Are the risks of having a deep sandbed exaggerated?

[Randy Holmes-Farley Verified Community Expert]

It is not so much water moving through the sand but more the nitrates moving into the sand by concentration diffusion.

My concern with that expectation is that organics must diffuse in as well, despite having a lower diffusion constant and oxygen not diffusing in despite having a higher diffusion constant.

If sand beds reduce nitrate, I don’t see how the mechanism can be simple diffusion of these components.

 

[IceNein]

I'm not really concerned about any "risk" from them, but I'm also skeptical that they provide much benefit unless water is somehow encouraged to flow through them (plenum, reverse flow etc.).

I had one for a while. I didn't think it did much good or bad, and removed it. :)

I looked into this, trying to separate the facts from the legends, and I came upon an older article that talked about needing the sand bed to be filled with lots of life so that water and detritus could move through the sand bed, because the actual flow of water through the bed, as you mentioned, is basically negligible. Without something actively turning over the sand bed, there is no flow through it.

This article is worth reading and consideration, IMO.

https://reefkeeping.com/issues/2003-06/rs/feature/index.php

 

[brandon429]

Nobody can evaluate what sandbeds do as risks from their own setups. To learn you've got to sell others on letting you work their tank remotely. Do transfers, upgrades and sandbed swaps without any rinsing

Collect all the jobs in one thread

By page ten we will know the truth


I read that article when it came out and I never saw any of it apply to home systems. Fantastic oceanic study is how I read it.

How are we even able to evaluate performance? In nitrate kit comparison threads everyone is usually way off from a given test sample

Without accurate nitrate detection we're all guessing. When nitrate kits align I'll expect those threads to streamline too. Not being harsh just realist

Sandbeds in my opinion are dangerous in about 5-10% of presentations. From that article nothing warned me about dangerous sandbed handling risks in reef tanks, that's why I think it's more geared towards oceanic studies

 

[areefer01]

I looked into this, trying to separate the facts from the legends, and I came upon an older article that talked about needing the sand bed to be filled with lots of life so that water and detritus could move through the sand bed, because the actual flow of water through the bed, as you mentioned, is basically negligible. Without something actively turning over the sand bed, there is no flow through it.

This article is worth reading and consideration, IMO.

https://reefkeeping.com/issues/2003-06/rs/feature/index.php

The fun times at both reefs dot org and reef central of old.

Edit: how many of you remember Southdown Sand. Best reefing deal to date in my opinion.

 

[mook1178]

My concern with that expectation is that organics must diffuse in as well, despite having a lower diffusion constant and oxygen not diffusing in despite having a higher diffusion constant.

If sand beds reduce nitrate, I don’t see how the mechanism can be simple diffusion of these components.

If you have the right fauna in the bed that turn the top layer over, the organics get down there.

 

[mook1178]

My concern with that expectation is that organics must diffuse in as well, despite having a lower diffusion constant and oxygen not diffusing in despite having a higher diffusion constant.

If sand beds reduce nitrate, I don’t see how the mechanism can be simple diffusion of these components.

Another thing to think about here, is that the O2 is diffusing, it is just getting used up as it diffuses into the top layer.

It really depends on the top layer fauna to overturn the sand and creating their own organics. I do not a believe a DSB with little overturn works as well as one with lots of overturn.

 

[PPBlimpy]

I agree you need a descent sand crew. Every tank I have set up always has had a horseshoe crab. They are little bulldozers. they can be tricky to keep. My current one I got at the size of a quarter and had him in a 13.5g and got him to eat frozen brine as soon as i got him

He has molted 4 times and about 2.5" across and happy in my 125.

Back when i has my last deep sand bed I had great luck with sand sifting stars, i would like to think there is more life for them to eat. I have not had one in my current tank with a shallow 1-1.5" bed though

 

[KrisReef]

This thread reminds me of a well. How deep does a well have to be? How do you keep your well clean? How does a well work? Does it work well?

Lots of parameters and opinions with the only direction being "Keep it Clean" because this is a family site. :face-with-hand-over-mouth: :cool:

Wishing everyone a fine discussion about a deep subject with lots of potential.

 

[ChrisRD]

Someone mentioned it already...a lot of folks used this stuff back in the early 2000s. There were always big debate threads about DSBs on RC and Reefs.org back then. Personally I found it to be a pain...too fine, made it hard to have enough flow IMO.

 

[PPBlimpy]

I just used whatever sand I had. I bought a lot of used tanks,
I would take whatever sand was in these tanks and rinse / bleach/ rinse and dry and then put it in my tank.
Never cared for the super fine stuff, i did run the crushed coral but it was always just mixed in.

this is the same for my current tanks. actually spent last night cleaning a bunch of sand for my new tank

 

[56longroof]

I"ll add another dimension to this conversation. Plenum or no plenum and why?

 

[vlangel]

I set mine up with sand from the beach and dry rock. Granted it was wet sand so had the bacteria, but it was in the tidal zone with lots of wave action, so not much in terms of worms and such.

Still, what I would have given to get sand anywhere in the ocean. I am jealous.

 

[vlangel]

I"ll add another dimension to this conversation. Plenum or no plenum and why?

I have never utilized a plenum although I believe that they can be very effective.

 

[56longroof]

Still, what I would have given to get sand anywhere in the ocean. I am jealous.

TBS has live sand. That's what I used in my tank.

 

[56longroof]

I have never utilized a plenum although I believe that they can be very effective.

I put one in my tank. Depending on what source you read they can be effective or not necessary.

 

[CoastalTownLayabout]

I"ll add another dimension to this conversation. Plenum or no plenum and why?

I never saw much difference. Plenum a few extra DIY steps to set up.

For a small to medium sized set up either is hands down the easiest system for a beginner if using fresh live rock.

 

[Randy Holmes-Farley Verified Community Expert]

The fun times at both reefs dot org and reef central of old.

Edit: how many of you remember Southdown Sand. Best reefing deal to date in my opinion.

I still have some. Lol

 

[sgdnycct]

Great topic! I’m all in on DSB!

I’m on my second setup using a DSB. I’ve always used a plenum so I can’t compare with/without. My tanks have been FOWLR’s (with soft, zoa, shroom) and have done great with DSB + Refugium w Chaeto + minimal water changes.

I feed a lot- phosphates and nitrates are consistently low. I change the total volume of water no more than 1X per year. Lots of life keeping my mandarin and checkerboard happy and fat. I use reef quality light to keep the algae growing in as many varieties as possible.

When I upgrade I take the old sand and use it as lower level for the new tank and cover it with fresh sand for the top layer. I do remove the top inch or so to seed the aerobic in the new tank. This helps quickly introduce life. Risk is that the aerobic life will die being on the lower layer and that already introduces waste. But I consider it food for the DSB.

I add live sand and rock from other systems once/twice a year to keep up the variety in the ecosystem. My biggest worry is introducing something bad when I seed from other systems. Quarantine or rinsing is not helpful as too much life dies off and the point is introduce variety.

I do have to keep an eye on chemistry but I feel the benefits outweigh the costs. I’ve never done a full on reef with delicate/high maintenance corals so I can’t speak to a DSB for those situations.

Much lower maintenance than my prior old school approach of water changes + protein skimmer.

 

[PharmrJohn]

The horror stories are always passed on information. To date I have never heard any first hand accounts of a DSB crashing a tank. There are always underlying causes that usually are due to neglected tanks. The benefits of a DSB are incredible in that it is very effective at nutrient reduction and it simplifies tank maintenance. No high tech gadgets to maintain or monitor. I had one back in the 90's and it made me a believer. My current set up has a 5-6" DSB and my nitrates struggle to reach 10 ppm with alot of fish and feeding heavy 3 or 4 times a day.

There is some truth to this. Myself, back when I was a regular on 3Reef, there was a lot of talk about DSB vs. ummm, Not So DSB. Never knew anyone directly who had any issues.....only the stories. But those stories have remained very consistent over the past 17 years. Same stories. Same concerns behind them. So, personally, I think there's something to it. I can't help but think that the odds of a negative outcome are greater, but on the other hand, there are definite benefits as well. Take the good with the bad........

 

[PPBlimpy]

So I am missing something here…. What’s a plenum?