If it's not iron you could still do a water dump, scrub and refill. I know it takes you a while to refill, but if you keep some chlorine in while filling it probably won't turn green again. You have to be diligent in keeping chlorine in it. I have a good well and can run it 24/7 so my first summer with a pool (the old one in my sig) I dumped it about 3 times before I found this site. Once I did, I got a good pump as the original was bad, I got the HTH 6-way and I managed to keep a very clean pool the rest of the summer. I never had to shock, but I tested daily, trusted the pool calculator to hit my high target and when chlorine dropped into the readable level dosed back to the high target. With that experience we decided to move up in pool size and haven't regretted it. I've not tested my well water for iron but given my experience it must be low or non-existent. If you have iron it can show up as a clear green, sometimes only at high chlorine levels, you should be able to see the bottom with no problem just a green color.