New Algae Problem

[scratchedup]

26,000 gal. liner pool in Georgia. 20+ years old. Autopilot SWG & Polaris 280 with a cartridge filter.
Really never had any trouble until this summer...
He had heavy rains ~ 2 months ago and the next day pool was green...not terrible but it took me 30 days of sweeping and cleaning the filter to get it back to normal...
Since then it has been perfect.
Yesterday the water was a little low so I added an inch or so of fresh tap water + a big glug of muriatic acid. Today the pools once again greenish...
What gives?
THX

 

[Texas Splash]

Two questions to get us started:
1 - Are you on a well?
2 - Can you post a full set of water test results?

 

[scratchedup]

Not on a well...county water.

I typically get the water tested at the pool store and the new store does not give me a print out. Everything looked good except the alkalinity was a little low.
Previously, I was instructed to add copper but I hesitated and got it clean through sweeping and cleaning my cartridge filter but now that the algae is back I added Mustard Algae Plus yesterday.

Today it looks pretty good. Was it mustard algae?

 

[duraleigh]

Other than just wild guesses, everything on the forum begins with valid, current test results.

Pool store test results cause us to just guess, too. Can your post your own results?