Help! My Ca is Out of Control

[mphare]

My pool is:
13,500 gal gunite
basic White Plaster
1/2 coping is flagstone
1/2 coping is moss rock (like the waterfall)
Aquarite Salt System
2~3 foot waterfall
Bubbler on Tanning Ledge

My current chemistry is (using a Taylor 2005):
Water Temp: 84-ish (F)
pH: 7.6
Alk: 110
Cyanuric Acid: 70-ish
Total Cl: 10
Free Cl: 10
NaCl: 2900

Ca Hardness is 625
(the Ca of the fill water is 250)
I keep a history of my pool chemistry and according to the spreadsheet, my Ca was at 500 in April

I control my pH/Alk with about 1 ~ 2 qts of Muriatic dropped once a week to bring the pH down to 7.2. I aerate about 10 hours a day, every day (whenever the pool is on, so is the waterfall and bubbler, and it's on about 10 hours a day).

So,

Is 625 a 'bad' Ca Hardness level?
My worry is it will continue to raise and me at 800 by the end of summer.

Why does Ca levels raise?

[CarlD]

What are you chlorinating with? If it's Cal-Hypo, that's your problem.

Otherwise, I suspect it's in the plaster, and the rocks and morter.

You may want to drain about 3/4 of your water and refill--try and find a water that's not so full of calcium...I don't know if a water softener will help.

[mphare]

I have an Aquarite.

I don't have much choice for filling the pool. What comes out of the tap is what I have to work with.

The pool is in it's third season, and the rest of the chemistry is fairly stable.

Why would I still be leeching?

Thanks!

[mas985]

Mike,

Have you tested your fill water lately? I would check it before assuming it is from the plaster. If it is your fill water, a softner is about your only choice short of trucking in water.

[duraleigh]

The only thing I'd add is 625 looks like a pool store test. Regardless of who's test it is, I would verify those results before planning a course of action.

[cwstnsko]

Are you have some sort of problem with water clarity? 600 ish is pretty common for CH here in AZ. Most people don't run into any trouble until 900 or 1000. Fill water is about 250 here as well. You accumulate CH because it is in your fill water, but does not evaporate. I tend to keep my Alk a little closer to 80 when the Calcium is high. Other than that, I just enjoy my pool :) I've been trying to keep track of the CH level of the fill water on a seasonal basis. If I can find a season where the water has less calcium, I'll probably just plan for a yearly partial water change timed to the lowest CH levels of the year.
My pool is 2 years old, never had a water change, started at CH of about 400 with new pebble-sheen. It has crept up to about 600 in 2 years time. As stated above, stay clear of the cal-hypo.

[mphare]

No. In fact I believe the water is quite clear. I don't perceive any issues, I just want to be sure there isn't a problem with the CH that high.

I test using a Taylor 2005. Granted, this is my first year to test with the Taylor, so I may be off on my readings.

When I had the pool store test the water, they get a lower CH level. I believe it's because they stop dropping reagent as soon as the water turns purple (away from red), not until it stops changing color and into blue.

Thanks!