Does the tip need to sit in the buffer solution or distilled water?

Nope. Whatever it reads after a quick shake in the water is correct. UNLESS you bought a meter off of ebay for under 50$. Those are never right. I bought one off ebay and it gave me 12 different readings from the same buffer solution. Spend the 100$ on a real ph meter it is worth it as those cheaper meters dont actually work and its like throwing 30$ away!! I just re-checked my oakton after almost 14 months and it still reads 7.0 exactly on the 7.0 buffer solution I have! Oh if you add ph up or down, make sure you mix well before re-checking, there's pockets of low and high if not!

I have a millwalki, and store it in ph7.0, my friend uses distilled H2O. I don't think it matters just don't let it dry out.
but then they make some that are sold as continous reading??
better send a note to the mfg.

ok thanks Bro. My ph readings keep rising .Why?

I think that is normal,mine always goes up a little everyday,another reason to change nuits weekly

I don't know anyone who uses Ph up,if you have already used ph down, all your doing is making salt they won't,can't use.better to drain and refill with new nuits

always rinse real good before returning prob to storage

While what daddy nobucks said is the correct info that you should follow, I usually just shake mine off good and shelve them, and do not put the caps back on. I think maybe the fact that they get used at least twice every day they stay clean. Plus I clean them off in florakleen solution if they get gunky (I am also refrerring to my tds meter).

some bad info here, so far ... if you have a Milwaukee pen, KEEP IT WET ! ... that's what the cap is for ... if it dries out, it will be permanently ruined ... I use the same base water for storage, as I use to prepare for my plant ... periodically, check it for accuracy against the buffer solution ... my Milwaukee pen always stayed spot-on, I occasionally checked it against litmus paper, to make sure ... when all else fails, read the instructions , or check with the manufacturer ...

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not a pen,a 802 multi-meter
and I keep the probe in 7 solution,it is always right
Ph and TDS/EC

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My hana meter says never leave in distilled or R/O it will mess the probe up. Either solution or probe cleaner. Keep a litlle in the cap so it's always moist.

Thie directions for my meter said to rinse off with distilled water before storage, absolutely nothing about keeping fluid in the cap, I think I wouldve remembered that. Does anyone else do this?

the reason for the rinse is so you don't contaminate the storage solution.

allforme said it best, KEEP IT WET

my first Ph meter required referance electrodes as well as a Ph electrode

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I keep my ph milwaukee meter in cap full of ph buffer 4.01. But I am now having a hard time calibrating the 4 ph