Bought a small bag of the black sand and doing some water testing. Washed about half cup with tap water, drained it and then soaked it in RO water. My RO water started at TDS 10. Initial test right after adding the water, the TDS of the washed sand and RO is 26. ph 6.2, kh 1, gh 1
Now 24 hours later the TDS is 38. Not testing the other parameters yet. So far I think the increase in tds is very small. I've been stirring it up every few hours. It might just be that I didn't do a through enough cleaning. I'm hoping that it's inert. I'll test the TDS everyday for the next few days.
Update after 48 hours, It's showing TDS of 36. Slight drop in TDS could be due to the accuracy of my cheap TDS meter. Looking good so far.
Last edited by RoyalFizbin; 07-17-2014 at 06:58 AM.