Calcium Hardness

[Ciscokid]

What is your CH of your fill water? You mentioned that you refilled and your CH was 200 which indicates that is all from the fill water. That is fairly high and will build up over time. I have the same problem. When water evaporates it leaves the calcium behind and since the fill water has a fairly high CH, you are continually adding calcium.

If this is true that would explain exactly what is going on with my CH.I will measure the CH of my Fill water tonight and double check. I am not to far from you. I live in Manteca, CA. So I would expect the fill water to be similar.

[chem geek]

To get from 200 CH with fill water to 550 CH after evaporation and fill, it would take 550/200-1 = 175% of your pool water volume to achieve that. That's an awful lot of evaporation, but perhaps is what is happening in your case. If you have a bucket of water next to your pool, you can see how quickly the water evaporates. Assuming a 4.5 foot average depth for your pool, you would need evaporation of 4.5 * 1.75 = 7.9 feet of evaporation per year or 0.26" per day (actually double that or around 0.5" per day since there isn't much evaporation in the colder months).

Richard

[mas985]

95" is less than what parts of Arizona and Texas experiences over the year so it really depends on where you live. Check out this Link for where you live to get an estimate.

I experience about 60" with is a full pool volume over the year so my CH almost doubles over the year.

EDIT: I should modify this some by saying that with a pool cover, you can greatly reduce the amount of water lost and thus the buildup of calcium.

[chem geek]

What a great link! I've bookmarked that one! Thanks.

[waterbear]

95" is less than what parts of Arizona and Texas experiences over the year so it really depends on where you live. Check out this Link for where you live to get an estimate.

WOW according to this my pool will lose it's full volume plus about 1 third more over a years time and my hot tub over 3 times it's volume!

[salinda]

WOW according to this my pool will lose it's full volume plus about 1 third more over a years time and my hot tub over 3 times it's volume!

Hey Waterbear...I live in Northern California and evaporation is always a problem. I am wondering if you use a cover at all. I use those silly solar fish and they do seem to mitigate the evaporation quite a bit.

Jumping in here, my calcium is also high at 520-530. It is actually hard for me to get it to blue with the kit because the water in the tube starts globbing up as I add more reagent. I recently successfully lowered my alk from 130 to 90. My ph is hanging out in the mid 7's right now for much longer than it ever has. I have had high calcium for years now and my plaster is very smooth. I do get flakes from the returns sometimes, but the cleaner sucks those into the filter, except in the spa where I use the PoolBuster to remove them. It actually seems like there are fewer flakes this year than in previous years...

I am keeping an eye on everyone's borate experiences as well, but things look good now so I don't want to mess with the water chemistry too much.

[chem geek]

Salinda,

When you had CH of 525, TA of 130, and the pH was rising and hit 7.7, then your saturation index was around +0.6 so slight scaling was possible. With your current TA of 90 and a pH of 7.5, your saturation index is a much more manageable +0.21.

If you use a non-acidic source of chlorine such as chlorinating liquid or bleach, you can lower your TA even more if you want to, even to 50 ppm, and this should further reduce the tendency of your pool's pH to rise. You'll probably find that something like 70 ppm will be fine.

Think of this as an advantage to having a higher CH pool -- you can have a correspondingly lower TA and have calcium carbonate saturation in balance and be even better off in terms of having less pH rise.

Richard

[salinda]

Richard,

Thank you so much! It was your previous comments on the feasibility of low TA with high CH water that gave me the courage to try to fool with the chemistry. I'm glad I did! I test my water myself, but so does the pool store when I go for a visit. This is a local store that maintains pools on their service with liquid chlorine. They completely concurred and understood Ben's method for lowering TA. It sounds like they use this method too. I am steering friends who are looking for a good pool store to this one from now on! The owner was a little concerned about the TDS of the water, but the CH has changed so little in the 3 years I have owned the pool that I am not really concerned.

I use an swg for chlorine. Are you proposing that I turn that off and switch to bleach? I could probably repeat the lower ph/aerating method and get the TA down even further. If I do the adjustment for stabilizer that others do, I am already there.

Maybe we should move this to a new thread....

[ndillon2]

Cisco,
Does your salt cell clog with scale build up? I have the same issues with CH and PH rising quickly. I go through 2-5 gallons of acid per week just to keep the PH down around 7.2-7.5. The SWG cell clogs with scale every day. I have to remove and clean with a power washer. MY Ch is also 600+ and there are scale flakes that come out of the return lines into the pool. I have considered bypasing the SWG as it is more problem than normal maitenance. However, I just feel like I am missing something and should not give up on it. Any help is appreciated. Thanks

[Ciscokid]

ndillion2,
I don't have a problem with scaling on the Cell.( other than the normal build up.) I clean it maybe once a month or so. Other than my CH being 550 all other chemicals are perfect. The pool itself is crystal clear.
Post all your chemical readings and maybe someone can better help with your problem.
Based on all the help I am going to raise my borates to see if it will slow my PH rise.Also I may airate the pool and get the TA down to 80. Thank you all for you information .