New plaster chemical balance

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J

jeharley

0
Mar 30, 2017
51
Lexington, SC
Hi everyone.

I had my 30 year old gunite pool replastered 2.5 weeks ago. I had some issues in the beginning and spent the last two weeks getting the pH, CYA, and Chlorine established and brushing and backwashing. I felt ready today to do comprehensive testing.

Results:

FC 5.5
CC 0
CH 75
TA 30
PH 7.3
CYA 20

So obviously the TA and CH jump out at me as super low. I can bring those up but just want to make sure that I don't do anything to compromise the new plaster in these early stages.

Should I just go ahead and bring up the TA and CH like I normally would or are there any special considerations with new plaster? What are the ideal levels and approach in this situation?

Anything else that looks concerning in those numbers? I am still bringing the CYA up slowly.

Thanks in advance!
 
Unless your plaster contractor has any other warranty concerns or specific guidelines for you to follow, I would make the following changes:
PH - Has the biggest impact on acidity right now; aerate and increase pH to about 7.7 for now
CH - TFP min 250; at least get it closer to 200 for now; you might see the CH change as you continue to brush
TA - TFP min 70; at least closer to 60; 70 -80 is fine as well

Those ranges, while still slightly under the TFP recommended zones, brings your CSI (Calcite Saturation Index) in a better range (-0.16) for the plaster than it is right now (-1.31). Hope that helps.

- - - Updated - - -

Please see the TFP Pool School - Recommended Pool Chemicals for thoughts on which products will work best to raise each item - some of them together.
 
Thank you so much for the info!

I also spoke to my builder. He told me to hold off on the TA but to go ahead and start bringing that CH up. I bought 35 pounds of increaser from Lowe's which is about how much I think I will need. The directions say to divide the dose in thirds and wait 6 hours between applications which seems a bit tedious and I'm wondering if it's really necessary. I went ahead and put in 5 pounds.

I have noticed some gray, orange, and yellow staining and etching/scratches in my plaster (more gradually appearing over the last week or so) and now I'm super paranoid that it's my fault for waiting two weeks to worry about CH... and then I also worry now that this could be detrimental to the durability and life of my new plaster moving forward? The builder told me initially to just worry about adding MA to keep the PH down and brush and then to gradually add CYA and Chlorine so that's all I worried about until that all got sorted and the water got clear. Is this normal or something worth worrying about?

As far as TA, it seems it's main function is to keep PH in range, but my PH has been very manageable for the last week plus. Is there another reason TA matters?

Sorry for the long anxious post! I just want to avoid spending MORE money on this pool anytime soon! lol
 
Yes, TA's main purpose is as a buffer agent to the pH. It also contributes to the overall plaster (CSI) condition as well. When your plaster was first completed and filled, did the contractor add any sequestrant? That's normally done to prevent staining in case there is iron in the local water. Were you using a steel brush, nylon, or 50/50 on the new stuff?
 
Texas Splash said:
Yes, TA's main purpose is as a buffer agent to the pH. It also contributes to the overall plaster (CSI) condition as well. When your plaster was first completed and filled, did the contractor add any sequestrant? That's normally done to prevent staining in case there is iron in the local water. Were you using a steel brush, nylon, or 50/50 on the new stuff?
Click to expand...

The builder did add a start up dose of sequestrant (I did not see them do it but they showed me the empty bottle- Jack's Pink Stuff I believe).

I have been using the blended brush that was left by the previous owners (Its probably 90/10 Nylon/Steel). The builder actually told me I could go ahead and use full stainless steel brush (one of several curious pieces of advice they have given me) but everything I have read says full nylon brush, maybe switching to blended after a year. I just bought a full nylon today so will be using that moving forward.
 
Texas Splash said:
Later you might want to post an image or two of the effected areas so our plaster experts can take a peak. Perhaps they will see something in the details that can help.
Click to expand...

20180328_153929.jpg

20180328_153943.jpg

20180328_153937.jpg

Those are some of the small gray streaking or scratchy looking marks. They laid a gray cement like under layer before laying the plaster so my first guess was it was just rubbed or scratched off in a few places but I can't say for sure obviously.
 
I have several more photos to share but this forum keeps giving me an error message even after I resized them repeatedly.

Essentially other than the ones you've seen above, there are also some small streaky light rust colored spots. One of the more concerning spots is probably the size of tennis ball and looks like basically a spot with a bunch of concentrated ridges or wrinkles in the plaster. This spot is where the wall meets the floor. In that general vicinity there is also a good bit of light yellow discoloration on the wall and streaks running down and rougher texture but it's not really visible thru photos.
 

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TA is 20 this morning. I'm going to go ahead and add 8 pounds of baking soda and go from there. The CH is now at 200 and I just added another 5 pounds of CH increaser to bring it to 250-300.

The first week of the new plaster I added a lot of MA and it made the PH reading yellow (I was guessing it was like 6) but it came back up to around 6.8 after a few days so I just continued to let it slowly rise by itself over the last couple weeks to about 7.3 now. The builder told me to worry about PH not TA and to just keep the PH around 7.2. I believe this was the start up procedure to help remove the plaster dust n such. In retrospect, I'm thinking now that the blemishes in the plaster are probably associated with the aggressive PH, TA, and CH levels over the last couple weeks. Does this sound right to anyone else?
 
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