Adding soda ash will increase your alkalinity. That's one reason we recommend borax instead of soda ash.

Green -- clear green with no slippery sides -- can be iron and/or alkalinity and/or pH. I've seen it, but I don't fully understand it.

1. Maintain chlorine.
2. Check the sides: on a vinyl pool, if there's no slime, it's not green algae!
3. Filter 24/7
4. Be VERY cautious about raising your pH. You need to do, but not too rapidly. If it IS iron, and you DO raise the pH rapidly, you can make a big brownish orange mess.
5. Get your OWN testkits. Links below.

Good luck, Ben

+ Here are links to the kits we recommend:
HTH 6-Way Test Kit @ Walmart
Taylor K2006A (3/4 oz bottles) @ Amazon
Taylor K2006C (2 oz bottles) @ Amazon