I Sand

[Davehutton92]

hi i have read in some places that argos play sand can be used in an aqaurium is this suitable? and i also heard that if its too deep it can cause a build up of toxins over time ?

 

[Dutsey]

I have argos play sand in my tank and my corys and rams love it.

 

[nurglespuss]

Yep its absolutely fine, I've used it previously.

It just needs a good deal of washing as its a little dusty.

With any sand (that isn't turned over regularly) deep layers will quickly turn anaerobic, creating 'dead' zones, which if disturbed can release all manner of things.

Including species like trumpet snails is a good idea (they burrow a lot) and having no more than say, an inch is plenty.

 

[StandbySetting]

These so called dead zones are actually pretty harmless, they're anoxic and are home to anaerobic bacteria, a product of their anaerobic respiration is Hydrogen Sulfide, one of the most toxic substances on earth, on contact with oxygen it is oxidized (Our tanks contain oxygen):

2H[sub]2[/sub]S + 3O[sub]2[/sub] > 2SO[sub]2[/sub] + 2H[sub]2[/sub]0

The products being Sulphur Dioxide and Water, both harmless, but SO[sub]2[/sub] does smell, while Oxygen depletion may be a problem in the wild due to the disturbance of H[sub]2[/sub]S it isn't in aquariums as the substrate depth, area and volume is tiny in relation to the volume of water where as in the wild the ratio isn't as substantial.

In essence, regular turning or disturbance of sand isn't necessary.

 

[nurglespuss]

I must disagree there, you have the basics of the chemistry right, but forget to include the composition of the anaerobic bacteria dwelling in these zones, and also the ammonia build up that naturally leaches into these undisturbed zones, these combined will be toxic, especially to benthic fish and invertebrates, in such a confined environment as a fish tank...

 

[StandbySetting]

Any ammonia trapped in the substrate will be reduced by the anaerobic bacteria, the same applies to the two forms of nitrate and any other compounds available, the bacteria will reduce the compounds into their constituent elements, they're especially beneficial in planted aquaria as they're capable of reducing ferrous, sulphurous and manganese based compounds etc into their constituent elements making it easier for the plants to utilise them.

 

[nurglespuss]

Yes, again mostly correct, however these these zones where sand has compacted and there is very little if any water movement, do not harbour the same useful bacteria that you suggest. In a healthy substrate, there is still water (and nutrient movement - both ways) and so the effect you describe (among others) is exhibeted. In this circumstance, with little water movement, compaction and build up of by products, the bacterial load changes composition to less useful anaerobes, essentially killing off the 'good' bacteria, resulting in toxic build up over time, the bacteria that feed on sulphur based compounds are not pleasant, and upon cell death (on exposure to oxygen) release toxic internal products.

So to clarify, if there is water movement in the substrate, there will generally be healthy bacterial colonies, where areas are 'still' compacted, or restricted (by decorations for example), this will not be the case over time.

 

[StandbySetting]

and upon cell death (on exposure to oxygen) release toxic internal products.

Do you have any examples of any toxic internal products released upon cell death?

In this circumstance, with little water movement, compaction and build up of by products, the bacterial load changes composition to less useful anaerobes

Do you have a paper or journal referencing this? I'm interested in reading up on it.

 

[nurglespuss]

Yep sure, there's plenty of older info in environmental/ecology etc. text books, and theree are plenty of papers referencing waterways, particularly lakes etc. I'll see if I can dig up an interesting one from the database, but (as is usual with aquarium based info) there's nothing aquarium specific (though it still applies).

edit: In the mean time look up Anoxic substrate zones, which are a result of compaction/organic build up etc.

2nd edit: Through sheer laziness and accident, this quick description lifted from elsewhere pretty much sums it up:

"Most of the toxic materials in anoxic substrates oxidize to harmless forms as they diffuse upward through the better-oxygenated levels, so get "neutralized" or rendered harmless before they hit the water column itself. The tank problems from such tend to be from disturbance to the substrate, from fish or from fish-keepers - which releases toxic stuff before it is oxidized by digging or stirring up such areas."

 

[StandbySetting]

While it is true that it still applies, it is only to some extent, the differences being that aquarium substrates tend to be only an inch or two thick, whilst in lakes they're generally more than a foot deep, and at a higher pressure, the ratio of substrate to lake over a given area in a lake for example could be 100 litres of substrate per 100 litres of water, where as in an aquarium it could be 5 litres of substrate per 100 litres of water, I hope that makes sense, but my point being that if there are any toxic compounds that are disturbed they'll be sufficiently diluted in order to not cause problems.

I've yet to see any one come across any problems in the hobby due to anoxic pockets, most of the information comes from papers published on lakes and people apply the same information, but the conditions are vastly different so the application of this information isn't accurate.

 

[nurglespuss]

Ah, the problem you face is scale and containment, while your summation is correct that lakes opperate on a larger scale, the principle still holds true, in fact perhaps more so, because of the reduced scale of the environment. You need far, far smaller quantities of toxic elements within the confines of even a large aquarium, in order to affect fish (a good example is the relatively (almost homeopathic) quantities of most medications applied to fish tanks).

Through a life times experience, I've come accross instances of such anoxic zones having just such an effect, and have even encountered once personally (in a long established, large tank) where a large plec unearthed such a zone killing 90% of the aquariums inhabitants.

In a restricted environment, which is continually cycled, such effects will be maginified many times over in much shorter spaces of time. So yes, the same principles that hold true for lakes and large water bodies, also hold true for aquariums.

 

[Tizer]

Interesting in theory, but chances of it happening in real world home aquariums....pretty small. For every one person thats seen this happen, im pretty sure there are 10,000 others who havn't Its never been a concern of mine anyway

 

[raptorrex]

Interesting in theory, but chances of it happening in real world home aquariums....pretty small. For every one person thats seen this happen, im pretty sure there are 10,000 others who havn't Its never been a concern of mine anyway

well put.

 

[mattyp84]

argos play sand is amazing, just wash it well and its amazing for the price, 3 quid i paid for a 15kg (i think) bag and i have a 3rd of the bag left, much cheaper than the stuff in LFS

 

[This Old Spouse]

I'm still trying to figure out if it's best to stir up the sand or leave it alone and pray none of my fish disturbs it and kills all the rest!