:fish1: Hi Juzz, I hope you meant your PH was 8.2 not 6.2, and yes your tank should be fine with using Natural Seawater and the sand collected from the reef area where you catch your crayfish. I collect all my water and sand from a similar area here in South Florida, and everything is fine with my system. After all this is the areas where our tank mates come from. Good luck with your new system. :fish1: