I've found that the hannah PH testers work great and only have to be calibrated once a week. I've also used cheap PH testers with the same issues but not with my higher end Hannah PH tester. I use the Hannah HI 98130 which is an amazing tester. Its accurate to a .2 and the electrode will last you a long time. This PH tester is about $150 online but its well worth the money. You wont have to get a new tester for years. Also this tester is waterproof so if you drop it into the water its not a problem. If theres anything you dont want to cheap out on its your PH tester. Bad PH is a sure fire way of locking up your plants so invest a little and get a good one.




My grow log
http://boards.cannabis.com/grow-log/...-grow-log.html