We have a new pool and it has been sparkling until we got home from vacation 2 weeks ago. It was very green then. After the first week I managed to clear it up with chlorine(keeping it high 5ish), the PH (7.5ish) and alkalinity (80) were stable the whole time.

This week there have been blooms of algae and the ph dropped to below 7 the chlorine was still at 5. I got the ph up with baking soda, but the green on the walls and step kept coming back.
BTW, I live in Tampa so we get heavy rains every few days so I have had to also drain water at least twice since this started.Yesterday I took the water into the pool store to get help.

My numbers were FC 5, TAC 5, ph 7.2, TA 90, hardness 200, CYA 100. The guy there said that my alkalinity should be 100-120 and the ph should come up, everything else was ok.He gave us algaecide and told us to add it the day after we added the alkalinity up. He also said the ph would drop after adding the alkalinity up so I should add 8 oz of baking soda after a few hours of adding Alk-up.

We added 5 lbs of alkalinity up. This morning my numbers are chlorine 5, ph 7.8, and alkalinity 100, and the algae is gone. So why do I still feel like something is not right, lol.

I have my auto-chlorinator set at 4 the high is 5, should I keep it that way or turn it back to 3.5 as recommended by the installer? I use 3 inch pucks. The pool is 17,000 gallons and is in the sun all day.

So my questions are:

Is it true that alkalinity for a fiberglass pool should be 100-120?

Should I bother adding the algaecide since there is no algae?

Should I work (add chemicals) to get my ph lower or just check and see if it comes down by itself?

Should I be worried about CYA being 100?

Should I keep the auto chlorinator at 4 or should it be lower?

Thanks for any help!