KHD value high - tried known fixes

[r21]

How is your sample intake routing handled? Is the filter mounted for horizontal water draw? Is your KHD mounted above the doser 2.1?

There are a lot of factors that can mess things up with the KHD. If everything is operating properly (measured and calibrated) it will be near dead-on with an accurate reference standard.

Sample line is ran into the sump about 3 ft run, filter is mounted vertically

 

[r21]

So it appears weighing the calibration fluids to 0.1ml is by far more accurate, the average of the 3 calibration runs I made was used in the dosing pump setting and now the last two measurements using the 7.5 reference fluid have been 7.4 and 7.2 just running another one now. I think GHL should update the document and change their method in the instructions, measuring lines or using a measuring cylinder is just too inaccurate - I think its just luck if you manage to get the value correct using the official method - I had a 2ml discrepancy in the reagent which is a 30% difference which is probably why my result were around 30% off.

 

[Kyl]

Yup, weight is superior to visual acuity for the human eye, especially since cheap graduated cylinders probably have an accuracy of like +/- 5-10% at the best of times, plus many sort of guess with the capillary action of the water in the cylinder too, etc.

 

[r21]

My tank water is now measuring at 7.3 which is roughly what I'd expect from freshly made up Tropic Marin Pro, now I know the dKH and can raise it to my preferred 8-8.5 range. Thanks for the help everyone

 

[r21]

So all was well for a few days and I started noticing my KH was dropping despite dosing the same amount of Alk a day, growth couldn't account for it so I retested with the reference fluid, 2 readings as that's all I had enough left for. 6.2 and 5.7 - how could it have drifted so far from accuracy is a matter of days, it makes me seriously question the accuracy of the product, it shouldnt require a phd to setup, I've been very accurate and careful of how its been setup and I'm now in a position where I have no more reference fluid, used an entire bottle trouble shooting issues and I have no confidence in the value being reported!!

 

[loli2010]

I had very stupid problem. KH readings were droping slowly while hanna was constant and this morning it droped by 1,1. I flushed measurment cell and while flushing I saw that fluid and air were raising up through vent hose. Vent hose outlet and waste water outlet were to close to each other and vent line was sucking waste water in. I moved them away and now measurments are ok.