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Cultivated Reef

How deep is your sandbed


Old Gregg

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My thought is that they should be either under an inch (so they can stay oxygenated), or over 6 inches (to provide proper support for denitrification). Currently I'm maintaining 6" sand beds. A shallow sand bed is recommended for reefers that are dosing a carbon source (like vodka, vinegar, or bio-pellets).

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i started with about a 2" sand bed. however, over the course of 6 months, it became DIRTY so i've been slowly syphoning out the sand as i do water changes. i now have like 1/2" of sand. my plan is to put a very thin layer of special grade reef sand on top to prevent any sand blowing.

 

 

my issue is with the sand itself. i can't figure this out but for the past 3 months there's been a constant brown 'algae' (almost slimy but its not slime) sitting on top of the sandbed. everytime i clear most of it, within hours it'll be back. i dont really know why this is happening ;\

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the sandbed in my reefbowl is about 6 to 8 inches deep. annually I take the vase and sit it in a sink then pour twenty gallons of water through it to lift out all the detritus. If a shrimp gets flushed out I'll put him back in but pretty much everything else goes down the drain and the system starts fresh for another 12 mo go. tons of life is left still in the bowl, this just takes out some excess but what it really does is clean the sandbed for me without having to take out the rocks and corals. its nice to have a tank you can lift completely full in one hand...

 

an additional step I take to manage very deep sand beds in pico reefs is only feed the tank when a water change will be coupled to it. No waste sits on the bed and gets uptaken like the daily feeding cycle causes. Just about any animal we keep can be trained to eat heartily 2x a week vs sparingly each day. if one is doing weekly water change work then its no big deal, considering how long it will make a deep sand bed run.

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It's interesting the number of different responses on the subject. The majority tends to lean towards super shallow sandbeds of less than an inch. I personally find it very important to keep a very shallow sandbed in nano reefing. Too much is just too much of a pain to keep clean in the long run. With anything more than an inch I find it too difficult to siphon the waste out without doing very large water changes at a time because it takes so long reaching the bottom layers.

 

For someone like Rabidgerbil though, wanting a jawfish, I'd say it's well worth the extra effort hehe :) I want to try a deep sandbed in my next tank like brandon's vase. That's my next project, keeping a sub gallon pico reef absolutely and completely packed with life in every square inch including the sandbed. Something just appeals to me, creating a miniature jungle underwater lol

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6". Thats 330 lbs of Southdown sugar sand in a 60" long 100G display. The DSB is almost 8 years old and going strong. Never been stirred, disturbed of vacuumed over 1/4" deep since day one and the nitrates and phosphates are still undetectable using Salifert kits.

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the sandbed in my reefbowl is about 6 to 8 inches deep. annually I take the vase and sit it in a sink then pour twenty gallons of water through it to lift out all the detritus.

 

Brandon, don't you feel this flushing of your sand bed ruins the anaerobic nature of the deep sand bed?

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Brandon, don't you feel this flushing of your sand bed ruins the anaerobic nature of the deep sand bed?

 

better to do that than end up with a noxious sand bed. It's probably why his little pico is still going.

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Stirring a DSB does make it noxious. It releases anaerobic an anoxic bacterias that live in the absence of oxygen deep in the sand. If you need to stir anything, confie it to the top 1/4" or so when the oxygenated bacteria live.

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I tested an undisturbed sandbed/bowl of the exact same design from 2001 to 2004 on partial water changes, light daily feeding and zero blast cleanings, the usual hands off mode Id been reading about. The goal was to find nitrate reduction, naturally. They said two inches would pull it off so I did six to exceed. I fed the tank lightly with clean feed to minimize input and maximize nutrition for the tank, in my guesstimate amounts of course.

 

never got that result of zero ppm nitrate (5-15ppm avg) so in favor of longevity I abandoned the hands off/undisturbed approach but this doesn't necessarily apply to everyone's deep sand bed. There's no way Id disturb one as violently in a larger tank, one couldn't do enough water changes to properly flush it like the scale Im working in with the tiny reefs. its so easy to powerclean them. rather than risk a sulfide event, any leakage of phosphate/nitrate etc (the constituents of OTS in my opinion)-- all possibilites with a truly undisturbed bed, I opt for blast cleaning and simply using the substrate to house the animals I want for my corals/biodiversity and for surface area bacterial colonization. I don't want oxygen gradients in the bed even though currently there are some because Im due for a blasting lol

 

oxygen gradients+ unreduced proteins/detritus=h sulfide gas in some scenarios, the dreaded blackspot in the bed.

 

larger tanks with the hands off approach to a dsb use sand stirrers to slowly accomplish the same means to an end, to distribute and recycle waste pockets and prevent deep level sinking of unreduced waste items.

 

although by some standards thats counterproductive because they poop right back in the bed. blast cleaning was the only real export cheat I could think of to get the max lifespan with the least work, for a dsb pico reef.

 

 

one way to low/no detectable dissolved wastes in the bare bones pico reef is the coupled feeding/water change, the constant fight against detrital loading, and being mindful of various modes of nutrient sinking within the vessel, regardless of its volume.

 

I am the biggest skeptic on the board about natural nitrate reduction, I feel the low nitrates we see are the result of export/binding/accumulation and input rates we've learned to balance. I think an insignificant amount of nitrate removal comes from live rock and sand, just my opinion, based on home geek testing. Id be alot more convinced of sand's ability to lower nitrates if we could get tanks that repeatably achieve full nitrate reduction using only rock and sand, not consistent enough to sell me on it.

 

the larger tanks have much more patience and dilution, such extreme measures aren't required. this kind of tank conduct is really only for those fixated on breaking rules just to see what will happen in the long run.

 

 

a bare bottom is much simpler, and today's variety of frozen feed make up for the natural planktors found in dsb models that the ultra-clean bare bottom tanks may initially lack.

 

and then in all fairness to the dsb keepers, the bare bottom keepers stop their observation of the tank at the level of the base rock structure.

 

within a dsb, you have the mega ant farm effect. Worms of the most amazing diversity migrate between the sandbed and the rocks, sharing habitats

 

gammarids and amphipods of every genera inhabit the caves and tunnels, there are literally thousands more animals reproducing, moving and feeding a tank that houses a dsb if one can just balance the nutrient sinking characters through any means, natural or manmade.

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