What is hardness?

[jerome]

what role does "hardness" play in the overall balancing of a pool?

[PoolDoc]

Hardness is just a measure of how much calcium is in the water.

It has to be managed closely on concrete pools, to avoid dissolving the plaster. On pools with heaters and SWCG's, the primary concern is to keep it from getting too high, lest scale form.

[jerome]

My water hardness tested 30, very low. Does it have an affect on balancing the the other chemicals? In what order should it be addressed?

[PoolDoc]

Hi Jerome;

To answer your question, just a bit pointedly: "Yes", and "In the correct order, which depends on other things". And, to answer the questions you didn't ask, "Is a hardness level of 30 ppm a problem?", AND, "Is testing by pool stores, or by test strips reliable?", to which the answers are "Yes, or no, or maybe -- again depending on your situation" AND "No, they are not reliable".

Do you have a pool you're trying to care for, or are these just general purpose questions?

If you have a pool, then hardness is not where you begin. More importantly, it makes no sense to talk about hardness out of context. So, if you've got a pool, tell us about the pool, and why you're concerned.

On the other hand, if you are just asking general purpose questions, this is not the time of year for us to be doing that. We're pretty much buried, trying to help people get pools going. I would suggest you check out "water hardness" on Wikipedia, and look through some of the pages on PoolSolutions (linked in my signature).

Best wishes,

[jerome]

Yes I have a pool that I am about to open! IT's 50,000 gallons, cement Wagner pool, in Connecticut. Does that give you enough background information?

[CarlD]

Yes I have a pool that I am about to open! IT's 50,000 gallons, cement Wagner pool, in Connecticut. Does that give you enough background information?

We try to help a lot of people here. No need to get snippy.
Ben's answer was perfectly logical. If you have a vinyl pool, a level of 30 ppm for calcium hardness is fine. Vinyl is unaffected by hardness. However, for a concrete, plaster, tile or other masonry pool, calcium levels are critical with the suggested range being 200-400 ppm. Lower levels can cause the calcium carbonate in the concrete/plaster to leech out, weakening it.
We view store testing as a second or third best solution generally. Different stores and even staff can make a difference.
Our view and opinion and recommendation is to use the Taylor K2006 test kit for your pool. Alternatively, Leslies FAS-DPD service test kit is virtually the same thing. We like the idea of one person doing the testing so that changes aren't due to a change in tester.