Copper Piping Failure

[SherrySt]

Is it truly possible that the copper piping inside a pool heater can corrode from the Alkalinity being too low? If so, how long would it have to be low and what would the number have to be? Thanks!

[waterbear]

Low pH is the biggest factor in copper heat exchangers corroding. Low ALK does often tend to go hand in hand with low pH. If you pH is staying stable and not below 7.2-7.4 and you alk is only slightly low I would not worry too much about it. If your alk is low and you cannot get your pH to remain fairly stable then I would adjust the alk.

[waste]

Sherry, welcome to the forum! As I understand it, low alkalinity, in and of itself, doesn't corrode metals, it's acidic (<7.0) water that eats them up. However, the alkalinity is a buffer that keeps the pH from fluctuating too much, almost every time I've had to replace a heat exchanger (3 -4 a year) the pH was very far below my test kit's ability to read and the alk was also low if not nonexistant. The 2 do play off of each other, but it's acidic water that eats the copper heat exchangers. In every case that I've had to replace a heat exchanger, it's because the pool owner has a 'set and forget' tri-chlor feeder, and hasn't taken the time to test their water (once a week would have given them an indication that there was a problem), so they have high cl (and cya) and LOW pH, a very bad combo for metals like copper. As CarlD says 'keep ahead of your water; 2 - 5 min a day to test' - it's probably the BEST advice that is regularly seen on this forum!
I know a fair bit about pool chemistry but there are folks here that truely 'know' chemistry, I'll leave it to one of them to refute or amend what I've said.

EDIT: Evan beat me to the send button

[waterbear]

And I concur with everything you said!

[SherrySt]

Thank you so much for your replies. What would the proper steps be to correct the problem? Would there now be copper in the water? If so, how do I remove it?

[waste]

Sherry, to correct the problem, keep your pH above 7.0 (7.0 is neutral and won't hurt anything) though keeping the water slightly 'basic' (ie 7.2 - 7.8) is prefered. You can raise the alk and pH by adding baking soda (it will raise the alk a good bit and the pH a little) There are some expensive products available from your neighborhood pool store, but I'd suggest using the ones recommended here, that you can buy at the supermarket.
(EDIT) Sherry, mbar, knows more about this than I, but some sort of sequestering agent should keep the liberated copper from staining your pool.

Evan, thanks for the 'back-up', you are a credit to this forum!

[waterbear]

It would not hurt to have your water tested for copper and then post the test results (Not just the copper but a full set of results for FC, TC, pH, ALK, Calcium, and CYA...if they can do it an iron test would not hurt either). We can then advise you better on what to do.

[SherrySt]

I do have Ben's test kit so I can post those numbers, but I will have to get the pool store to test for the minerals in the water. I will post them tomorrow. It is raining REALLY HARD here!

[SherrySt]

I have the readings on the pool, using Ben's PS234 Kit. The pool is 22,000 gallons, inground, vinyl liner.

FC .5
CC 0
TC .5
pH >6.8 (color was lighter than lightest color0
Alk 150
Cal 550
CYA The dot disappeared as soon as I started pouring water into the tube.

The heat exhanger in the heater has apparently corroded completely thru. The pool stores says it's due to low pH and has recommended adding pH Up. There is also an automatic chlorinator on the pool.

Thanks for any help anyone can give me!!