Yes they do...I got a message back from Oakton..pretty much what I thought it would be. Not much help..
Totally frosting up man...we'll have to get together and smoke test!!
GF24,
Your grow is looking fantastic!
Regarding your pH tester question....there are some standard practices you may or may not be aware of.....
Don't reuse the buffer after you test a solution. One dip and thats it, or else you contaminate the buffer.
Don't let you meter probe dry out. Store it in storage solution or tap water, not distilled. Long exposure to distilled water will damage the probe due to lack of ions.
Depending on the probe type, you may need to use a cleaner and rejuvination with a storage type solution. Also may be needed if the probe dried out.
You probably know this already, just thought I'd throw it out there.
Looking really nice, I'll be watching for the end game
just another old gardener
hope you don't mind another tagger along. Looks like you've got a great grow going and some fine looking ladies there! 
Hi GF - First of all:
Second - It's freaky about your PH meter - been going through almost exact same issues. Started not calibrating - was showing 8.5 and would give me an error message when I tried to calibrate to 7.0... I thought meter was going bad - however, I was near bottom of buffer solution bottle. I've always, always used good practices with PH buffer (never reused, etc.), but somehow there was still crap floating in it, and without a doubt it was BAD. Talked to hydro store and it sounds like it just happens - they go bad over time. Learn something new everyday. Anyway, got new 7.0 buffer and have been storing it in there (I keep a little bit in the cap at all times) and it's working better again and calibrates. OldGardeners tips are right on - and I follow them to the T. Still had this happen... Hope this info helps!
Also - I have a pretty good little petite dehumidifier. I'm not going to lie - it's no beast, but it works and it definitely helps. Here's a link to a post in my journal about it:
XLR8's BCNL Mixed Strain Hydro Grow 2011
Hit me up if you have any other questions about the dehumidifier or the PH pen. Honestly, I can't complain to much about my Oakton PH pen - it's been super reliable for 2 years now until this - and I'm sure it was just a buffer issue (crossing fingers).
i got one of them digital ones and when i got it there was this crusty stuff on it when i opened it, i guess i should take it and put some water in a little cup and let the meter sit in it...or can i use the 7.0??
Here's a question: Why do they look so damn tasty????
Comment: You're doing a fucking awesome job my friend!!
They are doing SO well..I'm thrilled! 
That is some good stuff (from what I hear of course). I was actually wanting to try a different GH nute as well. A few weeks back when I was at the hydro shop a rep from GH was dropping off their newest 2 part, Flora Duo. He mentioned that it was more "plant specific" if you catch my drift. Part A is
5-0-6 and part B is 1-5-4. I think it runs around $30 for both so that peaked my interest as well
I believe that PitViper is/was using Flora Nova and Floralicious and we've all seen those results
The 7.0 is also storage solution...put it in some of that..and clean thoroughly.
but do i gotta always have it sittin in some of the 7.0 or can i just leave it dry with the cap on it and will that be fine?? i dont know, i think its a pain in the ass if u ask me, im ready to go back and get the liquid tester shit....
shit i remember u guys were gettin on me like crazy about checkin the ph cause my plants were turnin yellow like crazy, now that i got all the shit i need to get the ph under control my plants have totally turned around, you can even see on one of the plants were the colas at the bottom are yellow chopped leaves and the whole tops of them now are all nice green frosty leaves its crazy lookin, but yea i think im gonna go to the chart deal, question for ya though, i've fed, fed, and fed, now i wanna water, what do u think??? and the water is 7.5 do u think i should put some phdown in it?? let me know what u think...
