View Full Version : Sandbeds can KILL????

07/07/2000, 09:39 PM
Is it true that disrupting your substrate can trash the whole tank?? I use crushed coral, does that make any difference. I hear stuff all the time and thought you marvelous people had all the answers so enlighten my ignorant mind.....hehe.


07/07/2000, 10:05 PM
Oh yes they can, mine came close. When i moved i had to take the sand out of the tank, big mistake, lost about 1/2 of my corals and now i have caulerpa out the yinyang. Be careful.

Have fun and happy reefing. "The goal in life is to reach pure happieness." Aristotle

07/07/2000, 10:07 PM
Can anyone explain why or how this happens

07/08/2000, 08:55 AM
Ok, this is a good subject. I recently put in 120 LBS of that HD tropical play sand which I really like. :) It is about 3 1/2" to 4 ". My question is so I get a sand shifter or not? I have a diamond goby in my other tank and he keeps the sand turned up all the time and has dug caves under all the LR :( Hope we don't have a earth quake out here . So should I just leave it alone or what?

Barry http://sandiegoreefkeeper.homestead.com/index.html

07/08/2000, 09:49 AM
The reason why disrupting deep sandbed may cause problems is release of accumulated toxins.

When a sandbed is not being disrupted/stirred amount of oxygen available decreases very fast deeper in the sand. Denitrification bacteria can grow in this oxygen-depleted area, this bacteria simply uses nitrates as oxygenating agent instead of oxygen (oxygen is much stronger and efficient, so aerobic bacteria always outcompete anaerobic in the presence of oxygen), reducing it to nitrogen. Well, this sounds good, but there is one problem: the nitrates must diffuse into the deep parts of sand. If sandbed is too deep, or there is no enough nitrates in the tank (well, LR is a very efficient nitrate remover), or there is no enough diffusion this bacteria would not grow, but instead another bacteria will develop using different oxygenating agents, usually sulphates. The result is production of hydrogen sulphide, a very toxic substance (other toxins are also produced as well). These toxins are stored in sandbed - because there is not enough diffusion. When you disturb such an old, oxygen- and nitrate-deprived sand you immediately release all toxins into the water and you are in trouble :(.

Ironically, the best defense against this problem is to stir sand BEFORE it is too late. That is why you need animals stirring and sifting sand. Otherwise you have to provide good diffusion through the sand layer. The third solution is to have thin sandbed :).

Happy reefing,


07/08/2000, 10:17 AM
So, going with above description, which animals are best for sand sifting without eating the important creatures to extinction in the sand bed? Dr. Ron are you out there? I read your articles on this subject and it appears that certain starfish work, but others are bad. Are the various goby's going to eat all the little creatures. I have about a 3 inch sand bed at this point, three months old. I hope to use some of this sand to seed my new 150g reef sand bed in a month or two. However, if I pull out some sand and disturb the bed it sounds as if it could crash my present setup. I currently have only snails, hermits, an emerald crab and detrivore kit from ipsf that I added early on with the brittle starfish etc. I haven't seen much going on, a starfish once in a great while. I beleive I may have lost some worms in the sand bed I could see against the glass due to temperature spike during heat wave. The spike lasted about 8 hours and then i was able to bring the temp down to reasonable temp pretty quickly, but... Anyways this is a good thread and I don't want to lose present corals when i go to take some sand to seed new tank.

07/08/2000, 10:22 AM

Well, disturbing a deep bed can cause some problems. The majority of these problems are NOT caused by the release of any particular toxic materials. Rather they are caused by the destruction and subsequent decomposition of sand bed organisms.

There is some accumulation of nutrients and toxic materials in deep beds, where they are being metabolized.

The way to absolutely ensure that these materials get into the areas of the tank which will cause problems is to disturb the bed. Once the bed is set up and functional, DO NOT DISTURB IT!!!. In a well set up bed with plenty of critters, water movement through all components of the bed is accomplished by animal movement in the sediments and in their burrows. This water movement is sufficient to move nutrients to the deeper layers and metabolized wastes out of them.

This component of the bed depends on stability for its proper functionality, and this functionality is destroyed by "sand-sifting" and disturbance.

When deep sand beds are moved, as has been indicated, there is often a release of nutrients (or put another way, food you added to the aquarium). Under undisturbed situations this food would have been metabolized and removed from the system either as gaseous diffusion or as some other export.

When the pathways for this processing are broken or altered by disturbance, the results of the incomplete metabolism -the sulphides and nitrates, make it back into the upper layers of the tank.



Cheers, Ron