First Test with TF-100 / High CH


Jul 21, 2019
Tampa, FL
My pool was filled 7 days ago and I was given no instruction on maintenance of new plaster. Luckily I found you guys and finally received my TF-100 in the mail. I also downloaded the app to log my results. My pool school is scheduled for the 30th, so my PB is not officially done.

So far I have only added acid for ph maintenance and brush twice daily. My pump is running 24/7, 16 hours on low and 8 hours on high. When should I start decreasing run time?

FC 4
pH 7.5
TA 60
CH 600
CSI -0.12

My CH seems high but not sure if this is from the new plaster. Is this something I need to get a handle on right away? I did notice two small bumps in my plaster, which look like calcium nodules. (Picture attached). Should I bring that up with my PB?

Also, I’m planning on buying some stabilizer this weekend to increase the CYA. Is a range of 30-50 good?

Sorry for all the questions. Thanks for the input!



Gold Supporter
TFP Guide
Jul 21, 2013
Northern NJ
Don’t worry about the CH right now.

The bumps just look like areas they didn’t smooth out the plaster. You can point them out to the PB.

Follow the most suitable startup guide or what your builder gives you...

Let your pH rise towards 7.8. You want your CSI higher in the first 30 days.

Keep your pump running and keep brushing to filter out the plaster dust.


Mod Squad
LifeTime Supporter
Jan 17, 2012
Evans, Georgia
Yes, please put some stabilizer (CYA) in that baby. Take it up to 30ppm.

As to the high calcium- I would imagine you are getting some of the calcium in the test from the dust you're brushing to get into circulation for the filter to pick up. That should decrease in time as you brush.

Keep an eye on your pH which will tend to rise frequently as the plaster cures.

You do not want a largely negative CSI at this point. Most folks aren't following CSI in the early days. From the cement/plaster expert:
Once the pool is filled, balance the water (and keep it balanced). Balanced water helps help preserve the plaster. Aggressive water causes uniform etching, while over-saturated water scales plaster. The Saturation Index is a good guide to prevent scaling or etching, water should have a saturation index value in the range of -0.5 to +0.5.

Maddie :flower:


Gold Supporter
TFP Guide
Jul 21, 2013
Northern NJ
The CSI is not applicable to new plaster finishes under 30 days old. It is actually necessary, to achieve a smooth and dense surface, to have about a +0.5 CSI during the first 30 days. This is because the plaster (cement paste) surface contains about 20% calcium hydroxide, which is somewhat soluble in balanced and slightly positive CSI water and can be dissolved away. The plaster surface needs to be "carbonated" before the CSI should be lowered to the acceptable and balanced range. And that generally is achieved during the first month under balanced water
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