Heater Replacement - Salt Water Pool (several BIG questions)


New member
May 24, 2020
Hi All,

My first post, so I want to start out by thanking this forum for it's help! I tried to find answers, but my questions seems semi-specific. Here goes;

I have a in ground 18,000 salt water pool. Its 8 years old and the MasterTemp 400 heater is starting to leak. I'm a certain it's salt water corrosion in the heater, which is fine and expected after 8 years (I think). The pump, filter and the rest works fine. Here are a few of my questions.

1) I have solar electricity and solar water heating in California, so in the last 8 years I haven't ever heated the pool. I use the gas heater to heat up the spa/hot tub.
Am I actually using the heater when water just flows through the solar system? I think when solar heating is on the water my flow through the heater, but the heater isn't 'running?
2) Is there an electric heater that I could get to replace the MasterTemp 400? It seems all electric in ground heaters are not recommended for pools over 10,000.
3) If gas is my only option, which would be okay, then I obviously want to get the beast heater that is most resistant to corrosion of a salt water system. I could really use some help with reccomendations.

My system is Pentair, and I like using the app to control everything. Not sure if I have to stick to Pentair to keep the app and systems running in sync?

Thank you so much, really appreciate the help. Hope everyone is safe and pool season has begun here in Northern California.


TFP Expert
In The Industry
Jul 6, 2011

The amount of salt in your pool water is NOT going to cause any issues with your heater nor cause it to leak. If the heat exchanger is leaking it is only due to poor chemical maintenance in the water. The water became acidic and ate holes in the heat exchanger.

As for the solar and heater, it depends on how the building/installer set it up. In most cases the water would flow thru the solar fist and then thru any other heater you have installed. Yes most likely the water flow thru the heater even if it is not running. That would mean some sort of bypass valve was added that is probably manually operated. FYI, the Jandy JXI gas heater has an option VersaFlo by-pass unit that can be installed. This truly allows water to by-pass the heater if the heater is not running. This saving the heat exchanger form a possible shortened life with constant water flow thru it.

You can install any heater on your system and hook it into your controller. The controllers only act an on/off switch for the units so any brand will work with what you have.

Hope this help answer some of your questions.
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