deep snad bed?

[Melonbob]

Can you just add sand as you go along? Right now I only have about 1" of sand in my 46g and I heard alot more would be better. Can I just add sand? How would the best way of doing this be?

[RyanG]

If it were dead sand I would think you could add some but the fine sand needed for DSBs would probably cloud the tank for at least days if not weeks and would mess up your pumps. The funnel/pvc method would be your best optionIMO but would be very tedious and time consuming.

[Rcpilot]

Use a funnel and pour the sand into a container with a tight fitting lid.

Pour dry sand into the container (2 liter bottle?) and then fill it with water. Cap it up tight and shake. Dump the cloudy water down the drain. Repeat until it's mostly clear.

Then I bet you could dump that sand out of the bottle if you hold the bottle down low near the bottom of the tank. It shouldn't make too much dust if you rinse it first. It's gonna get cloudy, but not near as bad if you rinse it first. Just like rinsing carbon before you add it.

As far as your bacterial colonies on the existing sand:

You'll be burying the old sand and thereby suffocating the existing bacteria in the sand bed. They need oxygen and they won't get any at the bottom of a 4" DSB.

BUT, I think you could add sand over time and get it deep enough to not make a difference. Add one inch of sand at a time. Or fill up one corner with 6" of sand and let it slowly settle it's way out into the tank. Wait 3 or 4 weeks for it to settle in and grow bacteria. Then dump 10 or 20 pounds in a different corner after you rinse it and waited 3 weeks.

4 or 5 times and you'd be set. You'll see a mini cycle each time, but it shouldn't be bad unless you cover the entire sand bed at once. You still need some of the bacteria on the surface to handle the mini cycle of burying some of them, so just cover about 25%-- 30% of the sand bed at once. In 2 or 3 months time, you'll have a 4" DSB thats fully established and functional at removing nitrates.

But, thats just how I'd do it. I've learned to go very slow. This is a long term hobby and 2 months to put a DSB into the bottom of an existing tank is nothing to me. Some people would probably just dump 100lbs of sand in the tank and not even worry about it for a second. Either way would probably work.

[sen5241b]

a 'snad' bed? The new thing?

Seriously, user Kevin Simmons added sand not too long ago and it introduced a disease 'marine velvet' that wiped out all his fish. You might want to avoid the type he used.

[fatman]

I just move the top of the existing sand to one side put down the new sand and then spread the old sand back over the top of the new sand. To rinse the sand before use I just cut the top out off the bag stick a water hose all the way down to the bottom of the sand and let the water run for a while. I then turn off my circulation system in the tank, place the whole sand bag into the bottom of the tank and slowly tip it to pour out the sand. I typically have to wait only 20 to 30 minute to turn the circulation back on. Aragonite sand only has a half life of about 8 to 12 months, so am putting a new bag of sand in my tank at least once every month to two months at most. It looks like it settles, but it actually dissolves. I use Coral Sea aragonite at sizes of 0.1 to 1.0 mm. 400 lbs in a 120 gallon tank then toop it with 20 pound of GARF grunge.

[UnderwaterWorld]

would another inch or two or sand in a tank make a big difference in cutting down on the algae and what not?

[Bifferwine]

Another inch or two would not make a difference if you only have 1 inch already. A DSB should be at least 4 inches deep to be effective, and even that is really shallow.

If you want to add more sand, it's not a problem to do so using any of the methods mentioned above, and every tank needs to replace dissolved sand periodically anyways, but have a 2 or 3 inch bed instead of 1 inch won't make a difference in your nitrate levels.

[fatman]

Biffers right. The standard aragonite rule of sand beds (1.0 mm or smaller in diameter) is more than four inches and less than one inch. That depth recommendation increases with larger sand sizes. In between those depths you are basically just creating a nutrient trapping store house. A depth of four inches of fine sugar sand gives you a chance at denitrification bacteria populations in numbers large enough to at least help control nitrates, a depth at 6 inches or more can actually eliminate normal accumalations of nitrates. The half life of aragonite sand in a deep sand bed and is only 12 to 18 months or less so constant replenishment is required. However, the calcium, strontium, cabonates and magnesium that make up the sand does enter the water mix so it is not lost, it is used by corals and coralline algae for growth.

[ccCapt]

WOW I thought I had a decent grasp of reef chemistry, but this is something else. Can someone be so kind and explain, in simple terms, what all this means?

Aragonite sand only has a half life of about 8 to 12 months. - What does this mean? What are the circumstances for this to take place. Please provide a reference...if possible.

so am putting a new bag of sand in my tank at least once every month to two months at most. It looks like it settles, but it actually dissolves - How does it dissolve? I understand the pH must be low, around 7, before aragonite starts to dissolve. So then this means the pH at the bottom of a deep sand bed has a pH of 7? Isn't this the basics of how a calcium reactor works? Inject co2 to lower the pH, which then dissolves the media (such as CaribSea A.R.M. - aragonite reactor media). Is your tank just a big calcium reactor?

I just move the top of the existing sand to one side put down the new sand and then spread the old sand back over the top of the new sand. - So there is no problem disturbing the dsb and no risk of releasing any contaminants? I never used a dsb, but it was my understanding they should not be disturbed. There is no problem releasing water that has a pH of 7, if that's how the sand dissolved in the 1st place?

the calcium, strontium, cabonates and magnesium that make up the sand does enter the water mix so it is not lost, it is used by corals and coralline algae for growth. - If you "use" up a 40lb bag, and that 40 lbs dissolves, once again where does it all go? You mean to say you get 20 lbs (that's 1/2 of what was dissolved...dunno where the other half might go) worth of coralline and new hard coral growth every month? Damn, your tank would be a solid chunk of calcium carbonate after a few years.

I'm not looking for any arguements, just some logical and sensible answers to these few questions.

[fatman]

**Just as it says, half of the aragonite will be gone within 8 to 12 months. Half life is a term most often used to describe the nuclear isotopes radioactivity decline with age (it is a little more complicated than that, but that is close enough). Check any other reef site (wet web media or RC) under deep sand beds if this site does not supply that data in its articles section, or ask Fenner or Calfo at the Wet Web Media site. It is common knowledge. Or should be anyway. If not just PM John, our Super, Super Moderator.


**Aragonite starts dissolving around 8.2, however that is the extreme low end. 8.0 and lower is where it realy starts disappearing. In reference crushed coral does not dissolve until a pH of 7.6 or lower. Yes, the normal buffering proceesses in a marine tank is much a kin to a calc reactor.


**This is in general, if you have a shallow bed and want to deepen the bed. For a deep bed you just add continous thin layers on top of the existingbed. No more tha a maximum 1/2 inch at a time should be added atop the existing deep bed.


**You will be surprised how little calcium is in a solid substance. there is a lot of air in calcite products as the have a low density and are quite porous. The silica that comes with all sand, even aragonite (beach san is typically silica) will be left behind. Water changes dilute what is not needed and taken up by themarine organismsin a tank. I have never heard anyone using a deep sand bed say the dissolving sand contributed to much acalcoum, carbonate, magmnesium or thorium to their systems. It si recommende with deep sand beds that the pH be kept at the 8.3 to 8.6 range where excess dissolving of aragonite can cause clumping problems, but this is genearally just a problem with commercialgrowers who do not keep living critters in ther sand beds taht stir the sands and prevent clumping.
I'm not looking for any arguements, just some logical and sensible answers to these few questions.