Sugar Sized Sand to . . . What? Sand Storm Happening .. Need some help

[Proteus]

I only did half the tank. Just what was exposed. The sand that was behind or under the rock I left as not to bring up sulphides. The sand that I pulled out was already agitated daily from the gobie 2 sea stars and snails. And I washed the chip before I put it in.

I never noticed anything out of the ordinary but my skimmer was off for two weeks as I was battling ich. The tank is 180 gallon and I pulled out about 6 to 8 gallons of sand

If you smell rotting eggs than this is hydrogen sulfide. It is very toxic and can kill fish in higher concentration. If it smells then that's not high enough to kill. As it you cannot smell it when the ppm rises.

You can add some hydrogen peroxide before you start process this will oxidize any h2s that is released. Probably a good idea to do water change also.