水草情迷

I just brought a SAGA ph controller but I cannot calibrate the controller to the right value. I follow the instruction to put the ph electrode into ph7 buffer soluation then adjust the value to 7 using the ph7 knob. after that I put the electrode into ph4 buffer solution then adjust the value to value 4 using the ph4 knob. after all the calibration, I put the electrode into my tank but the value read 3.8x. it is not possible. then i put the electrode into ph7 buffer soluation to check the reading but the reading shows 5.7x.

is the controller is out of order or i did something wrong. Please help!

你冇 cal 錯呀, 睇黎係有問題了

Did you wait for long enough on each calibration? SAGA's controller take a little longer to reach the right value, up to a few min if pH value vary by more than a few degrees. And if you want dead accuracy, you have to go back to 7, cal again, back to 4, cal again... back and forth a couple of times.

Did you wash the probe by distilled water and shake dry it before moving from pH 7 solution to pH 4 solution? This step is very important or contemination will occur which greatly reduce the accuracy.

Was the probe stored in distilled water when you got it?

I only washed the probe with tap water before move from 7 to 4 solution and I did shake it dry. I will try distilled water. YEs..The proble was stored in distilled water. I will try it again tonight. Thanks!

The exact same thing happens to me as well. After calibration, I put the Pen back to the "4.01" solution to read and shows 4.8 instead of 4.01! And it takes very long time (around 10 mins) for each calibration...

will try Macbrush suggestion tonight as well, thanks.

I finally took the contoller back to the shop and confirmed that the probe is defective. I got a replacement and it is working fine now.