Bad Monitor or Bad Probe? pH

miwoodar · 07/18/2007, 03:32 PM

What happens when a probe goes bad?

My Pinpoint pH monitor began reading in the 1 to 2 range then actually dropped into the negative at one point. I tried recalibrating it but no matter how much I dialed the set screw I couldn't get it to start reading correctly again. Is this simply a bad probe? I've never had to replace one.

bertoni · 07/18/2007, 04:38 PM

The probes tend to fail after a while, and the symptoms you describe are reasonable for a failed probe. You could try cleaning it. I'd soak it in a solution of warm water and vinegar for 10 minutes or so, and try recalibration. How old is the probe?

miwoodar · 07/18/2007, 05:12 PM

Thanks Bertoni - I got it used. It worked great for ~6 months then went caput.

kff · 07/18/2007, 09:59 PM

More than likely your probe is bad, especially if it was allowed to dry out. The monitors almost never fail as they have very simple circuitry (essentially, a pH monitor is a voltmeter).

bertoni · 07/18/2007, 11:41 PM

I agree, but I'd try cleaning it.

miwoodar · 07/19/2007, 08:36 AM

I was never allowed to dry out. I'll try cleaning it then replace it if that does not fix the problem.

07/18/2007, 03:32 PM	#1
miwoodar Likey the bikey Join Date: Dec 2004 Location: Colorado Posts: 3,371	Bad Monitor or Bad Probe? pH What happens when a probe goes bad? My Pinpoint pH monitor began reading in the 1 to 2 range then actually dropped into the negative at one point. I tried recalibrating it but no matter how much I dialed the set screw I couldn't get it to start reading correctly again. Is this simply a bad probe? I've never had to replace one. __________________ Mike On hiatus. I'm either out riding my bicycle, playing with my family, or throwing ferts in my planted tank. Or working. I hope I'm not doing that though. Current Tank Info: 140 DIY Cube

07/18/2007, 04:38 PM	#2
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	The probes tend to fail after a while, and the symptoms you describe are reasonable for a failed probe. You could try cleaning it. I'd soak it in a solution of warm water and vinegar for 10 minutes or so, and try recalibration. How old is the probe? __________________ Jonathan Bertoni

07/18/2007, 05:12 PM	#3
miwoodar Likey the bikey Join Date: Dec 2004 Location: Colorado Posts: 3,371	Thanks Bertoni - I got it used. It worked great for ~6 months then went caput. __________________ Mike On hiatus. I'm either out riding my bicycle, playing with my family, or throwing ferts in my planted tank. Or working. I hope I'm not doing that though. Current Tank Info: 140 DIY Cube

07/18/2007, 11:41 PM	#5
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	I agree, but I'd try cleaning it. __________________ Jonathan Bertoni

07/19/2007, 08:36 AM	#6
miwoodar Likey the bikey Join Date: Dec 2004 Location: Colorado Posts: 3,371	I was never allowed to dry out. I'll try cleaning it then replace it if that does not fix the problem. __________________ Mike On hiatus. I'm either out riding my bicycle, playing with my family, or throwing ferts in my planted tank. Or working. I hope I'm not doing that though. Current Tank Info: 140 DIY Cube

07/18/2007, 09:59 PM	#4
kff Registered Member Join Date: Apr 2006 Posts: 57	More than likely your probe is bad, especially if it was allowed to dry out. The monitors almost never fail as they have very simple circuitry (essentially, a pH monitor is a voltmeter).