How much Calcium do I need?

[grdnchik]

I think our pool needs calcium. We have pebble tec and it is becoming a bit white in certain areas could it be that we need calcium, and it is drawing it from the gunite? Our pool is about 15,100 gallons and my cal is reading at
120. I read other post on how to raise it with some deicer product, but is there a calculator or some other way of finding out how much to add? Thanks a bunch in advance.

Elsa

[chem geek]

Please post your other numbers, especially pH, TA and CYA (temperature would also be nice) and if you are using Borates (Borax) in your pool at high levels (e.g. 50 ppm as opposed to just using Borax to occassionally raise pH).

I doubt that you are out of balance with water chemistry enough to cause corrosion, unless your pH and/or TA are quite low. I'll also need to know if the calcium you are buying is anhydrous calcium chloride or dihydrate calcium chloride (it should say on the container). You can usually just use the guidelines given on the container that will often say "add xx pounds per 10,000 gallons to raise calcium hardness by xx ppm" or something like that.

Richard

[CarlD]

You can always start chlorinating with Cal-Hypo until you reach your target.

Don't use the 48% garbage, though--use the 62-68% stuff.

Get the smaller amount so you DON'T buy too much. (sorry--typo that I fixed--C.) The increase in calcium will be gradual but definite.

HTH stuff sold at WalMart and other discount houses is usually 48%. There's another label that I can't ever remember that's 62-68%, and sometimes there's private label cal-hypo at that concentration. Both HTH and the other label are Arch products, but at least the with the other you're not buying 52% of nothing.

Do NOT put cal-hypo in an automatic chlorinator. If you get the cal-hypo tablets you can put them in your skimmer or a NEW floater. Do not pour bleach over cal-hypo.

[chem geek]

Carl's idea is a great one (wish I'd thought of it!). If you were to add one pound of 65% Cal-Hypo to your 15,100 gallon pool, it would increase the Free Chlorine (FC) by 5.1 ppm and would also increase the Calcium Hardness (CH) by 3.6 ppm. Though it won't get your calcium up quickly at least it's in the right direction and it does give you the option of another chlorine source -- one that is sometimes less expensive than liquid chlorine.

Richard

[CarlD]

I'm always a big fan of: If you don't know if you should add more, or less of any chemical, add less--except for chlorine--add more.

But powdered chlorines are not just chlorine, so I like the "go slow" idea.

The whole point is if you put too much of just about anything in your pool you have to now do something else to fix it. If you put in too little, you add more.

Except for bleach. Too little you get algae (BIG bad!), too much you may bleach your liner (little bad), if you have a liner.