KH Director reading is variable

**ss162400** · 29.04.2019, 14:07

Hi all,

I am having problems with the reading from my KH director.

I have recalibrated the pumps multiple times, and have also recalibrated the ph probe multiple times.

Have also flushed unit, vented regent etc. The regent tube is well under 70cm.

The readings are consistently variable, Salifert reading is consistently 7.7;

When I finish the sample pump calibration, KH Director reading is 7.7, but once its readings changed into 8.3, after I recalibrated the sample pump, the reading returned to 7.7. Sometime its reading changed into 7.4 or more low. I need often recalibrated the sample pump, so that I get the right reading.

Basically I need to check the sample pump every three days so that I can guarantee that the reading is correct. What should I do?

By the way, I have 2 units GHL Doser 2.1, I changed the Dosers, but the issue still stand here.

**ss162400** · 30.04.2019, 14:11

From the perspective of high-speed performance, Maxi must be better than Doser 2.1, but which one is more stable at high speed? If they are consistent, or MAXI is better. I think I can buy another MAXI to improve my current predicament. Which expert can tell me the actual situation? Thank you!

***Thilo*** · 02.05.2019, 15:30

The dosing amount is stable on both Doser versions. But the Doser maxi can't be used for the KH Director, because it's dosing amount is too much for the KHD.

Is the KHD measuring 7.7 dKH at the first measurement after calibrating only and the measures 8.3 at each measurement?
You're sure that the measurement cell is empty before every measurement?

**AQUA-digital** · 02.05.2019, 22:18

hello.-)
today i check my khd with the dkH reference and it is 7,5 and the second messuring is 7.6. i calibrate the pumps and ph on the 1st of march.
great system.

**ss162400** · 07.05.2019, 15:40

Originally Posted by Thilo

The dosing amount is stable on both Doser versions. But the Doser maxi can't be used for the KH Director, because it's dosing amount is too much for the KHD.

Is the KHD measuring 7.7 dKH at the first measurement after calibrating only and the measures 8.3 at each measurement?
You're sure that the measurement cell is empty before every measurement?

Hi Thilo,

Thanks for your timely reply! I am sorry for my late reply.

The KHD measuring reading is 7.7 dKH at the first measurement after calibrating only and Salifert reading also is consistently 7.7dKH.
but the measureing is variable rather than 8.3 dKH at each measurement. sometime it is 8.3 or 7.4 dKH, which is not the definite measurement reading after a few days

I clearly saw that the measurement cell is empty before every measurement.

Every few days, I need the calibrating to be sure the measuring reading is right. I am very confuse.

At once I bought a new GHL Doser 2.1 Pumps Maintenance Set to solve the issue, but the problem remains.

I think the unstable output of Doser 2.1 pump causes the result.