Pink Mold In Pool

[ltpowel]

My pool is inground 14X28 and about 10,000 gal. The pool is clear as a bell, last week I saw a little pink mole around the seams, I brush it and added 1 gal. of shock. about a week later their's some pink mole on the seams again. but not as much as before. What is causing this pink mole and how can I prevent it.
Thanks, Larry
free chlorine=3
combine chlorine-0
chlorine=5
ph=7.5
alk=100
calcuim hardness=270
cyanuric acid=70
temp of pool water 84 F

[CarlD]

Hi Larry and welcome to the Pool Forum!

I think I can get you started on fixing this.

I think you mean mold, not a mole (a rodent).

First, if your FC =3, and your CC=0 then your Chlorine (total chlorine) cannot be 5. TC = FC + CC always. Something's not right with your tests.

But, putting that aside, here's what I can tell you: With level of Cyanuric Acid (CYA) of 70, you need for your Free Chlorine (FC) to always be between 5 and 10...now it's 3 or AT BEST, 5--the bottom limit.
You need more chlorine.
Your pH, Cal. Hardness (CH) and alk are all fine..no need to mess with them.

Here's what I suggest you do: Shock your pool with 3 gallons of regular unscented 6% ultra bleach. (If your liquid shock is 12.5% Sodium hypochlorite, you can use a gallon and a half of that instead). This should bring your pool up to "shock" level, around 20. If the free chlorine level stays high overnight, you should be OK. Meanwhile, run your pump 24/7, and brush your pool!

You should also go over to our sister site, PoolSolutions dot com and read up there.

Carl

[ltpowel]

I'm testing pool chlorine with OTO/Phenol testkit. Using 5 drops R-0600 to yellow side and got a reading for Chlorine of 5. The range is 1-3. and for the FC test, 10 ml pool water, 1 scoop DPD power (R-870) add 1 drop at a time of R-0871 until pink color disappears then multiply the numbers of drops by 0.5 and I got 3 ppm. I don't see a date on my reagent maybe they need replacing. Thank you for your help.
Larry