The best thing you can do to maintain this pool is to go ahead and take the plunge and buy the good Taylor K-2006 kit that we recommend. (See the testkit page in my signature.) Without it, you're going to constantly be saying exactly what you said in the post above, "my tester only goes to 5."

OR ---- I just looked at your information you put in the Pool Chart and see that you have the HTH 6-Way kit. Another option would be to purchase the FAS-DPD add-on kit that will give you the ability to test higher chlorine levels. The one you want is the K-1515 and is also on the testkit page.

Keep adding Borax until you get the pH between 7.2-7.8. After each addition of Borax, wait a couple hours, retest and redose.

Also, what is your CYA level? Are you only using bleach for your source of chlorine?