Do anaerobic bacteria in freshwater do the same as

[CFC]

The best thing to stir sand in a FW tank is a spiny eel, given a soft substrate these guys will spend half their life burried in the sand. Horse faced loaches come a close second too.

 

[Ed4567]

A quick search of Dr. Ron's forum on RC showed that we have basically reached the same conclusion as him:

Now, to the original question.

While a FW DSB is possible, it is not really too feasible. Most of the sand or mud dwelling bottom fauna you need are insect larvae and well..... they metamorphose into flying bugs, lots of 'em, and in your house.

In a freshwater tank, you are basically simulating a lake or pond environment, and the bottoms of these area are often quite mucky (one of the technical terms used to describe these sediments is LSO (= Loon Sh*t Ooze - and no, I am not kidding )). We really can't duplicate this environment well in our systems.

So... bottom line go with some sediment for the plants, and I would suggest a potting soil mix, but don't use a DSB.

http/www.reefcentral.com/forums/showthre...=freshwater+dsb
(I think you need to be a member).

 

[andywg]

If you were to put any DSB in a sump/fuge then the below article is very useful (especially for the salties on here).

Monaco system

I quote a contact from another forum:

The Monaco or Plenium system was invented to reduse the accurance of hydrogen sulfide by keeping the dead zone in the middle of the sandbed with nylon screen protecting it from digging fish.

The high magnesium and other ionic charged minerals in the substrate is a sign of aggrogate substrate used in marine and ARLC (African Rift Lake Cichlid) tanks (this has been done on ARLC tanks by the way).

It's a modification of the DSB.. but.. It can be used in FW and brackish tanks that dont mind the added buffers from agrogate sand..

As far as the critters to consume exess nutrients go.. you can set up a flow pattern to keep debis from settling on the bottom of the tank so they can be processed by the filtration in the tank.. UGJ's (Under Gravel Jets: cichlid-forum) are designed to do just this.

So it seems this method relies on water flowing above and below the (in this case) deep gravel bed to help the movement of water and to prevent detritus settling on the bottom and becoming a nitrate factory.

 

[Dragonscales]

The inclusion of micro life in saltwater dsb isn't only to allow the flow of water, etc but also to stop the sand particles from fusing together in a low oxygen enviroment according to many articles I've read. I cannot recall exactly but it has something to do with the bacteria secreting a glue-like substance which sticks the particles together, rendering the area useless and uninhabitable.

In regards to possible sand shifters in freshwater sandbeds blackworms are another good candidate. They live quite happily in smooth, small particled sand. I second the spiney eels too, mine are always loafing around under the sand and in combination with the blackworms they do an even better job.

 

[mellowserra]

As Navarre stated above, invertebrates or other animals help to stir up this bed and assist in some aeration and movement of water flow. The fear of hydrogen sulfide, I think, is really unfounded and if it occurs is related to overfeeding, poor circulation and use of the wrong substrate (coarse sand or crushed coral) that will collect detritus.

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I must certainly agree with the above, that fears of hydrogen sulfide are unfounded, to an extent. Although I am not using a DSB, I am experiencing quite a bit of this phenomenon with my first serious attempt at a planted tank. The lower 3-4 inches of substrate is a soil type mixture, consisting of peat and other organic materials (under ~2in of sand).

A couple times a week I go in with chopsticks to release (sometimes rather large) pockets of gas that have formed. Quite often, the gas builds and releases on its own. At first I was rather alarmed, thinking "anaerobic bacteria + bad stenchy gas = dead fish". This has been going on for months as a result of the organic materials in the "soil" breaking down (I didn't realize it would take so long for peat to finish decomposing!)

So, if the substrate is anaerobic and has been delpleted of its manganese and iron, it may turn to sulfer (which is in all the foods and is typically very abundant). And note that a by-product of the reaction is hydrogen sulfide (H2S) gas that is very toxic to all living things. The really good news is that H2S is very unstable near oxygen. As soon as H2S runs into some oxygenated water it becomes sulfuric acid, which while dangerous, it nowhere near as bad as hydrogen sulfide gas:

H2S + 2 O2 --> HSO4(-) + H(+)

As a point, H2S was found to be negligible in a study of a swamp with oxygenated water, even when the sediment levels in the swamp were very high. I think that the classic danger that is warned about is H2S gas, but my understanding is that H2S is neutralized very very quickly. So you would have to have quite a lot of stagnant H2S for it to come out of the subtrate and kill something.

[snapback]922633[/snapback]​

From my observations, the gas is not harmful to tank inhabitants, everything in my tank is in fact thriving/growing/reproducing and what not. If there is even the slightest amount of sulfuric acid being produced as the gas passes through the water, it does not touch the pH, which tends a little alkaline.