CSI and scaling question

[Young’s Pool]

Hi I’m new to this and this is my first pool ,I’ve been following the pool math and my pool has been looking
awsome.
FC 3.5
PH 7.5
TA 70
CA 175
CYA 40
I’m trying to understand the CSI, mine says it is -0.55, from my understanding according to Pool Math calcium should be between 250 and 350, My tap water calcium is only 50 ppm so I had brought it up to 175. But I also read if you have a spa to keep calcium lower. But I don’t think my CSI is correct, my alkalinity was at 110 out of tap, was dealing with a bit of a high pH in the beginning so I have been adding acid according to the pool math, now I am at the lowest end of 70 Alk, was trying to keep pH close to 7.5 because I was getting a Little bit of white scaling on my one by one tiles just on the spillway.
Should my pH stay stable now or will I have to continue to add acid ?but then I’m worried about alkalinity dropping too low.
How do I minimize the scale buildup because I don’t think my CSI is right ?
Just trying to get everything on point thanks for any help you may have��

 

[mknauss]

Welcome to the forum!

Can you tell us how you obtained your test results? That is really low CH water for your area. Just want to be sure the results are correct.

With a negative CSI it is virtually impossible to get scale. Can you post a picture of what you are seeing?

 

[JamesW]

What was the highest that your ph went to?

What is the calcium reading right out of the tap?

Do you use a house water softener for pool fill?

How old is the plaster?

 

[Young’s Pool]

I used the TF100 test kit.

- - - Updated - - -

I use the TF100 test kit

- - - Updated - - -

Highest Ph 8.1
calcium reading from tap is 50
no hose water softener
the pool is stonescapes minipebble 1 month old

 

[Young’s Pool]

 

[JamesW]

That looks like efflorescence, which is calcium carbonate from water bleeding through the grout from the other side.

The calcium is from the cement in the wall and grout and not related to water chemistry.

To help improve your CSI, I would recommend that the pH be kept closer to 7.8.

 

[jblizzle]

I agree with JamesW, a higher ph will help neutralize your CSI, but that will not fix your tile issue which is due to water getting behind the tile.

 

[Young’s Pool]

Ok thank you so much. So should that not be doing that? My pool is a new build should I inform my builder? What can I use to clean it off? Also is my Calcium ok at 175 ppm being that I have a spa or should I bring that up higher?

 

[JamesW]

The efflorescence is from water bleeding through the wall.

Is the spa on the other side of the wall?

Is it a spillover spa?

You can raise the calcium level a bit. See recommended levels in pool school. Try to keep the CSI at about -0.3 to 0.0. Put your numbers in poolmath to calculate the CSI.

Temperature affects the CSI, so if you have two bodies of water at different temperatures, you have to find the best balance. Check the CSI at both temperatures and try to find the best fit.

I would make the builder aware of the bleed through issue. It's basically a leak in the spa.

Over time, the leak will loosen the tile and cause the mortar to dissolve and the tile will come loose.

Do you have a picture of the whole pool and spa?