Water turns green when I had water to pool

[SunnyOptimism]

I use Taylor K-2006, cannot change my signature?

Here are my pool water #.
Fc 2
Ph 7,5
TA 90
CH 120
CYA 40

My well water is FC 0.5-1.0, ph of 7.0

Thinking if I shock the pool before adding chlorine, would that prevent that?

Ok, I think I see the problem now - your pool water has far too little FC. For a CYA (stabilizer) level of 40ppm, your MINIMUM FC level should be 3ppm. And that is the LOWEST it should ever go in any 24-hour period. In fact, you should probably be running your pool's FC somewhere between 4-6ppm to maintain proper chlorination.

As well, I don't believe your well water is sanitary in the sense that it is probably ok for the purposes of using it on the farm, but I doubt you are able to maintain a constant 1ppm FC level especially without any CYA in it. In fact, I would be willing to wager that your well water falls below 1ppm FC and that algae and/or other pathogens are able to survive in it. Municipal water supplies can get away with 1-1.5ppm of FC with no stabilizer because the water is highly treated at the source (chlorine, ozone/UV, microfiltration,etc) and runs through relatively clean piping before it reaches your home. An underground well is no where near as clean.

So, you're taking suspect well water, adding it to your pool and DILUTING your already way too low pool FC to a level where algae can bloom. Then you shock your pool and kill the algae bloom you started with your fill water.

So, I would recommend two things -

1. You need to RAISE and MAINTAIN your pool FC at a higher level (4ppm to 6ppm);
2. You should shock treat your fill water BEFORE dumping it in the pool

Other PF'ers can chime in if they think I'm off base....