I have a Sundance Maxxus. Came with the house I bought 5 months ago, the spa is about 15 years old. drained it last weekend and when i refilled it ther ewas a big leak where the PVC runs into the metal pipe right before the heater. I drained it and tried to tighten everything up. It was OK when I refilled. Now there appears to be a leak at the back of the heater housing. As far as I can tell it not coming from the PVC/Metal Pipe connection that was giveing me problem before. Do the heater housings leak? Should I look at replacing the heater, or should I be focusing in the pipe fittings? Thanks in advance for any help!