Hi, I'm a new owner of an old hot tub. The tub is a 2003 Pacific hot tub. It has been running for a couple of months now. Recently, I've been getting a FLO error intermittently (it causes the heater to stop heating). The display constantly flashes FLO and the current temperature. I've removed the filter so it isn't caused by a dirty filter. Any ideas on what else can cause this? The water level is Ok. The tub leaks about 1" per day.