I always store my pH meter wet in the 7.0 calibration solution. simply dip it in there before putting on the cap.
I always swish my meter tip around in plain water before tests for the exact concern you have re: tainted.
How quickly they get tainted will be dependent on how much calibration solution you're using to adjust it in. I test mine in about 6 ozs of solution and I'm more likely to change it out at years end than because I think it tainted.
my meter measures to two decimal places. if that last one fluctuates a bit, I'm not too concerned.
I generally calibrate it when I use it. Bear in mind though, that I don't test all that often. generally only between changes.
When I bought my meter it was $20 USD. the same thing is now, I believe, $40. something along 40-50 wouldn't be all that out of line. Of course, there are always test strips and drops.

pH meters are a pain to us. Always store in solution until you use it again in the morning or just lay it on the bench, doesn't make much difference that we can tell. Got one down now and it's only 1 month old, it always had solution on it when not in use, had a special cap just for that. The old cheap Hanna Checker 1 (we have two)is the back-up and it's calibrated before each use. The 1 to 2 hundred dollar units are nice and easy to use. Plus calibration is a snap. Auto turn off is a great feature.
We have two shot glass's that we pour calibration solution into, just enough to cover the bulb, and discard after one use. Rinse probe with tap water after each use
We keep close tabs on pH for the best nutrient uptake possible and constantly healthy plants.
The more we learn and know about the water the more successful our plants are.
"Doing 10 with no Chance of Parole"

Here is a link that might be useful:

I can't remember who said it but I should of listen to his/her advice and just stuck with the drops! They are a pain in the a$$ to be honest, I also have a cheapish hanna and it takes forever to get a reading, then it need to be calibrated every few times. Anyway it is back in its carboard box and I am back to drops, which I don't even really use much these days either as after a while you get to "know" your water.

The new Oakton� Waterproof EcoTestr� pH 2 was recommended to us by a Dallas Hydroponics dealer. We have only used it for a few days now "but" this is the fastest meter we have ever used. It only gives one point reading like 5.9 - 6.2 etc. "but" so far has been a delight to use. The cost was very low. Forum may block the link.
"Doing 10 with no Chance of Parole"

Here is a link that might be useful: Eco

I am a commercial hydroponic farmer and do use my instruments with great frequency, but what I can tell you is that the cheaper meters are not worth the hassle. Whether or not you keep them in the buffer solution, they will break, and most importantly slip from calibration. As far as the Oakton eco tester goes, I would avoid it at all cost. There are serious issues with that meter and most of what Oakton makes. In two years I went through four of them. The only reason I kept getting them was because my supplier would replace them for me.
I have four reservoirs that I continuously have to monitor so I finally broke down and got continuous read PH monitors for each. These stay in your reservoir and give you readings at a glance. They do not have to be stored in buffer solution, and from my experience are much higher quality probes for around the same price as the upper end Oakton handhelds. So far, the best performer is my PH mini doser from AmHydro which also doses when the PH exceeds a set value. This is not a cheap option however. Those units cost me around $800 from what I remember.
A more economical option for constant read would be a Hanna constant read monitor. It is also only around $80 and stays fairly accurate. This does not dose, but I use them for my propagation tanks that I only adjust once a day and don't need a constant PH (because they only water once a day as apposed to my large reservoirs which are constantly pumping to NFT).
Hope this helps.

As my tiny 1 Oz. bottle of indicator solution gets closer to empty I often contemplate the purchase of a Ph meter. While on a business trip I stopped at a Hydro shop in PA to check the place out. I picked up an extra Kg. of MaxiGro and asked for a bottle of Ph Indicator solution. The salesman stated that they didn't carry it because it is not accurate and tried to sell me a 35 dollar meter that looked like a piece of crap. When I got home I looked through my catalogs and started pricing meters and adding things up. 1-3 different calibration solutions depending on how many calibration points the meter has. I guess the more calibration points - the more accuracy? Then cleaning solution and storage solution? I think I'll stick with my single solution-solution. That would be Indicator solution. However this is a very good post. It's always good to find consumer report type information that isn't loaded with spam.
Thanks again,
~Ken~

Ya hardclay7a, unfortunately there are a lot of sales people out there like that. That's a clear and obvious tip off at an attempt to just get more money out of people. That type of thing really upsets me, and I probably would have nicely put down any products I had planed to get, and just walked out of the store with nothing (and get my stuff elsewhere). To me that's equivalent to steeling money directly out of my wallet, and people like that don't deserve a penny of it.

It's one thing to give an opinion about something (even if untrue, as in this case), but it's another thing altogether to ignore what works for the customer, as well as what the customer want's just to try to push something they want to sell. That's when it crosses the line from an opinion to steeling for me. But unfortunately most people new to hydroponics don't know any better, and just believe what the salesperson tells them because they think they should know, after all they work there. So they just trust whatever the salesperson tells them. They rip off so many people that way it just infuriates me to even hear about it.

P.S. I also agree that freshlygrownfarms post was informative, and it's always good to hear about peoples personal experiences with products they have used, as well as hear about what works best for them. I found it particularly good to hear that the continuous read meters are much more likely to be more accurate and better quality. Right now I don't have a need for one, but I hope to in the future.

We bought a $200.00 Hanna Combo meter that never worked and was replaced with other Hanna Combo meters that didn't work either. Finally getting our money back and for sometime we stayed with the little entry level meter. We still have two of them that work well but slow and have to be calibrated often. We now have a Martini EC59 TDS meter and a Oakton PH2 and a HM PH-200 meters.
The HM is down after 2 months use but the Oakton is going strong and fast.
We know everyone on here knows more than we do, but we do know (from Experience) with aeroponics you can lose the entire crop in hours if the pH (or) TDS gets bad, and they can change for the worst quickly.
The drops or paper indicators are not practical IMHO for daily use when caring for multiple systems.
We may have to step up to the continouos readers someday but at this time are trusting the meters we have and just watch for odd or unusual movement in readings. Then check one meter against the other.
Each system has it's own whiteboard and all readings are recorded and watched.
"Doing 10 with no Chance of Parole"

"UPDATE"
"freshlygrownfarms" was correct in his advice to stay away from the Oakton ph meter. Very much a road to bad readings and crop problems. Meters are a must in aeroponics so guess we will have to step up to the continuous meters.
"Doing 10 with no Chance of Parole"

Why wont the pH drops work for you?