What are the dangers of low CH?

[Guest]

I've finally determined that my CH is really low.. Around 150-175.

Previously, I had trouble getting an accurate test due to metals in the water, but that problem seems to have dissappeared and last night I was able to do an accurate CH test

My pool is fiberglass and the rest of my numbers look good, except for PH is a little low.
I've heard that getting the Calcium hardness up a little could help with stain problems - is that true?

 

[MikeInTN]

Copied from Pool School :

CH - Calcium Hardness

Calcium hardness indicates the amount of calcium in the water. Over time, water with low calcium levels will tend to dissolve calcium out of plaster, pebble, tile, stone, concrete, and to some extent fiberglass surfaces. You can prevent this from happening by keeping the water saturated with calcium. In a vinyl lined pool there is no need for calcium, though high levels can still cause problems. A plaster pool should have CH levels between 250 and 350 if possible. Calcium helps fiberglass pools resist staining and cobalt spotting. If you have a spa you might want to keep CH at at least 100 to 150 to reduce foaming. CH contributes to the CSI which indicates the tendency for paster damage or calcium scaling.

You increase CH with calcium chloride, sold as a deicer and by pool stores, or calcium chloride dihydrate, sold by pools stores for increasing calcium. You lower calcium by replacing water.

 

[ckf]

You increase CH with calcium chloride, sold as a deicer and by pool stores, or calcium chloride dihydrate, sold by pools stores for increasing calcium. You lower calcium by replacing water.

Since one chemical seems to always cause another measurement to change . . . do I have to worry about calcium chloride or calclium chloride dihydrate changing any other readings other than the CH? I am only trying to get our CH from 230 to between 250 and 350 as recommended and we finally have most of our measurements pretty close to what they should be - I just don't want to rock the boat.
Thanks.

 

[JasonLion]

Calcium won't change any of the other levels in any significant way.

 

[Guest]

I should mention that my CH was extremely low when I opened the pool this summer. Under 100ppm.
I don't believe I was ever checking it properly all of last summer.

It's been somewhat difficult getting it into my target range of around 250-300.. It's around 230 now and I'm actually chlorinating a bit with Cal-Hypo to help. So far, it does seem to be helping keep the stains at bay.