Alsuchy

Newbie here needs help, or advice. I have a down east spa with gfi problems. It was all working fine untill I drained and cleaned/refilled. When I powered it up @ the gfi panel, it started, got to the prime and then triped the gfi. I tried it again and it imeadiatly triped. I then replaced the gfi. To be sure that was good, it triped imeadiatly. All fuses are good, and I tried with all pumps and the ozone, light Ect. Unplugged, and the gfi still triped. I then tried the whole system with a non gfi breaker, then everything powers up normal. Any ideas? WHAT GIVES!! Is the board bad, how do I check and find a power leak to ground? Al