I use water and bleach in a 5 gallon paint bucket. It does not take much bleach and it should not need to soak for more than about 30 mins. Then dump the mix and just use water to rinse. I usually run the bucket in my bathtub with the faucet on low for about an hour or so. If you wanted to go really crazy, maybe soak in RODI
too. I don't and have not ever had issues with what little filtered water sticks with the coral when it goes back in the tank.