I would make sure the tank sits for at least a week with water in it. Also let it cure for a week if possible. My dad redid a 30g once and it held water for about a week. Then one night he had water all over the ground. I then took it upon myself and tried it. It has been holding water for 10 days now. I'm debating on when to take the water out to be honest.
I am not sure of a tank that big though. Does I have a rim on it? I am sure someone will chime in who has resealed tanks as well.