I am getting a ppm meter as well as pH meter this week to acurately tell what it is i foung this on ebay ..can u tell me if it is a good one?? or nothttp://search.ebay.com/hydroponic-ppm-meter_Gardening-Plants_W0QQcatrefZC3QQcatrefZC6QQfposZQ5AIPQ2fPost alQQfromZR2QQfsooZ1QQfsopZ1QQftrtZ1QQftrvZ1QQsacat Z2032QQsadisZ200QQsaslcZ2QQsbrftogZ1QQsofocusZbs witch one would you go with???