Splotches/discoloration in newish Pebble Tec?

[Rootyb]

So, we had our pebble tec done at the end of May. Since then, it's been fantastic. We had a great summer and probably swam more this summer than the last two years combined.

Within the last month or so, though, I've noticed some discoloration in one part of the pool near the shallow end. Here are some pictures, but I'm not sure how helpful they'll be: Discoloration pics

Any thoughts? I've struggled some with keeping the pH down, but I'm getting it down to 7.6ish every weekend. I was using dry acid at first, but am now using muriatic (diluting in a bucket, adding to deep end with the pump going, then brushing the sides afterwards).

TA is ~60-70, calcium hardness is... I don't actually recall, but it was in the range specified by pool calculator a month or so ago.

 

[YippeeSkippy]

We need a full set of current test results (FC, CC, pH, CH, TA, CYA) as well as knowing what you do to care for your pool and what chemicals you've added.

How do you chlorinate?

Are you using one of the only two test kits we find to be reliable?

How often do you brush?

 

[Rootyb]

So, they did balancing for the first month. I'm not sure what they put in then. I'm assuming calcium carbonate, baking soda, etc. CYA, too, I'm sure. They had a floaty with tricolor in there for a month.

I just added some muriatic acid to get the pH down (from almost 8) and a gallon of 12% chlorine to get the FC up (it was at like, 1). I can go test, but I'm not sure how mixed it is. It's been a couple of hours.

All that I have ever added to the pool is dry acid, muriatic acid, baking soda, liquid chlorine, and tabs for a couple of weeks after they stopped coming.

And yes, I'm using a Taylor (right?) test kit. I'll go do a full test now.

 

[Rootyb]

Okay:

FC: 5ppm
CC: totally forgot, and am just about out of reagent. Need to order more.
pH: 7.6 (I tested away from where I added the acid. Hoping it's mixed enough over the last two hours to be accurate)
TA: 70
CH: 240
CYA: 55

 

[YippeeSkippy]

How about grabbing one of those pucks and hold it against the stained area and see if that lifts it? If it does you'll know its organic -Your FC is at the bare minimum for your CYA. What about CCs? -Your CYA is considered at 60, if it is anything greater than 50 you round up. Your ideal FC is 7. Refer to this chart to show you the balance between your CYA and your FC: Pool School - Chlorine / CYA Chart -Yes, two hours run time is plenty adequate for mixing -CH is just a skosh low, but people in the west often have overly high CH due to hard fill water and evaporation so you want to be cautious adding much. Here is a chart that shows your desired ranges: Pool School - Recommended Levels -I'm still unsure as to how you are chlorinating your pool? Please advise. Stick with the liquid chlorine if you're still routinely using those pucks.

 

[Rootyb]

How about grabbing one of those pucks and hold it against the stained area and see if that lifts it? If it does you'll know its organic -Your FC is at the bare minimum for your CYA. What about CCs? -Your CYA is considered at 60, if it is anything greater than 50 you round up. Your ideal FC is 7. Refer to this chart to show you the balance between your CYA and your FC: Pool School - Chlorine / CYA Chart -Yes, two hours run time is plenty adequate for mixing -CH is just a skosh low, but people in the west often have overly high CH due to hard fill water and evaporation so you want to be cautious adding much. Here is a chart that shows your desired ranges: Pool School - Recommended Levels -I'm still unsure as to how you are chlorinating your pool? Please advise. Stick with the liquid chlorine if you're still routinely using those pucks.

I'll see about getting in and holding a puck against the area. Honestly, I'm not sure if the light area or the dark area is the discoloration (and I'm not terribly excited about jumping in the pool to test. It's a bit cold). I've got a stainless steel wire brush, and have tried brushing both the light and the darker area, but didn't really notice any change.

I'm chlorinating via liquid chlorine exclusively. I'll add some more when I get home tonight.

I've emailed our PB, too, asking about it. They replied pretty quickly, and are sending someone out on Thursday to take a look at it. He said it looks like mottling, but that it's odd that it's localized in that one area.