As for a ph meter, I use a cheap one off of ebay.
altho i had to find out the hard way that it isn't really waterproof it works splendid.
and they fixed it for free once. altho i had to pay one way of the shipping and didn't had a meter for 2 weeks.
this one
http://cgi.ebay.com/WATERPROOF-DIGIT...3A1%7C294%3A50