Refilled tub and next day GFCI breaker was tripped

[gigercom]

Hello all...  I have a 425 gallon White Springs Spa "Little Rock" Model 9047 that is about 18 years old. It is a 220v 60amp model. 

I have minimal issues with this tub, it has worked fine for years.

I recently drained and re-filled the water for the summer months and the next day I came out and the tub was off. It had been on for months with no issues. The 60amp GFCI breaker was tripped at the panel. The last time I had issues with tripping the breaker it was the Aquatemp 26-00155 vertical heater that needed to be replaced.  It would trip the breaker as soon as I turned up the heat.  This time however, I have the heat turned all the way down and as soon as I flip the breaker back, it trips back immediately.  This leads me to believe that there is another issue at hand.

I also had replaced the continuous circ pump, but that was May 2012, so  I am guessing that this needs to be replaced again, but I wouldn't think that it would trip the breaker. and Yes, it runs all the time on this tub.  No timer unfortunately, it runs 24/7.  It is a Laing SM-1212-NHW-19 / 230v 1ph, 60hz.

I know there are some fuses at the internal panel that I will check, but I thought I would start here to see if anyone has any ideas where to start. 

Thanks in advance everyone!

[BullFrogSpasMN]

start with fuses like you mentioned, if that doesn't work you can apply the simple "process of elimination"....unplug the heater from the 'control pack' then turn on your breaker, does it hold? if that doesn't work then unplug the circ pump and try that...good luck

[Dr. Spa™ Ret.]

Probably time for another heater element. Not all that unusual for the element to become worn, and after starting up after a water change the air being purged from the system vibrates things enough to cause it to finally go out.

[gigercom]

Well It looks to be the heater... I unplugged it from the control box and turned the tub back on.  No trip at GFCI breaker and the continuous filtration pump kicked on with no issues.  All other pumps work as well.  For now I am just leaving the heater unplugged so the filtration pump can run,.. but I think Ill have to drain it again anyway since I have to swap out the heater.