It's much easier to test FC with these kits, and WAY more accurate, since you're not comparing shades of yellow. Rather, you're watching for a complete change from pink to clear. Besides, it will allow you to test for CC, which is a major factor when clearing up a green pool.

The K2006 is the most recommended kit around here. I know it's pricey compared to the OTO, but it will eliminate the need for pool store testing, which usually isn't as accurate anyway. It will save you its price tenfold in time, chemicals, and aggravation, because you'll catch a potential problem before it gets to be major and can get it fixed.

Janet