In my new tank I went for 3/4" of sand just for looks. I plan to syphon it every water change just like a BB tank. After doing some reading it turns out DSBs cannot be properly maintained in Canada where the in-fauna is unobtainable.

I have 1/2 inch in my new 60 Gal just cycling and i think i will get rid of it because even with this small quantity, the sand bed consuming so much O2 that i almost need an Ozone reactor to get my ORP to proper levels.
So BB is my choice even thogh sand looks so good.

what about sandbeds in sumps? what are people's experiences with that? I've heard mixed reviews either yay or nay, but not much explanation why for either way.

I'm nay for sand. It's purely aesthetics. I didn't find it helped any in the sump either.

After trying sugar/vodka, I'll never need another de-nitrater!

I had a DSB in my refugium. When I took it off line nitrates went from 20ppm to 10ppm.

Thanks of the insight. I am leaning more to a BB tank now.

ive also sucked the sand out of 4 of my 5 tanks with no regrets

Look at all these converters.

To think of all the fights that were put up in terms of pro-DSB. :)

Ugh - This is an interesting debate, and one that I'm VERY frustrated about primarily because my tank is already set up :P

And also cuz I have some wicked nassarus (sp?) snails in there.

What are everyones thoughts on slowly taking bits out each water change until the sand is maybe 1/2" deep?

I don't want go to BB....

For those not familiar with a plenum here is an example.

To assemble the plenum follow these directions
1. The egg crate usually comes in 2' x 4' sheets and can be found in most hardware stores like Lowes and Home Depot. Cut the egg crate to size (A pair of heavy utility scissors works well.)
2. Place the Egg Crate panel on a flat surface..
3. Attach the PVC pipe rails to the egg crate using nylon tie wraps (no metal).
4. Attach the PVC pipe ends to the egg crate.
5. Space the PVC pipe supports evenly on the egg crate and attach.
6. Turn the assembly over.
7. Cut a hole in the Egg Crate large enough for the 1" riser tube to fit into. This hole can be anywhere you want it.
8. Cover the assembly with the larger piece of nylon screening and tie-wrap in place. It should hang over the sides.
9. Cut a V-shaped grove in one end of the riser tube with a small saw. This will allow the riser to sit on the bottom of the tank while water moves freely.
10. Cut the screening where the riser tube goes and insert the riser tube with the grove in first.
11. Place the plenum assembly in the tank and center it.
Cover the plenum with approximately 1 to 2 inchs of CaribSea "Seaflor special Grade Reef Sand.
12. Lay the smaller piece of screening in the tank centered. This helps keep burrowing critters from disturbing the bottom layer of sand.
Cover the screen with the rest of the CaribSea "Seaflor special Grade Reef Sand.
13. Install a Power head on the riser tube and run it until Amonia and Nitrite readings are undetectable, then remove the power head and riser tube.

Images:

http://i163.photobucket.com/albums/t.../PlenumTop.gif
http://i163.photobucket.com/albums/t...PlenumSide.gif

I like sand but there is no doubt it's an area that causes a lot of debate. Right now I'm setting up a tank and I'm pretty sure I'll go BB, I was thinking of some sand in a refugium that sits beside my sump but other than that I think I'll avoid it. If you do go with sand I'd say look at building a coil denitrator and getting it going while your getting your tank settled in.

Doug

The main idea behind a plenum is that you run it with a power head in a new system to get your levels straight. After that you remove the riser tube and power head and the empty space under the sand bed is where your denitrafying bacteria live and do their job.

You're still not addressing the accumulation of detritus. Nitrate is one of the lesser evils caused by detritus buildup. Other organics/toxins (phosphates, gases) can build up in the presence of large detritus deposits, plenum or DSB notwithstanding.

I would not use the powerhead method myself. Nothing wrong with the riser for allowing the removal of plenum water, {very slowly}, at times. But thats an alternative way and not from the original way Dr. Jaubert published.

Plus I did the course/fine sandbed. If I did one again I would use 4in. of a course media between 3mm to 5mm. This would allow for better water movement through the gravel & plenum. Needs to be deep enough though, with the larger sized grains, so to much oxygen does not penetrate.

Plus I would limit the amount of rock to minimum and elevate what there was. This, of course, is my opinion on running one, as opposed to the plenum systems ran in the 90,s. I have not tested this yet, but others agree with this senario.

The biggest problem is the loss of 6in. of tank space. Of course the sandbed authors figure a plenum is a waste. compared with their dsb ideas. And the bare bottomed aquarists figure both are a waste. :lol: I have seen great tanks with all three. Guess it depends on what one wishes to apply to their situation, and the livestock one wishes to keep.

With the open surface area & the larger particles, one can siphon clean the top portion of gravel easily. I have no idea how one siphon cleans a fine sandbed, unless removing & replacing sections, which many seem to do now.

FWIW, I have run bare in my last few tanks and my new 90 is also. I like the control of detritus removal also. I have rubble in mine and already its trapping detritus.

I have to admit was extremely close to setting up a plenum as I described. I really wanted to see the long term possibilities when done as above. But I cant make myself lose all that space. Not to mention the cost of a decent gravel. If I could find some of the old crushed coral, around the 5mm size, that we used on our undergravel systems, cheap, I may try still. :smile:

Except any portions where you have live rock...

Thats why I mentioned above to limit the rock and any thats used should be elevated. We once talked about doing an sps tank with only a couple of pieces of rock, elevated above the plenum on piles {pipe}, and having most of the sps pieces attached to the glass and overflow. Nothing wrong with then having some extra rock in the sump, as long as it can be kept clean.

The limited use of rock in the tank, will also help relieve caclium demand with the coralline. The 4-5in. of gravel will provide more than enough biological filtration.

Of course this limits types of fish, that require lots of hiding places & rock, like many of the smaller fish & dwarf angels, etc. Once the sps grows, more hidey spots are there. I know if I was a fish, this would not be my favorite habitat, at least not at the start. :D

:P

... I just don't like substrate.

There, I said it. LOL!

When I was planning on using the plenum way I was going to have a 3" bed using Caribsea Seafloor Special Grade Sand. 1-1.7 mm diameter grain. According to them

"This grade of aragonite is specifically engineered for plenum type nitrate reducing beds.

The pore water space created by precision grading also allows maximum pH support and dissolution of calcium carbonate."

The power head was just to get the bed activated. After awhile you remove the power head and the riser.

Before you make any sort of commitment, I'd ask around on RC and check how many people have long-term success with plenums in a reef tank.

On the other hand, if you're set on plenums, then you're set. :D

Albert - what are your thoughts on reducing a sandbed in an exisiting tank? I know there are spots behind my LR that I'll not be able to get at, but a LARGE portion is in the open and removable. If I was able to get this out each cleaning and left a small amount in the front, just to keep the tank bottom covered - would this be enough to rpevent the problems with a sand bed crash?

The only reason I have brought up the plenum line of things is Geothermal Aquaculture Research Foundation has lots of tanks and nearly all of them run with the plenum/sand bed and lots are over 5 years old and doing great. They do more research and fraging than anything else. I have found this place to be a great source of info. Fragging videos, and more. It's just that I've never heard of them ever having a problem and the tanks look absolutely amazing. I've never seen tanks stuffed so solid with corals before. And all growing like mad.

Check out these 2 articles by Toonen & Wee
An Experimental Comparison of Sandbed and Plenum-Based Systems. Part 1: Controlled lab dosing experiments
An Experimental Comparison of Sandbed and Plenum-Based Systems: Part 2: Live Animal Experiments

Very good reading and full of info, this is the most intersting paragraph

Overall death rates were roughly twice as high in aquaria with shallow sediments as in deep sediment treatments. The highest overall death rates were seen in aquaria with shallow coarse sediments over a plenum, and the lowest death rates occurred in aquaria with a sandbed composed of deep coarse sediments. The treatments that were closest to the design aquarists employ for deep sandbed, Miracle Mud and Jaubert plenum aquaria had intermediate death rates. The shallow coarse sediment design that is closest to that used in Berlin systems had one of the highest death rates, and the deep coarse sediment design for which there is currently no accepted name had the lowest overall mortality (Fig. 10). We did not test bare bottom tanks, but the data clearly suggest that the shallower the sediment, the higher the mortality rate, and you can't get much shallower than a bare bottom tank!

WowOwowOwow... Cripes I had just pretty much almost for sure made up my mind for the most part to probably go bare bottom, now I'm kind of wishywashy.

Doug

[quote=DJKoop;233232]Very good reading and full of info, this is the most intersting paragraph

and the deep coarse sediment design for which there is currently no accepted name had the lowest overall mortality (Fig. 10). We did not test bare bottom tanks, but the data clearly suggest that the shallower the sediment, the higher the mortality rate, and you can't get much shallower than a bare bottom tank!
******************
I see it diferently ie, coarse sand will only trap more CR*P and kreate more problems
JM2C worth

Hold your horses folks, let's take into consideration a few facts here and their relevance to these articles:

a. These were temporary, short term installations. Hardly set up for stability. They were not cycled properly and the actual equipment selection was unrealistic. Did anyone else notice the lack of massive flow, skimmers, cured live rock, etc?

b. The fundamentals of reef keeping are quality equipments, a good knowledge base, and routine maintanance. These procedures allow one to keep up with the dynamics of reef chemistry, organic cycles.

c. Sandbeds/plenums are a nightmare for maintanance. That's pretty self explanatory. Long-term results on properly set up (equipment, cycling, stocking, etc) BB tanks are numerically superior to those of DSB/plenum orientated strategies, IME.

For real guys, look at those experiments. Who in here has a tank that even remotely resembles those tanks (either in appearance or mechanics)?

*cough cough*

I don't think the death rates in their experiments would apply to an established tank; other factors would come into play in a newly set up tank.

The thing I found most interesting is that all tanks experienced a similar level of nitrate reduction- shallow or deep substrate.

It made me re-think the value of plenums and DSBs. I fact it should make us question what we think we know about how nitrates are reduced in our aquariums. Nitrate is obviously being reduced in areas other than anoxic zones

That's all in the eye of the beholder. See what the Europeans think of the GARF tanks and... Well, no, ask for yourself:

http://www.reefitalia.net/forums/index.php?

There's a few over there who speak English.

In contrast:

http://reefcentral.com/forums/showth...hreadid=971190

As far as I can tell, none of those tanks incorporate plenums and most use some form of probiotic (prodibio, zeovit, etc) or chemical filtration (carbon, phosphate reactors, etc) to keep their tanks low nutrient. Those methods are philosophically antithetic to those of DSB/plenum flavor; however, they will support substrate.

Anyway, like I said, it's all subjective. I'm sure the GARF method works, but they have access to live substrate. That's a pretty BIG advantage over us folks here.

As far as their knowledge base and experience goes, well, my opinion is beyond the scope of this post, but you'll find some pretty mixed reviews over on RC.

Drat, I should be doing homework, LOL!

That is pretty interesting.

*puts on thinking cap*

... Okay, that wasn't a good idea, I'm going to bed now, LOL!

Later.

Wow, talk about a mature tank. Looks like someone choped a section of reef out and stuck it in there. Beyond words. How many years would it take to get growth like that? Still speachless.

First my comments on plenums are in regards to running them correctly, as Jaubert intended and not the other dozen different ways aquarists have tried, some with success but most failing.

Second if dsb does not work, have a look at the coral growth in Nigel,s FTOTM and Quinn,s tank in the journal forum. :biggrin: Both of these aquarists have run dsb,s for some time. I cant speak for them but both have told me its part of their success.

Point being, they all work if done correct and properly maintained for that particular type of system.

Remember, Jaubert used only live sand from the Red Sea in his tanks. Makes all the difference if you can get live in-fauna. The crap that came out of my sand when I sucked it out after 2 years of running a DSB was something awful :eek:

Again, thats a dsb, as compared with a plenum. I do agree with the need for getting the correct livestock for both fine sandbeds & plenums. Most of Jaubert,s system were open to the sea, so they are not really comparable also. However he did run some closed systems. I,m not sure how the detritus accumulation would be in 5mm sized gravel. Seems to be less build up than in finer sandbeds, for whatever reason. I assume it has to do with it being broken down. Plus with my described idea, its easily siphon cleaned. The dividing screen would keep the bottom portion secure.

I will find Sprung,s article for here.

If a person did decide to go with a DSB is there a rule of thumb as to what livestock you'd want to introduce? I like snails, I think they do a fine job of keeping a sand bed clean as do Kole tangs and a number of other fish. I remember reading 1-2 snails per gallon but recently saw 2 per 10 gallons the later seems a bit weak to me. I really don't know which way to go I love the look of sand however a BB would be nice as well once the glass gets covered in coraline algae.

Still undecided and getting closer to adding water...

Doug