Drained pool and CYA already back up -please review my numbers! WTH?

[Donna P]

Hiya!
my Pool was drained 50% last Friday the 8th by a professional due to very high CYA/ Phosphate levels and metal staining . He came back that night and tested:
FC= 4
TC= 5
PH= 6.7
ALK = 80
CYA= 50
CH= over 800. Not much we can do about the calcium in the water here, I guess.
Added 8 oz. PH increaser

I tested Sunday:
FC= 2
TC= 1
PH= 7.2
ALK= 110
added 10 oz. liquid chlorine

Today-
FC= 3
TC= 4
PH=7.5
ALK= 110
CYA= 80
And The staining is back with a vengeance. ? I’m becoming a “mad” scientist for sure
Note:
-there are no chlorine tablets being used
- there is a heater, but it’s only a year old so nothing is eroded
-prior tests showed no iron in the water
-I use Jacks Magic Blue & CULator as maintenance
-for you chemistry smarties, our City water report shows Iron at >50 ppm, 600 MCL
It is crazy windy today and all kinds of muck is blowing around. I am in a area of Las Vegas where theres a lot of new home construction. So now I’m wondering if it’s something in our soil...? after all, there used to be tons of mining in Vegas.
i saw a post where someone had staining and pouring dry acid on it cleared the stain right up. That worked for me too, so until the Ascorbic acid gets here, should I add dry acid & see if it works? I think I can afford to decrease both PH and ALK.
Incidentally, does anyone else on here live in Vegas and have this problem?

Thanks, all.

 

[mknauss]

You are using the same water as I, Colorado River water. There is no iron in it.
What is your staining? If it is iron, a sock full of crushed up vitamin c tablets will clear it immediately. Does it?
Why are you using Jacks and a Culator? Those would only be needed if you have copper.

The testing difference is well, a difference. I suspect yours is correct. What were your tests before the partial drain? What is your CH test showing? How did you CYA get so high if you never have used trichlor tablets?
Is your test kit a K2006? Taylor does not make a K2000 kit.

 

[mknauss]

Copper stains can be removed by putting dry acid in a sock and rubbing it on the stain.

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[Donna P]

Thanks for the reply.
Vitamin C does remove it, yes. The use of Jacks is because the metal staining started back in Feb. I’ve given it Two Ascorbic treatments since then.
My numbers have been fairly consistent/ normal (even CYA) since install last year except for occasional low chlorine.
Pool store testing in Nov 2019 showed all normal except for phosphates at 400.
Same pool store testing in Feb. showed all within range except phosphates at 1000
I just got the Taylor Kit a Couple weeks ago, so prior to that I was only testing PH, chlorine & Alk. and again, they were fairly normal except for occasional chlorine dip.
I was using the tablets prior to last month, before the drain. Could the residual water affect the CYA level that much right now?
Both pool store tests showed zero iron and copper, btw. I could do a sock cleaning, but it covers the entire pool
My kit is a K-2006, sorry.

 

[Donna P]

This may or may not be of any importance, but there are no trees, leaves, grass or basically anything green around here. But there are crazy winds and a lot of desert dust flying around. It’s So bad today that the dish satellite has been cutting out all day. I’m afraid to see what the pool will look like in the morning ?

 

[mknauss]

I was using the tablets prior to last month, before the drain. Could the residual water affect the CYA level that much right now?

I suspect the CYA in your pool before the partial drain was much much higher. With your current result, it was likely near 200 ppm.

 

[Donna P]

Ohhhhkaaayy, I’ll give it another AA treatment but the fact that this staining came back SO quickly and much worse than before a refill really concerns me.... :-(

 

[Richard320]

I suspect the CYA in your pool before the partial drain was much much higher. With your current result, it was likely near 200 ppm.

I'd wager large sums of money on that.

A tip: when a pool store writes "99" as the CYA level, it means "Off the scale". The guy who drained it either saw that and assumed it was right, or he's just as bad at running the CYA test as the rest of them. 200+ CYA is rather easy to attain. My pool was there when I bought the place. Given the built-in margin of error that comes from triple and quadruple dilution, I was somewhere between 220 and 240 CYA. You and me, our pools stay open year-round even if no one gets in for several months. And we don't drain down below the skimmers to protect the pipes from freezing. Nor do we get snow and heavy rain to dilute things. So CH and CYA just build and build and build.