Ph pen problem

explosive82

explosive82

Well-Known Member
i really wasn't sure where to post this but hopefully this is the right place

Problem: i was gone for a week had my brother watch my grow (big mistake) and he opened my newer ph pen (bought about 6 months ago?) because he thought my old 1 was broke ( i dont think it was). Anyways long story short now both my ph pens are giving me different readings on my water and im not sure which to trust, i've calibrated them both (7.0 in the calibration solution) and i even double calibrated the newer 1 but they still seem to give me wildy different readings.

Ph pens in question:

old 1: http://www.amazon.com/Oakton-Waterproof-pH1-EcoTster-Solution/dp/B00FZSUN68
New 1: http://www.amazon.com/Oakton-EcoTestr-Waterproof-Tester-Range/dp/B004G8PWAU

i initially thought that ofc the new 1 would be right but i just don't know so i thought i'd ask and hear what roll it up had to say
 
A

az2000

Well-Known Member
The ph of my milk is around 6.6-6.8. That would let you know if you're in the ballpark.

I've had the kind of problem you describe when the probes develop a film on them from soaking in tap water, not storage solution. They become waterlogged too. I leave them uncapped for 8 hours (people say never let them dry out, but I do this and it helps). And/or, I soak in probe cleaning solution overnight. I try to use storage solution once a week, a few drops in the cap. Between those times I just rinse under tap water and put the cap on. When I get lazy and don't use storage solution I get different readings between two pens.

Dropping the pens in the nutrients causes really wacky readings. That's when I let them set out for 8 hours to dry (not capped), then calibrate and they're ok.
 
BROBIE

BROBIE

Well-Known Member
The PH1 is NOT temperature compensating, the PH2 is............ is your soup at a different temp than the cal solution?
 
explosive82

explosive82

Well-Known Member
BROBIE said:
The PH1 is NOT temperature compensating, the PH2 is............ is your soup at a different temp than the cal solution?
Click to expand...
this is possible although the difference in ph is like + .8 for the ph2 (thats to say that it is higher than the ph1)
 
explosive82

explosive82

Well-Known Member
az2000 said:
The ph of my milk is around 6.6-6.8. That would let you know if you're in the ballpark.

I've had the kind of problem you describe when the probes develop a film on them from soaking in tap water, not storage solution. They become waterlogged too. I leave them uncapped for 8 hours (people say never let them dry out, but I do this and it helps). And/or, I soak in probe cleaning solution overnight. I try to use storage solution once a week, a few drops in the cap. Between those times I just rinse under tap water and put the cap on. When I get lazy and don't use storage solution I get different readings between two pens.

Dropping the pens in the nutrients causes really wacky readings. That's when I let them set out for 8 hours to dry (not capped), then calibrate and they're ok.
Click to expand...
i've never used storage solution maybe that is the problem, although i've never had issues in the 1 1/2 years i've had this ph pen (the ph1) i usually rinse off the ph pen when i use it in nutrients since i have gotten it coated in gunk before i'm just not sure which of them to trust i can only imagine the new 1 is more accurate than the old?
 
A

az2000

Well-Known Member
How far off is the difference? @BROBIE makes a good point about temperature compensation. But, I saw a conversion chart that showed the difference between 10 degrees was only like 0.1. Maybe I'm wrong.
 
explosive82

explosive82

Well-Known Member
az2000 said:
How far off is the difference? @BROBIE makes a good point about temperature compensation. But, I saw a conversion chart that showed the difference between 10 degrees was only like 0.1. Maybe I'm wrong.
Click to expand...
anywhere between +.5 to .8 from what i could tell i use 1 of those droplet testers (with the little vial) and it was closer to the ph2
 
explosive82

explosive82

Well-Known Member
watered tonight and there was only a .3 difference so i'm not sure that it will make a huge difference although i wish i could decide which was right
 
relect

relect

Well-Known Member
I use a reagent test kit to cross reference my pen when testing pH and not another pen.
 
Hydrotech364

Hydrotech364

Well-Known Member
I usually fuk em up by using them as spoons but like someone mentioned temp is an issue with some pens.I stock up on the milwaukee cheap units .
 
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