Green pool challenge

I have a 12,000 gallon concrete pool in central Florida and have not been successful in getting rid of the green algae. I tested the pool on Friday morning at a local pool store that seemed to be careful in their water analysis and got the following results:

FAC - 6
TAC - 6
CH - 260
CYA - 110
TA - 80
PH - 7.6
Pho - 300

I called another pool store prior to testing at the closer store and described the pool as green and asked for their suggestions. They suggested that I pour 3 or 4 2.5 gallon jugs of chlorine into the pool (7.5 - 10 gallons). I didn't have the courage to put that much in so put in 2 jugs (5 gallons) after having it tested when I went to buy the chlorine. I checked that night with my own Taylor K-2006 and the chlorine level was above 40 but I finally quit adding test drops. I checked on Saturday (1 day later) and the level was still above 40. The pool was looking as green as ever. I checked the chlorine level today (Sunday, two days later) and after adding 2 scoops of the R-0870 DPD powder to 10 ML of water, the water didn't turn pink which would seem to indicate that I have virtually no chlorine. Wow! What a difference a couple of days make. It is my understanding that the algae will cease to be green after it has been killed so the current green color tells me that it is still alive and well. I also checked the PH after adding all that chlorine and it was off the charts above 8. This morning, 2 days later, the PH has dropped back down to 7.6, presumably because the chlorine is no longer present. Should I have added Muriatic acid when I added all that chlorine? If so it would seem that the PH would now be way to low since the chlorine is gone. I also checked the CYA levels with the K-600 kit on Saturday night and I was not able to see the dot when the solution was only half way to the 100 mark so on the tube. If I was reading it right, the CYA level seems higher than the 110 the store recorded. Except for trying to shock it a couple of times, I only use liquid chlorine and a 3" Chlorine tab in the chlorine dispenser that lasts for weeks as I have a Pentair Intelliflo and apparently don't circulate enough flow for the chlorinator to work effectively.

What would you suggest that I do now? I have lost all credibility in trying to get the pool cleaned. My wife is suggesting that we bring in a real pool guy! Perhaps I'm too stubborn but I have to believe that we can do this ourselves.

Interesting observation. I just happened to notice that the PH test water that was not cleaned out of the tester, that read 7.6 a couple hours ago is now reading off the charts purple. Is that what happens when you leave the water in the tester for awhile?

Again, your help and advice is VERY MUCH appreciated.

DavidAJ

Hi. Has the pool store checked for iron and copper in the water? Green water that doesn't respond to high levels of chlorine if it's heavily laden with copper. But unless it is:

Here's what I would do, but it's up to you. Drain off 1/2 of your water and refill. Test everything with your K-2006 (use the 10ml or 5ml test for chlorine, not 25ml). If your CYA is still over 100, add sufficient bleach or LC to bring FC up to a minimum of 25ppm. In YOUR pool, if you go higher, even a lot higher--like double to 50 or 60ppm of chlorine it won't hurt the pool. It's not vinyl, so it's resistant.

If your CYA is STILL up like 150 to 200, I'd again drain off half and refill. Get that CYA down to manageable levels.