Does a heat pump alter water chemistry?

[Zaphod]

I'm installing a heat pump for my 30,000 gallon IG pool. It's 80 to 90 percent in the shade, so while the air temp may be 95 degrees the water is 74 F - a little cool for my Southern blood. I'm shooting for 80 degrees with the heat pump.

My question is this: Will the heater alter my water chemistry? Will I need to balance any differently?

My current numbers are:

FC - 6
CC - 0
TC - 0
Alk - 100
Ph - 7.5
CYA <20 ppm (aiming for 20-30 ppm)
Temp - 74

I'm on the BBB schedule, though I'm running some tri-chloro pucks in my feeder to get some stabilizer into the water.

Any thoughts?

Thanks,

Zaphod

[waterbear]

not really, but if it has a copper heat exchanger you want to keep tabs on pH, TA, and calcium (you will need calcium with a heater, you didn't post any calcium numbers). titanium heat exchangers are a bit more resistant to corrosion but scaling is still a problem.

[Zaphod]

Waterbear,

My pool has a vinyl liner, so I haven't been testing for calcium. How does a heater change the need for calcium? Is it a scaling issue? I have read items suggesting that calcium is needed for pool plumbing, but I didn't understand the rationale.

If that's the case, what should be my target calcium number in ppm?

The heat pump I've selected has a titanium heat exchanger (the unit is by Jandy).

Does any of that change the equation or advice?

I appreciate your comments.


Zaphod

[waterbear]

Waterbear,

My pool has a vinyl liner, so I haven't been testing for calcium. How does a heater change the need for calcium? Is it a scaling issue? I have read items suggesting that calcium is needed for pool plumbing, but I didn't understand the rationale.

If that's the case, what should be my target calcium number in ppm?

The heat pump I've selected has a titanium heat exchanger (the unit is by Jandy).
Titanium is not prone to corrosion like copper is but scaling is a problem in either one. If your calcium is high and your TA is high then it can become a problem.
Does any of that change the equation or advice?
No, pH is the factor that seems to have the greatest effect on whether the water is corrosive or scaling but it is also influenced by the CH and TA and temp.
I appreciate your comments.


Zaphod

It is generally accepted that calcium is not an issue in vinyl or fiberglass pools unless you have grouted tilework or a heater. Then it is ususally treated similar to a plaster pool for water balance. I am not an expert on this. Perhaps someone else will chime in?

[Zaphod]

I finally tested for calcium. The reading is 20.

All my other water numbers are the same.

The heater will be installed next week. Any tips for what my target calcium number should be? If I need to increase, what do I add - and where do I get it? Is it a pool store chemical or is there a grocery store substitute?

[waterbear]

You can buy calcium increaser in the poolstore but if you can find DowFlake brand de-icer at a hardware store it is the same thing. If you go to the Dow Chemical website they list is as the product for increasing calcium in pools! I posted the url in a different thread but am not sure where in the foum it is buried now. The DowFlake is substantially cheaper than what you will pay at a pool store or even Walmart! Might be hard to find during summer, however.
I suspect that since Dow is one of the largest manufacturers of calcium chloride that most, if not all, of the calcium increasers sold for pools is just repackaged DowFlake! Bring your calcium up to about 150-250 ppm and run your TA at about 110-125 and you should be fine. (adjust TA first, test it after 48 hours and then adjust calcium)