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Re: funny white spheres and gravel

Thayer Syme asked:

> This afternoon my brother in law and I tore down a planted 10 gallon
> desktop tank.  we discovered a good number of funny little white spheres,
> about 1/8" in diameter.  At first I thought they were small snails, but
> upon closer inspection, realized that they were completely sealed.  The
> outer surface was hard, but a squeeze with a fingernail crushed the wall,
> and produced a small white cloud which quickly disipated.  Neither of us
> has seen anything like it before and we are quite curious about them.

They sound like Osmocote (or similar) beads.  The shells are 
permeable plastic and usually a little less than 1/8" in diameter.  
Originally they coated the fertilizer bead, but the fertilizer gradually 
dissolves out, leaving a hollow, white or yellowish brittle sphere.
> ------------------------------
Dennis asked:

> Today I visited 3 different pool supply shops and none of them had this red
> flint any more.  Instead they all were selling silica sand for swimming pool
> filters.  From my understanding this is the same consistancy.but is silica
> not red flint.
> Has anyone used this stuff?  Is it as good as the stuff I used in the past?
> Is it safe?  And what possible adjustments will I have to make if I switch to
> the silica?

Flint is another form of silica (color due to stable impurities), so you 
shouldn't have any chemical problems switching to silica sand.  Silica 
sand is very light-colored.  If you don't like the lighter color then you 
might consider mixing it with a darker sand or just using an entirely 
different product.

Roger Miller