Ph probe

[pastelball]

So i calibrated my ph with calibration fluid. Now my ph on the probe was 7.64 now its at 7.40. I have a ph pen and its at 7.6. Should try to calibrate ot again and get a new one. This one is maybe year and half old.

 

[jml1149]

There are two "tips" I have when calibrating pH probes and get odd results:

1. Make sure you float the calibration solution in your tank for 15-20 minutes before you do it to equalize temperature
2. If you're using the Milwaukee long flat ouches, you need to shake the snot out of the probe in the solution to make sure all the bubbles are out.

I've had pH calibration come up weird, then recal'd using these and it's helped.

I think the chances of your pH actually being 7.4 are pretty low. What's your alk?

 

[Terence]

What does it read in the 7:0 solution immediately after calibrating? What does the ph pen read when you put it in the calibration solution?

 

[pastelball]

I will check. I will say that the ph is hold steady now.

 

[pastelball]

Ok, i recalibrated. The apex probe is reading the same as the ph pen. It also reads the same as the calibration fluid.

Thanks for the help.

 

[pastelball]

So this morning at about 4:30 am my ph dropped to 7.06 then fell to 2.08 at 5:00 am. Grabbed the ph pen it was reading 7.9. Unplugged the probe and reconnected it no change. I would say the probe went bad.

 

[pastelball]

Well, got the new ph probe today. Calibrated the probe with 7.01 and 10.1 calibration fluid. I can get it calibrated but, when i put the probe in the tank it reads 6.30. I check with a hand held ph pen it reads 7.8.
When I put the probe back in the 7.01 calibration fluid it reads 7.12. Not sure what is going on.

 

[jml1149]

Did you try the two tips I posted earlier? Floating the solution and shaking the probe in the solution to get all the bubbles out? I have seen what you're describing before and it usually resolves when you shake the probe in the solution before calibrating, for me.

 

[pastelball]

yes, did what you what you posted. Opened a ticket with Neptune about it. After talking with them we found out it was a bad float switch throwing the probe off.

 

[jml1149]

Like an electrical interference problem? That makes sense, just curious, do you have a grounding probe in your tank? (here comes the fury)

 

[pastelball]

I don't, as that is basically what the was doing. I unplugged everything that went into the tank. Got down to nothing powered, so last thing to try was the b.o.b on the pm1 which all it does is switches ground. I measured for current even when stuff was powered up and nothing.