Hi all. This is my 7th year with our 27' round 48" deep above ground pool. It has been a pretty easy ride keeping things clear and clean....until last year. As stated in my first post...I had a few algae blooms last year...bought a TF-100 test kit...and found that I had some serious problems with some of my water chemistry. First problem fixed: CYA loomed around 100 so I drained around 60% of my water and refilled. Just finished refilling this morning and have the pump and filter running.

I ran some tests and here are my numbers....a couple of things are pretty far out of whack it seems:

FC: 0
CC: 0
TC: 0
pH: 7.2
T/A: 520 (yeah I did it twice to make sure)
CH: 700 (did it twice also...been filling from a well for years...we have hard water)
CYA: 40

It's about 70 degrees out...pool water is still COLD as we haven't had much sun in Central Illinois yet this spring.

I'm catching alot of crud in the skimmer socks right now and tending to the pool closely as I'm catching alot of stuff.

So where to start? There is algae present now...I'm assuming to start shocking it good and shoot for keeping chlorine level around 12?

I'm curious about the total alkalinity being so high. What causes it? What does it cause in return?