I have the strips from a local pool store. They are pretty expensive....I think 10 strips for $15.00 or something like that. I used 1 at the beginning of last year and 1 and the beginning of this year and I don't recommend them. It gives you a base line, but they are a little hard to read as they basically get grainier in color as the number goes up.

I have the aquarite and if you use their chart, you'll get pretty close anyway, just undercut the number so you don't overdue it! (besided the fact that the aquarite will give you a good reading after a good 12 hours or so after adding the salt).