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**carlrs** · August 20th 06, 11:06 PM posted to rec.aquaria.freshwater.misc

wrote:
Hi All,

A friend is setting up a fresh water tank he has been given. It's tall
rather than long and fits in a corner unit. He's not sure weather to go
for sand or gravel at the bottom of the tank. What are the pro's and
cons? Is sand easy clean?

TIA

I have used mixtures of gravels with success. The fine will settle to
the bottom while the course gravel will remain at the top. The
advantage is have course gravel to trap the larger debris, more aerobic
bacteria, and is easier to vacuum. The fine is better for Many plants
(but not all). Also with proper maintenance (regular water changes),
anaerobic bacteria can be useful for Nitrate removal, the problem with
anaerobic bacteria is when too much builds up, then the gravel gets
stirred up releasing too much poisonous gas at once. An example of this
on a large scale just happened at the Salton Sea in California, where
the bottom got stirred up by wind storms, causing a massive fish die
off. Under normal conditions these gases float to the surface and are
released harmlessly into the atmosphere.

Carl