Indoor Ph-Meter calibrates wrong?

[zaQ]

I just got a new Ph Meter from a friend, its HM Digital PH-200. I calibrated it with the Ph soulution of 7.0 Ph that was in the box. And now the meter reads the solution as 10PH.

I use my tapwater as measurement because its always rock solid at 8.5 PH. And now shows it at 9.5PH?!

It says in the manual that you just press "CAL" button and it will do the rest for you...

Anyone have any suggestion?

 

[roadsidevendor1]

does yours have the adjustment screw below the word "cal"
if so then turn the screw counter clockwise until it matches the solution.

it doesnt read instantly...you have to give it about 5 min to self-adjust
to the temp of the test sample
the first few times..untill you get used to it

 

[zaQ]

does yours have the adjustment screw below the word "cal"
if so then turn the screw counter clockwise until it matches the solution.

it doesnt read instantly...you have to give it about 5 min to self-adjust
to the temp of the test sample
the first few times..untill you get used to it

No but it has a button instead of that screw. Im trying to go down from 10 to 7 but you can only put down until 8. Then it gives error, doh! This a 120 Dollar PH meter and works shiiiit. hehe

I guess i need to go get some more 4 7 10 Ph solution

 

[AndyBotwin]

I have that meter and it works great. I've used it with 4.01 and 7.0 solution from the bottles, and the autocalibration works in seconds. I did not use the packet that came with it, though. It's possible that you got a bad unit, but my guess is that your solution got contaminated somehow. Either way you're going to need to buy some solution, because you need to calibrate often and the included packet won't last long. A common problem I've seen on some of the review sites is people reusing solution. When I calibrate I pour a little into a clean cup and then throw it away when I'm done. It never gets reused and definitely never goes back in the bottle. Not saying you've done or will do this, just figured I'd point it out since I read where a lot of people were ruining a brand new bottle of solution because they wanted to save a few coins and reuse it.

 

[zaQ]

I have that meter and it works great. I've used it with 4.01 and 7.0 solution from the bottles, and the autocalibration works in seconds. I did not use the packet that came with it, though. It's possible that you got a bad unit, but my guess is that your solution got contaminated somehow. Either way you're going to need to buy some solution, because you need to calibrate often and the included packet won't last long. A common problem I've seen on some of the review sites is people reusing solution. When I calibrate I pour a little into a clean cup and then throw it away when I'm done. It never gets reused and definitely never goes back in the bottle. Not saying you've done or will do this, just figured I'd point it out since I read where a lot of people were ruining a brand new bottle of solution because they wanted to save a few coins and reuse it.

Do you use both calibrations fluid when you calibrate or only 4 or 7? Yeah i have more fluid on my shopping list

I got some Ph7 water from the Pharmacy and mixed the solution..

 

[AndyBotwin]

Do you use both calibrations fluid when you calibrate or only 4 or 7? Yeah i have more fluid on my shopping list

I have found that for the range we're looking at while growing, calibrating with 4 is the best. When I calibrate to 4 and test it using the 7 solution, it's dead on. When I calibrate in the 7 solution and test it in the 4, it's sometimes off by .1 or so. But I do use the 7 for quick testing just to make sure it's stayed correct between calibrations. I have a spray bottle that I keep filled with distilled water, and I use it to spray off the meter and the clean the cups between readings to ensure no cross contamination.

 

[akito]

I just started having the same problem with the unit after a year. It started calibrating my 7.0 to 10 then i purchased new ph down (which this new company might be garbage too) then i got the unit to adjust back down to 7. Changed the batteries.... saw a little rust in there so i cleaned it out with a qtip. Now i just dont trust the unit. Sometimes i just got to dump ph down in there to get it to go down. sometimes it goes up. I have fried 15 seeds so far :\. Hobby is definately becoming less fun with a fucked up pen. I guarantee i only got by last time bc of ph perfect nutes. I just dont know what to do bc to me this unit was $70. im prolly not going to buy another one. It just worked good for so long now it is untrustworthy :\. Also have yet to get an email back from the company...

 

[wg]

akito! good to see you brother, blast from the past right there. Glad you're still kicking. Who's the maker of the pen and what's the model?

Check this reference out; http://www.eutechinst.com/techtips/tech-tips26.htm - it's for a particular brand of pH meters but that's irrelevant, care is the same for all pH meters.


What I recommend doing is the thorough deposit cleaning;

For removing stubborn deposits and bacteria: Soak the pH electrode in a 1:10 dilution of household laundry bleach for 10 minutes. Rinse thoroughly before use.

Then getting some 4.0 and 7.0 calibration solution. Give it a go.

 

[akito]

yea i shyed away from the site when i seen a couple issues. Im still kicking for sure just waiting to get back on my feet. Its my first winter without a job :\\
HM Digital PH-200

 

[akito]

Just needed to replace sensor. now i can get back to work. I cant complain because the meter lasted over a year on its first batteries and sensor. Plus i droppe it a couple times..... Nice meter