Calcium Hardness Fiberglass Saltwater Pool

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M

mavitia22

Well-known member
Jun 27, 2023
61
La Vernia, Tx
Pool Size
16000
Surface
Fiberglass
Chlorine
Salt Water Generator
New pool owner. (2 months)

Started noticing concrete bullnose edges were turning white and chipping off a little. So, I started reading on LSI and water balance. Pool guy and pool store don't seem too concerned (or dont care) about LSI, but I am now because I'm pretty sure my water was corrosive due to low calcium.
Raised calcium to 120 because that's pool manufacturer recommendation. But based on that level, consi20230620_124557.jpgstently having high PH (7.8-8.0) due to saltwater, and high temp (84°), adding muriatic acid to lower my ph will make my water corrosive. They keep telling me to lower my ph because fiberglass recommendations are 7.2 -7.6, but that just wouldn't work with my water readings.
FC - 2.5
TA - 90
PH - 7.9
CH - 120
Salt - 2400
CYA - 36
My concern is...which is worse? Low calcium or high PH? I can't seem to keep ph low cuz of the saltwater. It goes right back up day after adding acid, and I'm not sure I want to add acid everyday. Plus, it lowers my alkalinity. How do I keep ph stable and within 7.2 - 7.6 range? Seems impossible with the saltwater. Will adding calcium affect the fiberglass? Will high ph affect the fiberglass? So much info and opinions have me overwhelmed.
I just don't want any more damage to my new concrete, which I need to have sealed anyway. I've included a picture.
Any help from a fiberglass saltwater pool owner would help. Thank you.
 
To address some of your concerns. As long as your pH is between 7.2-7.8 your are usually good. This time of year, the pH likes to be around 7.7-7.8. That's okay. Let the TA fall a bit more closer to 60 and that should help keep the pH from rising too fast. As for CH, as long as you don't have a really old FG pool, waterline tile, or a heater that specifies a minimum CH, a CH of 120 is plenty. The lower the better to reduce scale in your SWG.

Watch your salt level so it doesn't get too low. We recommend a CYA of 70 to protect the FC from the hot sun. Always keep the FC balanced to that CYA as noted on the FC/CYA Levels. Hope that helps.
 
Texas Splash said:
To address some of your concerns. As long as your pH is between 7.2-7.8 your are usually good. This time of year, the pH likes to be around 7.7-7.8. That's okay. Let the TA fall a bit more closer to 60 and that should help keep the pH from rising too fast. As for CH, as long as you don't have a really old FG pool, waterline tile, or a heater that specifies a minimum CH, a CH of 120 is plenty. The lower the better to reduce scale in your SWG.

Watch your salt level so it doesn't get too low. We recommend a CYA of 70 to protect the FC from the hot sun. Always keep the FC balanced to that CYA as noted on the FC/CYA Levels. Hope that helps.
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Ok, yes, that helps. Thank you.
 
RookiePick said:
I can't see any way the water in the pool could have made your concrete coping develop the split you are showing(?) in 2 months due to any corrosive properties.

I'm in the same boat with a new FG pool and the CSI number in poolmath is scary to look at.
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I know. It looks so bad , being that it's brand new. It's been overly stressful. I can only attribute it to the LSI because looking back at my printed reports, it was always below -0.3. I just didn't know what it was until I started reading about it. I'm sure the saltwater factor doesn't help.
 
Pushing your pH lower will only make the CSI number head further into the negative. Whether that is relevant to anything to do with your pool surface, equipment or surrounds I'm not sure.

Have you spoken to the PB or whoever did the coping?
 
RookiePick said:
Pushing your pH lower will only make the CSI number head further into the negative. Whether that is relevant to anything to do with your pool surface, equipment or surrounds I'm not sure.

Have you spoken to the PB or whoever did the coping?
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I guess I'm going to give them a call. Not sure they'll care..lol..but I'll give it a try. Thank you.
 

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Texas Splash said:
Okay, so that is actually plaster in the top half of the photo you posted. Does the waterline typically stay below the plaster at the gelcoat level, or does the water actually go up that plaster surface a bit?
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Yes, that's concrete edge. No, the waterline usually stays about 4 or 5 inches below. I'm gonna call a concrete guy for his opinion.
 
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mavitia22 said:
No, the waterline usually stays about 4 or 5 inches below. I'm gonna call a concrete guy for his opinion.
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In that case we can rule-out any link to the pool chemistry since you were worried about a low CSI earlier. It looks more like a bad application to me, but let's see what your pool folks have to say about it.
 
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