Pea sized black spot

Dadthepoolboy

Well-known member
Jan 12, 2018
61
Frisco TX
Hello Fellow Pool Boys and Girls,

We just finished building our pool about a month ago. Unfortunately, we've developed a pea sized spot with a black center and brownish cloud moving away from the center.

I tried placing a chlorine tab on the spot, for approximately a week, and brushed. However, this did not cause the spot to fade. I have yet to try Vitamin C. Based on what I have read, I believe this may be calcium scaling with dirt trapped underneath.

I did have to raise my CH and added approximately 7-8 lbs of Calcium Chloride. I brushed and circulated the water. I think my mistake was not running my pool cleaner, for a few days, during this process.

I believe, based off what I've read, that I should drop my pH to 6.8-7 and brush. Supposedly, if this is calcium scaling, the stain will fade in a few weeks. My main concern is that we are in the middle of pool season and we want to enjoy our new pool. 6.8-7 seems a bit acidic to swim in. Obviously, my other concern is that a have a brown spot in my brand, new pool that's driving me crazy.

I have also noticed a white calcium buildup under my spillway. Any suggestions as to how to treat these issues are much appreciated. My pool has remained balanced.

Here are my current readings:
pH 7.5
FC 9
0 CC
CH 250
TA 100
60 CYA (Despite my warning, PB recommended using tabs. I was ok with this to raise the CYA. However, once I realized the feeder needed to be turned down, the CYA was a but higher than I would prefer. I am currently using liquid chlorine.)

I need to change my signature as we now have a 12K gallon pool with pebble sheen. Thanks in advance for any guidance.
 

JamesW

TFP Expert
Mar 2, 2011
17,004
 

Dadthepoolboy

Well-known member
Jan 12, 2018
61
Frisco TX
So no magnetic activity. Sorry about not answering that. I thought I had. I called the builders startup guy. Granted it was yesterday, but I haven't heard from him. I haven't mentioned it to the builder because I felt it was my responsibility. However, it may be time to reach out to them.
 

Dadthepoolboy

Well-known member
Jan 12, 2018
61
Frisco TX
Sorry about the delayed response. I've been dealing with a family emergency.

I am not sure about the strength of the magnet. I used a telescoping magnet. The ones that can be used to pick up dropped screws in tight places. The magnet did appear to stick in certain areas of the pool close to the spot. However, it slid right off the spot.

I still have not heard from the PB start-up guy. I will reach out to the foreman.
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