Silver Sand

[timmystood]

Ok, i'm finally doing the decent thing and giving my Brackish Puffer tank some silver sand instead of gravel tommorrow (will be fun swapping that around!) Anyway, it's silver sand brought from an Aquatic Website... Do I need to do anything to it? Or can it go straight into the tank?

Thanks
TIMMYSTOOD

 

[jayjay]

You need to wash it.

 

[timmystood]

That it? How much usually gets taken up by the filter when the fish burry or move the sand?

 

[jayjay]

Not alot in my experience and yeah a few good washes till the water clears in about 10 seconds and then add it to an empty tank, well that's what I did.

 

[Lynden]

Beware; the gravel in a mature aquarium holds a signifigant amount of the tanks bacterial population.
It's removal will have severe detrimental effects on the tanks inhabitants. I either removed or lost all but one fish in my 33 gallon tank when I changed the gravel in it.

-Lynden

 

[jayjay]

No it doesn't, what happens in bare bottom tanks then, if most of the bacteria is in the substrate? the filter holds all the bacteria the tank needs unless you aer using a UGF. What I would do is remove fish from the tank to anotehr tank or bucket put heater and filter and run them on the bucket. Then empty the tank of water. Remove all gravel. Dry the tank with some paper towels. Add washed sand and add fish and filter and heater back in.

 

[Lynden]

No it doesn't, what happens in bare bottom tanks then, if most of the bacteria is in the substrate? the filter holds all the bacteria the tank needs unless you aer using a UGF. What I would do is remove fish from the tank to anotehr tank or bucket put heater and filter and run them on the bucket. Then empty the tank of water. Remove all gravel. Dry the tank with some paper towels. Add washed sand and add fish and filter and heater back in.

If it doesn't, why did my ammonia skyrocket after I changed my gravel?
Also, do you have any idea why bare-bottomed tanks either have a huge filter, are vaccuumed and water changed scruptuously, or are lightly stocked? It's because the gravel host much of the bacteria. Think about the volume and surface area of gravel compared to that of the filter media.

-Lynden

 

[timmystood]

Don't worry, most of the gravel will go back into the tank to form 'patches' on the sand to create a natural effect.

 

[OohFeeshy]

The gravel only holds bacteria if it has a food supply, thereby indicating that if that happened on your tank you must have had a less than apt cleaning regime on it. I've changed substrate in my tanks many times, and there have never been any spikes.

 

[andywg]

If it doesn't, why did my ammonia skyrocket after I changed my gravel?
Also, do you have any idea why bare-bottomed tanks either have a huge filter, are vaccuumed and water changed scruptuously, or are lightly stocked? It's because the gravel host much of the bacteria. Think about the volume and surface area of gravel compared to that of the filter media.

-Lynden

If you are relying on the gravel to form part of the filtration of your tank to that degree, then I would say you have insufficient filtration.

The surface area of gravel does become somewhat less improtant when you considere the oxygen available for bacterial growth. A filter has a constant supply of fresh water with oxygen, in the gravel it will start to run lower, thus inhibiting growth. For this reason a trickel tower filter is best as it allows enough oxygen to be available for the bacteria.

Also, consider the surface area of a sponge compared to gravel, it will have more. IIRC bioballs have something like 330 sqaure metres of surface area per litre. I very much doubt that gravel has that much, and even if it comes close, it will not have the oxygen supply to allow it to have the same bacterial population as filter media.

If you are using UGF then the bacteria will mostly live in the gravel, but in any other situation, the vast majority will (or at least should) be in the filter. I would attribute the ammonia sppike to either not enough filtration, or inadequate protection of the colony on the filter media.

Alternatively, it could have been that when changing the gravel, something that was trapped in the gravel and decomposing slowly (due to the lack of oxygen for the bacteria involved) was set free and could then decompose far quicker, thus spiking the ammonia.

 

[Lynden]

I still am not convinced. I stand by my statement that the gravel holds much of the bacteria. Not most, but many.

If you have a 1'' substrate, the gravel surface area will surpass that of a sponge. If you took a 20lb bag of gravel, and spread it on the floor evenly, you'd end up with alot gravel-covered floor.

Also, if the substrate holds so little bacteria, how is the nitrogen cycle accomplished in nature, where there are no filters, and a river/lake/ocean can easily surpass depths of 100'?

 

[jayjay]

That is done by plants and LR in nature I think.

 

[Lynden]

Your right, live rock can do it in the ocean, and plants can have some effect on it in freshwater. But even if they did do the entire job without bacteria, what about the open ocean and lakes and rivers with little plants?

 

[timmystood]

An ecosystem the size of the river/sea could never reach the waste levels needed for NitrIte etc. to rise as a ) the water is constantly being recycled and B ) many fish eat other fishes waste!

 

[andywg]

The solution to polution is dillution.

The stocking density of the wild is nothing compared to our tanks. Also, the wild has far more plant life. than our tanks.

Remember that what we call the nitrogen cycle is not a true cycle, as we add the nitrogen in in the way of food, and we take it out through water changes or pruning of plant matter. Nature has a more complete cycle. An ocean might be over 100 foot deep (even past 7 miles in places I seem to recall) but they are not stocked at the same level as out tanks. One of the reasons a reef gets away with such a stocking density is because the huge expanse of the open ocean effectively does 100% water changes every time the tide surges.

That gravel spread across the floor may surpass a sponge (though it will not match bioballs) but will still not have the oxygen required to host a full colony of bacteria.

Why do plants grow better in non UGF tanks? Because the roots prefer anoxic conditions, conditions very low in oxygen. What do the nitrobacters and nitrosomonas bacteria require? Oxygen.

Can you see here why the gravel will not be as effective as a sponge with a constant supply of freshwater? Just how much flow do you think occurs under 1" of gravel? I have ripped substrates to bits and taken loads of gravel out and never had any problems, start messing with the filters and it's a different matter.