Calcium Hardness went way up!

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Good afternoon, I have been struggling with chlorine output since January. Since coming to TFP I have been able to solve my chlorine problem but recently my CH as gone wild. About a month ago my CH was about 250, now it is about 900. What could have caused this?

FC 3.0
TC 3.0
CC 0.0
PH 7.8
TA 70
CH 900
CYA 60
TEMP 75
 
My first reaction is an error in your test procedure. CH is one of those fixed things that does not dissapate, reduce, or increase unless you add it.

Using Cal Hypo as a chlorine source will bump your CH but nowhere near that much in the time frame you are talking about.

I would think a testing error is the only plausible explanation.
 
Dave,

Actually, I tested it three times today (In the rain). Once with the kit you just sent me and the other with my taylor kit. both readings were similar. It took about 90 drops before the red turned to a purple / blue shade. Since I am a newbie, what is Cal Hypo? I have a SWG, but have used chlorine (10%) from home depot to shock the pool. My original problem was that even though I had a CYA of about 70 my chlorine was being eaten up by something. The SWG was at 85% for 8 hours a day and would not keep up in winter / spring months. All my readings seem to be within spec and still I was having the problem. So after reading some posts here I shock my pool for about three days and that problem has gone. Any other ideas about CH? Would rain within the last 24 hours effect my readings?

Thanks
 
Salp,

Well, that's very troubling. to get that type of increase in 30 days, someone would have to put 170 lbs of calcium chloride in your pool.

Cal Hypo is a granulated form of chlorine that is about 1/3 calcium....that means you would've put 500 lbs of Cal Hypo in your pool which you obviously didn't because you don't know what it is.

If it really is that high, you're gonna' need to drain and refill a part of your water....several times.

What is the CH of the water you would refill with?

A very puzzling situation that I wish I could provide an answer to. If we don't get the answer as to why. At least, we know how to fix it.
 
Pool is about 2.5 years old. I have had it tested at leslie's pool in the past and have also confirmed with my Taylor kit one month ago. The only pool products added was chlorine and muriatic acid to lower PH. I will check it again tomorrow. Water does look very clear. I will also check tap water for calcium hardness. Here is one thought, I do have an autofill and if by chance the tap water has changed since I filled the pool?
 
Has it been hot and dry around there recently? A high evaporation rate combined with fill water that is reasonably high in CH could result in rapidly rising CH levels. Calcium doesn't evaporate, so the calcium in your fill water accumulates in the water. But you would need to have a rather high evaporation rate to get up to 900.
 
Here is one thought, I do have an autofill and if by chance the tap water has changed since I filled the pool?
Click to expand...
No. If you do that math (and I'm too lazy) the fill water would have to be probably 50,000ppm to have that much affect that fast. I'm stumped but I'd sure make plans to get it out of there.
 
I checked tap water tonight and its about 270-280. Waterbear, I am always fighting to keep my PH below 7.6. I am adding at least a 1/2 - 1 gallon or muriatic acid every week to keep PH around 7.6-7.8 I will check pool again tomorrow. PH has never been below 7.2
 

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Good Morning all, I checked water again this morning and this is what's going on.

FC 3.0
TC 3.0
CC 0.0
TA 70
PH 7.8 Adding acid today
CH 750
CYA 60
TEMP 76

As you can see for some reason now its dropped from 900 to 750. Now I am really lost. Maybe calcium aliens are living under the house.
 
I can offer no explanation for the sudden increase or decrease.

Sounds like you need to drain about 1/3 at least twice to get it to manageable levels. No other solution. I hope it doesn't go back up after you do.
 
Dave,

That looks like my only choice. I did go to Leslie's and they checked it twice for me. The outcome was better but still on the high side of good. Both times they were at 400ppm. So, I feel a little better but still stunned at why it rose from 250ppm a month ago. I will probably drain about a third of the water and refill. Besides the high CH everything else looks great including pool. All the other readings at Leslie's concurred with my earlier testing. My CSI is -0.05, which is balanced. Is it possible that I added to much muriatic acid at one time and it cleaned the build up and added calcium to the pool?

Thanks

Sal
 
Your area (like mine -- I'm just down the road from you) has an evaporation rate of about 70 inches a year. That's all of the water in the pool in 1 to 2 years (depending on depth) In 2.5 years it is possible to have the water replaced twice. Theoretically -- with no splashout -- this could get the water up in the high 800s. But that doesn't explain the test a month ago.

How close were you to the fires last November -- could that have anything to do with it? A friend had half the water evaporated from his pool from the heat of the fire. Again -- not in the last month -- just brainstorming....

Steve
 
Thanks for the feedback, I was planning on changing 1/3 of the water at 3 years anyways, I will do it this week and see what results I get. Thanks for all the help! Other than high CH life is great! GO TFP!

Sal
 
Good morning all, I changed about 8,000 gallons of water on Tuesday and here are my new readings. The CH has dropped but still abit high. I have ordered a magnetic stirrer to see if I can get more accurate readings. I tested CH at about 450, I had Leslie's test a sample and they read 300.

FC - 2.0 (I am super chlorinating as we speak)
TC - 2.0
CC - 0.0
PH - 7.8
TA - 80
CH - 450
CYA - 50
Temp - 79
Salt - 3000

Is stirring that important? It must be because there readings are always lower on CH.

Thanks

Sal
 
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