I found someone who is selling a fish tank and he has some rock and sand that used to be live but it’s been out of water for awhile. I’m not sure how much he has but I’d like to use it as baserock and add however much liverock and some sand to try and seed the baserock.

I’m not really sure of how this process would go. Is there anything I need to do to the rock before placing it in the tank or adding liverock? Would it need to be cleaned/cured and how? Could anyone describe the process and timeframe for doing this?

I'd scrub it, if your just starting a new tank place the rock as you like it. It may take a month or so for you to cycle you want Ammonia and nitrites to drop to 0. If you already have a tank set up put the rock in a garbage can with a pump and a heater and wait for the Ammo/nitrites to drop to 0.

what they said ^

i use roughly 50/50 mix base and live....probably more base....

i dunno bout the sand though.....ive used old sand before, but i rinsed it well before i used it....

a month is a good guesstimate on how long it will take to get "purple" again......

It'll be a new tank so just scrub the old rock with regular water, put it in the saltwater, add some liverock and let it sit until the tank cycles? Sounds good. Thanks. ^^