In my experience, try to get those cost in range from $30-$70 is fine, quality & reliability issue, concern.
For used PH pen, u may want to consider my offer here
clik the link to see
http://www.arofanatics.com/forums/sh...37#post4922537
Quote:
Originally Posted by johnny_fantics
What is the cheepest pH pen out there i can get? Feel like getting one.
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