Well- I only spoke from my own experience as well. and Dave's experience is different than mine. Hell I am probably still ridiculed on some boards for using arm and hammer baking soda as a source of buffer for my tank. Thinking of the chemistry of silica based sand, it at the time didn't seem like it would hurt. How many different blends of this stuff- Who knows- and I suspect that is the biggest variable.
I do recall reading of others who have used it exclusively for 8+ years as it was all they could find.
The tank I had with "normal sand was run for 3 years". I took efforts to ensure proper seeding with animals,
Never saw "cementation". My current tank probably has about 50% of each- as I couldn't find the southdown. I tried some of the stuff from Walmart (which was one of the "new" brands in some places for southdown- it did fizzy with vinegar, but clearly had some silica sand in it and is not the same as southdown. Shannon gave me a bunch of her old sand, so I mixed that in.
Buffering capacity- you are absolutely correct about- you get zip. But that's also why it won't turn to cement on it's own. That usually requires carbonates along with proper pH along with no aggitatation??? Silica is darn near inert stuff in that regard. and why would I want to vaccum it? I won't go into possible counter points on all Dave said- some merit to some of it, but.....the point of the grains hurting sand animals I'm sure has some validity to some animals. The irratation to corals? can't say really as I never noticed a difference. There were plenty of worms that did just fine in the silica sand. If I could find some reasonably priced sand, sure I would not use normal sand.
I've done it with 150lbs and when the day comes that my only alternative is to buy $25/30# of the same stuff as southdown, I'm sure I'll do a 50/50 mix minimally- or catch people breaking down there tanks (which can be worse using a lot of old sand).
But I guess I can always call on you Dave for some Free sand?
