I could care less... no where did I say that neutralizing the acidity of H2S would render it non poisoness. My arguement is that in a DSB it could possibly help to regulate a more neutral pH in the SANDBED in the anaerobic layer only not the tank.
Ok, fine. I do care however, at least enough to defend the safety of SILICA sand, not some brown sand with god knows what impurities in it. Sorry, but whatever you put in your reef was at the most very impure silica, at the very least hardly silica at all. I'm not trying to yank yer chain or anything, but I have used good silica very long term and had no problems with it as have many others. That sucks that you got a bad sand.
One question I have though on your theory, and i'm not being facecious at all. If a dsb composed of aragonite can help regulate a more neutral ph in the sandbed, how does that explain the tendency of some aragonite dsb's to concrete? It was my understanding that only a very stagnant low ph environment could lead to this.
Anyway...
Here's a pic of the specific sand that I have used with great success.
Note the warning. ALL Silica sand should have a prominent warning on the bag, and an MSDS available. If it doesn't have the warning and MSDS, don't buy and use it, unless you are absolutely sure of the composition. No, never mind that last. Just don't use it at all.
Here is a pic of the actual dry sand. It is white and crystalline. Usable silica sand should always be primarily white/colourless. This stuff does contain quartz as well which is primarily composed of... guess what- silicone dioxide. Quartz grains may contain some mineral impurities which give it various colours, but it takes a very strong acid like HF to dissolve it at all. I had to sift through it to find any coloured grains to look at.
As an additional note, I know a glass guy who uses this same brand due to it's purity and cheapness. I'm not sure if this is available nationwide or not, I suspect it may be the same stuff Simplot quarries in Idaho, repackaged for Quikrete. The Simplot sand is very high grade and used for many industrial applications where purity is a must.
Anyhoo, yeah. Don't use brown 'silica' sand.
JM2C