Low pH & Alk, High CYA -- where do I start?

[wollerd]

Hi. I’m a long time lurker and a first time poster. A short history. I bought a home late last year with a 20x40 in-ground vinyl pool, 2 skimmers and 2 returns. We also have a separate spa (360 gal). TroubleFreePool has been a tremendous resource and I’ve gone the BBB route with the spa. I want to do the same with the pool. The previous owner didn’t pay any attention to balancing the water; he just threw in enough granular chlorine to keep it clear. After correcting a leak in the spa plumbing and witnessing the deterioration inside these pipes, I’m rather concerned about the pool which is a few years older. Anyway, I digress.

Since December, I’ve been in discovery mode reading through Pool School and perusing many forums. I’ve learned a lot and have a pretty good idea of where I am and where I need to go. I’ve just taken the cover off of the pool for the first time. The water level is above the eyeballs and below the skimmer. The water is clear and the liner is lined with green algae. Water temp is 55. I took the chemistry using the TF-100 test kit with the following results: FC=0, pH < 6.8, TA=20, CH=90, CYA=70. The weather outlook is for sunny and 70s for the next couple days and then some severe T/S and rain for a couple days.

My most pressing question is where do I start? Should I bring the water level up and start the pump, brush and shock to kill the algae? Or, drain 35-55% replacing with fresh to bring the CYA down? And, I presume that the pH/TA need immediate attention. Please point me in the right direction and thanks for all you’ve already done.

 

[Bama Rambler]

You're right about the pH & TA. I'd work on that after you raise the water level so you can get it circulating. Once you raise the water level to the proper height you may find that the CYA is about where you want it.

 

[linen]

Welcome to tfp, wollerd

Bama has you covered!

 

[woodyp]

Yep. Fill it, circulate it, shock it, initiallly take PH to 7.5ish, Fix the TA in range and adjust your PH again.

 

[wollerd]

Thank you all for the quick responses and insight. I've got the water level up and the pump/filter running. The pH=7.5, TA=130, CYA=40 (at ~55°). I added liquid chlorine (12.5%) morning and afternoon yesterday and again this morning to shock level (according to the Chlorine / CYA Chart). I thought it would speed up the "kill" by brushing the pool but that stirred up a lot of green. I probably should have just vacuumed that to waste I've gone through 11 gallons of chlorine and each test has shown .5 - 1 ppm FC prior to the next dose. It's supposed to rain all week with T/S on Wednesday... No real questions here but any advise or encouragement would be greatly appreciated.