Confusing KH readings on Hanna DKH checker

[SAMS]

Hi,
I havejust done a full set of water tests on my tank and the KH result is very confusing.

It is a 1000L tank and I did a water change yesterday approximately 28 hours at the time of writing.
Here are the results below:

NITRATES:
ABOVE 4PPM ON LOW RANGE RED SEA NITRATE PRO TEST
BETWEEN 4-8 PPM ON HIGH RANGE RED SEA NITRATE PRO TEST

PHOSPHATES:
0.02PPM ON RED SEA PHOSPHATE PRO TEST

SALINITY:
1.025 SG ON MILWAUKEE MA887 DIGITAL SALINITY REFRACTOMETER

CALCIUM:
500PM ON RED SEA CALCIUM PRO TEST KIT

MAGNESIUM:
BETWEEN 1080-1120PPM ON RED SEA PRO TEST KIT

KH (THIS IS WHERE IT GETS CONFUSING)

I did 3 checks on the Hanna DKH checker and got the following readings:
2.7 DKH
4.3 DKH
3.6 DKH

But on the Red Sea KH Pro Test kit I did 2 tests and it came back at either 8DKH or 8.5 DKH.
Any help would be much appreciated.

 

[SAMS]

Sorry I forgot to add that I had used Citric acid when cleaning all of the testing vials and I thought I had thoroughly washed them, however during testing I did notice that they were slightly sticky.
Could this effect the readings?

 

[mcdrichj]

Sorry I forgot to add that I had used Citric acid when cleaning all of the testing vials and I thought I had thoroughly washed them, however during testing I did notice that they were slightly sticky.
Could this effect the readings?

Using an acid can definitely throw off your readings! An acid will neutralize alkaline molecules. So if there is any acid left it will decimate alkalinity readings.

Edit: This would explain why your other kit is reading properly.

 

[Claus84]

Hi,
I havejust done a full set of water tests on my tank and the KH result is very confusing.

It is a 1000L tank and I did a water change yesterday approximately 28 hours at the time of writing.
Here are the results below:

NITRATES:
ABOVE 4PPM ON LOW RANGE RED SEA NITRATE PRO TEST
BETWEEN 4-8 PPM ON HIGH RANGE RED SEA NITRATE PRO TEST

PHOSPHATES:
0.02PPM ON RED SEA PHOSPHATE PRO TEST

SALINITY:
1.025 SG ON MILWAUKEE MA887 DIGITAL SALINITY REFRACTOMETER

CALCIUM:
500PM ON RED SEA CALCIUM PRO TEST KIT

MAGNESIUM:
BETWEEN 1080-1120PPM ON RED SEA PRO TEST KIT

KH (THIS IS WHERE IT GETS CONFUSING)

I did 3 checks on the Hanna DKH checker and got the following readings:
2.7 DKH
4.3 DKH
3.6 DKH

But on the Red Sea KH Pro Test kit I did 2 tests and it came back at either 8DKH or 8.5 DKH.
Any help would be much appreciated.

How long has your kh reagent been open? My checker was reading low until I opened a fresh bottle, had probably been open a month or 2.

 

[SAMS]

The KH reagent has been open since august time, however it is still in date and is kept with the lid sealed in the Checker box.

Thanks for the notes about the acid residue.
It is best to clean them in RODI, then citric acid, then RODI again and then leave to dry?

 

[W1ngz]

Instead of rinsing them with anything that could throw the test, I just rinse my vials with RODI water after use, then store them filled with RODI. A quick rinse with tank water before use, and good to go, with no residual reagents or anything else.

 

[SAMS]

Thanks for the suggestion.

 

[Claus84]

The KH reagent has been open since august time, however it is still in date and is kept with the lid sealed in the Checker box.

Thanks for the notes about the acid residue.
It is best to clean them in RODI, then citric acid, then RODI again and then leave to dry?

I'm not suggesting that is definitely the cause in your case but for reference mine was also well within date and stored tightly sealed in the box it came in.

 

[MERKEY]

I

Hi,
I havejust done a full set of water tests on my tank and the KH result is very confusing.

It is a 1000L tank and I did a water change yesterday approximately 28 hours at the time of writing.
Here are the results below:

NITRATES:
ABOVE 4PPM ON LOW RANGE RED SEA NITRATE PRO TEST
BETWEEN 4-8 PPM ON HIGH RANGE RED SEA NITRATE PRO TEST

PHOSPHATES:
0.02PPM ON RED SEA PHOSPHATE PRO TEST

SALINITY:
1.025 SG ON MILWAUKEE MA887 DIGITAL SALINITY REFRACTOMETER

CALCIUM:
500PM ON RED SEA CALCIUM PRO TEST KIT

MAGNESIUM:
BETWEEN 1080-1120PPM ON RED SEA PRO TEST KIT

KH (THIS IS WHERE IT GETS CONFUSING)

I did 3 checks on the Hanna DKH checker and got the following readings:
2.7 DKH
4.3 DKH
3.6 DKH

But on the Red Sea KH Pro Test kit I did 2 tests and it came back at either 8DKH or 8.5 DKH.
Any help would be much appreciated.

Oh man I feel you on this one!!

I get 3 different readings consistently from 3 different test kits.

Red sea 14-17ish on regular depending if I test fresh salt mix or 1 of the 2 tanks.

Hannah 9-12 on regular

Giesseman 8-10 on regular.

I get the lowest fluctuations with giesemann.

I have stopped trying to get it to a certain number and just hold it steady where it is.

I had to stop using hannah so much due to cost and availability of regents outside of amazon due to a bunch being crap.

I tested numbers for a month and wrote down what each corresponded to each other.

So now I can use red sea and know when it read 11.4 it is 8.2 on giesemann.

I'm not saying this is good to do but I got tired of feeling crazy and decided this was best for me.

Although because my wife was the one doing all the testing...steady hand and eyes.... now my wife says I can get a trident or monitoring system to make it easier hahahah

 

[PghReef]

Instead of rinsing them with anything that could throw the test, I just rinse my vials with RODI water after use, then store them filled with RODI. A quick rinse with tank water before use, and good to go, with no residual reagents or anything else.

Exactly what I do