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Deep sand beds-nitrate reduction areas,why they may let you down!

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Deep sand beds-nitrate reduction areas,why they may let you down! Empty Deep sand beds-nitrate reduction areas,why they may let you down!

Post  liquidg 29th November 2012, 2:54 pm

Life near or above deep sand beds or similar is a recipe for disaster!


A sand bed that is said to be working well.

There is always something that indicates the bed is not what it was, like reduced life by deaths and not replaced but the remaining are doing great, more corals then fish after some time due to corals being far easier in stressed tanks, extra nitrate reduction needed via external means like bio cubes or what ever, extra water changes beyond what they were, a larger skimmer is needed and put to the system, something needs to be changed due to the bed not functioning as it was back then, there is always something that is not told or shown or thought to be normal but it just indicates things are not what they were.

A bed never gets worse then at its worst, which is still functioning to some degree, but not what it was or could have been.

The easiest way to be aware of this is to see how the ocean functions and that is not in any way like the average marine aquarium.

 If the ocean were like that, it would all be dead a long time ago!

There is no easy way of calculating beds successes, the only way is if you put many years into them and use many types in that time and remember what came of them.

For the short term or with a lot of work, substrates in your display tank are fine. But substrates in your display aquarium do several things that are not conducive to good over health of your reef life for the long term!

As organic matter permeates them this inspires with in this anoxic zone, the obligate anaerobe, this one is the main culprit for hydrogen sulphide production.

No matter how fine your particles, organics gets in and with the developing communities of creatures living in there as well, their waste is organic.

Even of you siphon off your bed, where it is under the live rock, it will produce hydrogen sulphide, its just nature.

From this you will get far to many sulphate reducing bacteria and the valuable microbes that control the nitrogen cycle, are reduced by these.

Also many protista are photosynthetic, especially the protist called velvet. Part of its life cycle is dependant on living in and one that substrate while photosynthesising its food needs via a symbiotic relationship with cyano bacteria.

White spot is also part of the second largest community with in your aquarium being protista and part of its life cycle is dependent on a substrate as well.

Carnivore worms work from substrates in their attacks on marine life as well.

External substrates of varying depths and media should not be out of your bio system set up, they are incredibly valuable as anaerobic/anoxic zones and metal conversion sinks. There is no way that I would not have them in some form in my waters somewhere, but I know from vast experiences to never have any in the display tank or some where with out protection, so that no inorganic particles or organic particles can get to them!

With correct cleaning,applied water flow and possitioning,a deep sand bed can work very well,but hobbyists rarely do this!

Firstly the supposedly helpful planktonic life including all pods, all of these shed their shells, these shells are of silica and calcium carbonate.

If there is no reasonable lighting available, then the only creature that could reduce one of these blocking types as silica, (being diatoms that make silicon from silica),they can not not reduce it and all these fall inot the deep sand bed.

As with the sands on some beaches, this builds and fills in the spaces with a deep sand bed in the aquarium where there was supposed to be anaerobic bacteria, converting nitrate to nitrogen.

This action is achieved by anaerobic bacteria taking the 2 oxygen atoms from the nitrate atom, leaving behind the nitrogen atom as pure nitrogen gas.


This thread expalns how hydrogen sulphide-sulfur.


Deep sand bed article from marine depot.


This area now produces Hydrogen sulphide and as we all know this one is not conducive to display tank life.

As your supposedly valuable planktonic life pumps out silica, so declines the nitrate converters depth as they loose ground to the more toxic gas-producing bacteria known as anaerobes below them as this mass moves upwards.

There will always be some ground at the surface for aerobic oxidisers and some area below them for anaerobic bacteria, but as time goes on this is reduced a great deal, so now you have nitrate issues and don’t dare move any live rock!

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