I've been trying to fix this issue for a while now I can't figure what it is . Nothing is getting wet , the skimmer I just replaced . I replaced the heater . I run a pair of MP40's , so no power in the water there . My ATO ( Tunze 3155 is less than 6 mos old . nothing else but the temp probe from reefkeeper touches the water . I only use the reefkeeper for temperature control really . I have the heater and a fan connected to it . I have a coral box wifi doser but I can't see that tripping the GFI . I really need to get this solved before it gets hot out . I have seen a thread where someone had issues with PC4 on reefkeeper . wonder if that is it ?? Im open to suggestions at this point .