Heat Exchanger and pH

The water in St. Louis County, Missouri ranges from 9.7 to 10 according to the water company, and it measures off the scale with my basic Taylor test kit. When I opened our pool just after Memorial Day, I found out that our heater was shot (bad sensors; repair cost too high and repair temporary). After doing some research, I had it replaced with a Raypak (lost most, if not all, of June).

My Ph tested high, but I didn't do anything but test it for about a month. Then I tried some powder Ph down; it barely moved. I tried again about a week later, with the same results. A few days after that, I picked up some acid and added that. I got a low reading just above 7; so I figured I was fine; the next top off of water would raise it right up.

About a week later my heater quit. The service company came out and said the heat exchanger was shot due to low Ph. The tech said it measured 6.1. I was also told that my total alkalinity was too low at 60 (I figured I was fine, since Poolmath recommended 60 to 80)

The heat exchanger has been replaced. I raised the total alkalinity to 70. My Ph is still testing high (I bought a new test kit and some strips; they all test consistently, and the tech verified my technique was fine). At the tech's suggestion, I have been lowering the Ph very slowly by putting in half the amount of acid that Poolmath recommends to go from 8.2 to 7.5 (and I measure higher than 8.2). I've done this three times without getting my pool below 8.2 let alone 7.5 to 7.8 where I want it.

I don't want to ruin another heat exchanger. I'm not doing anything appreciably different than I have before, and I've never lost a heat exchanger. Because my season was greatly curtailed, I have not added any cyanuric acid; I've just monitored chlorine and kept it in range with bleach as needed and leaving my SWCG on high. Any thoughts?

Thanks,

Al
 
Head over to the Pool School section and do some reading. Your PH must have been so bad if it ate thru the heat exchanger that quickly. I've seen it happen in a commercial setting but not a residential one.
 
I thought it was odd, but I double checked my readings. I even got a new test kit and tested one against the other. The readings matched and are consistently high. The tech that replaced the heat exchanger says the copper is getting thinner and thinner. Could I have gotten a bad one? Otherwise how low would my PH have to have been to eat through so quickly? I just don't want to mess up the new heat exchanger. Am I doing something obviously wrong?

Thanks--
 
It would need to be below 6 for a short period or below 7 for a longer period. There really isn't anything besides low PH that I am aware of that would erode a copper heat exchanger. Is it a Taylor test kit? When you add acid do you add it to the pool or the skimmer? We advise against adding chems to the skimmer to avoid potential damage to pool equipment.
 
Both kits are Taylor's. One ordered through the link here and the other picked up at Leslie's. I also grabbed some strips. All test the same. I always add acid to the pool in the deep end. I've had a pool for 10 years, and I've never had a PH issue before. Other than waiting longer than usual to correct the high PH, I haven't done anything differently. I guess I'll correct the current high PH slowly with half doses...

Thanks--

Al
 
I've been installing Raypak/Rheem heaters for a long time and they still beat the competition. The only time I have seen a leaking Raypak/Rheem heat exchanger is on a commercial pool where they didn't take care of the water at all. It leaked in about 14 months.

I would add a bypass to the piping and get your water settings right before pumping any water thru the unit.
 
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