Pool Bottom/Marcite.. Very Concerned!!!

[Cayman]

I was doing my normal walk around looking at the pool admiring how nice it was looking. I then noticed that there were some bumps and some areas where it looked like the marcite was going away or being eaten away. I have never noticed this before (except for a few bumps on the steps that have been there since we moved in) so I am not sure if it was the lighting of the morning or if this is something new. I will be able to confirm if they are new tonight when I put the pool light on. I am pretty sure they are new because I am very anal and I pick up on things and this is something I would have saw/remembered. :?

I just took new tests and here are my results...

FC - 19
CC - 0
TC - 19
PH - 7.8
TA - 80
CH - 310
CYA - 70
Salt (SWG) - 3500
Salt (Strips) - 3460
Borates - 30
Temp - 69


I also took some pictures to help diagnose this.

Look at the top right are of this one... looks like it has been scraped away.

 

[Cayman]

I was concerned about this so I decided to take a sample of my water to 2 local pool shops for testing. Here are the results compared to mine. I am confused!!

I guess the biggest one I am concerned about with my current issues would be the wide range of CH. I think I may be testing wrong. When testing am I looking for the color shift or until it is totally blue? Because it actually changes to a light purple first then about 5-7 drops later turns to blue.

MY TESTS
FC - 19
CC - 0
TC - 19
PH - 7.8
TA - 80
CH - 310
CYA - 70
Salt (SWG) - 3500
Salt (Strips) - 3460
Borates - 30
Temp - 69


STORE #1
FC - 5.0+
CC - N/A
TC - 5.0+
PH - 7.6
TA - 85
CH - 250
CYA - 100
Salt - 3100


STORE #2
FC - 5.0+
CC - N/A
TC - 5.0+
PH - 7.4
TA - 80
CH - 190
CYA - 60
Salt - 3420
TDS - 2000
Phosphates - 500

 

[Guest]

CH test reaches endpoint when the color does not change any further when more drops are added so your color change of purple is an intermediate. Remember to swirl for about 30 seconds between drops (or use a magnetic stirrer like the pool stores do if they have the full Taylor lab). I would trust your own test results over the stores as I have come across very few pool store employees that actually know how to test water properly! Did the pool stores stop testing when the water changed to purple or blue? Also were they counting drops or using a burette to dispense the reagent. If the burette is not read properly it will introduce error into the measurement. The two stores had a variance of 60 ppm in their readings and you were 60 ppm above the closest one. If your results are repeatable I would trust them. One experiment you can to is to take 3 samples of the same water to the pool store (have different people bring them in one after the other) and see how close the results are. I think you will be surprised!

I suspect that the variations in your marcite are not new and you have just not noticed them before. I have seem similar imperfections in most plaster pools. It takes a bit of time for plaster finishes to be degraded by improper water chemistry and the type of surface irregularities in your pictures would take at least a season or two to surface unless the water balance was WAY off. Remember that low pH is the largest contributing factor to plaster damage since very small changes in pH will have the greatest impact on saturation index.

I suspect that at least some of the imperfections you are seeing go back to the curing stage of your plaster. New plaster is easy to damage since the surface is still soft.

 

[Cayman]

Pool Store #1 used a burette and Pool Store #2 stopped at purple and not blue. That is why I asked the question about that originally.

The pool was built on May 2006 so it is a little over 2 years old. Not sure if that helps or not.

I was just worried that these nipples were just starting to pop out because of something that I have done. It is weird!!!

Maybe my water is so clear now from help on this site that I am just now seeing all of the imperfections. LOL :-D

 

[Guest]

I was just worried that these nipples were just starting to pop out because of something that I have done. It is weird!!!

Perhaps this will help.
http://www.poolhelp.com/onBalanceCalciu ... lletin.pdf

 

[Cayman]

Good article... Thank you.

It appears that when it is done, that they can possible be removed. Interesting and could be good news I guess.