New plaster CH question

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G

gmgm55

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LifeTime Supporter
Jun 28, 2012
45
N. Houston
New pebble sheen pool was filled 9/14 and current test results are:
FC 5.5
CC 0
PH 7.6
TA 120
CH 60
CYA 40

I have read pool school and purchased a TF100.

PB started the pool according to pebble tech's recommendation for the first week. He also put chlorine tabs in which brought CYA to 40 within a week. I figured this was a good value so I started dosing with bleach.

My question is CH; PB told me to not mess with it for the first month. Is this recommended? What is the recommended product and procedure to bring it up?

Any other recommendations are appreciated.
 
Tell the PB that 60 ppm CH is well below the minimum requirement for cement based surfaces as established by the APSP.
Mention that aggressive water dissolves the cement portion of your pool surface material. Put him on notice.
Maybe he will allow the CH to be bumped up somewhat.
 
Here is what I found in pool school:

Calcium hardness can be raised with calcium chloride or calcium chloride dihydrate. They are available in some areas as Peladow, Dowflake, Tetra Flake, or Tetra 94, often sold as a deicer by hardware stores, and some big box stores, in colder climates. Pool stores will carry either calcium chloride or calcium chloride dihydrate under a variety of names, including Hardness Plus, Balance Pak 300, Calcium Hardness Increaser, etc. Calcium products should be spread across the surface of the deep end of the pool.

Shop around and see what is your best price. Any of these products should be fine to raise the CH in new plaster. A slower method would be to use CalHypo for the chlorine source, but that might be too slow of a process for you at the moment.
 
onBalance said:
Tell the PB that 60 ppm CH is well below the minimum requirement for cement based surfaces as established by the APSP.
Mention that aggressive water dissolves the cement portion of your pool surface material. Put him on notice.
Maybe he will allow the CH to be bumped up somewhat.
Click to expand...

I would take the above advice seriously. onbalance knows his stuff. :goodjob:
 
I talked to the PB and he stated the concern was that they expect CH to go up as the plaster cures. He did say that if I wanted to bring it up to go ahead. He warned me that it could go too high as the plaster cures.

Does this sound right? I was thinking of maybe raising to 150 for now.
 
PB could be right but I believe (guessing) that it won't come up high enough on it's own to get you around 250- 400 or so (normal)

I think it would be to your advantage to bring it to at least 200 and monitor it over the next 30 days.

What is the CH of your fill water?
 
The calcium level does not rise (due to the plaster curing) after the pool plaster is one or two weeks old. After two weeks, the only way and the only reason that the calcium levels rises is by aggressive water (which your pool water is) dissolving the calcium from off the plaster surface.
Yes, you should raise the calcium level to about 200 ppm. My guess is that the calcium level is already higher than the original test of 60 ppm. So double check the CH before adding the calcium chloride. And just a word of caution, make sure that the pH is below 7.8 before adding the calcium chloride.
 
My fill water CH is 40 and it went to 60 within the first week and hasn't moved. I will go to the dreaded pool store today and buy some hardness plus to bring the level to 200.

I appreciate all the valuable responses.
 

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Yes.
When the pH is 8.3 or higher, a significant amount of carbonates becomes present in the water. Then when calcium chloride is added, the calcium will combine with the carbonates to produce calcium carbonate, which we all know as scale.
Calcium carbonate is non-soluble, and therefore, forms a precipitate which "clouds up" the water. If not removed by the filter soon, the calcium precipitate can begin to adhere to the walls and floor of the pool, and of course the filter itself can become clogged with scale.

Interestingly, when and after the above occurs, a water analysis test of the calcium content will show no increase. That is because all of the added calcium (from calcium chloride) will have precipitated and then either got filtered out or is on the walls of the pool. Whoever added the calcium chloride will wonder why the calcium level did not increase after adding that chemical. LOL!

Of course, in time, when the pH is lowered to 7.5, it is possible that a lot of the calcium precipitate (or scale) will then re-dissolve and then increase the calcium content. Then a calcium test would show the increase in calcium at that time.
 
duraleigh said:
make sure that the pH is below 7.8 before adding the calcium chloride
Click to expand...
Hope I am not hijacking here. Is that to prevent calcium clouding?
Click to expand...
I cannot see for the life of me why this would be hijacking. You asked a question that fit perfectly within the confines of the subject matter. I firmly believe things like this add to the discussion and help all us learn more. I really think I appreciate the need to keep threads from going off course too far, but I believe we are overly cautious on this quite a lot sometimes. I learned something from you asking the question and onbalance confirming your suspicion. My knee jerk answer was scale prevention...mostly because of my background. I live with scale paranoia on a daily basis so it's kind of ingrained at this point.

I'm not certain of where the line is, but I feel like we should have more flexibility in this regard.

Funny enough, this is on my list of topics I've been wanting to discuss with you. :cheers:
 
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