KH Director discrepancy

smartwater101

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Does the KH director allow you to submit a baseline or reference, in order to offset readings (similar to Alkatronic)? My Hanna and Red Sea tests are always spot on with each other. New reagents and I do multiple tests to be sure....
 

Fisherman Joe

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Great thread. Just setup my KHD tonight and it said the aquarium was 10.2 KH while my salivary said 8.0 KH.

I don’t have a volumetric scale so I was using a weighing scale to weight the water. I will buy a measuring cylinder and try again.
 

Gonzo74

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I have the GHL reference solution and find my KH director and Hanna checker to be within 0.2dkh of it. Accurate calibration of dosing heads 1 and 2 is critical to get an accurate measurement. Even a tiny amount of air in the reagent line will also cause issues.

Mine KH director wasn't very accurate for the first few samples but it kept getting better over the course of a week and now I trust it completely.

As an aside, the Hanna alk reagent has a very finite shelf life. If it's been open for more than 2 months I wouldn't trust its accuracy completely.
I agree with this and would go as far as saying more than one month.
 

AZMSGT

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Sigh... just set up my KH Director. I have taken 4 readings with it to be sure it was consistent. 6.6, 6.5, 6.5, 6.5

And the Hanna checker.. yea.. it reads 8.1 and has read 8.1 every time I used it.
That’s a pretty big split between the two.

I’m going to take a sample to the LFS and have them test it.

My tank has nothing in it accept water and the marco rock I cycled it with. My tank has all Tropic Marin Pro reef in it.

Really not looking forward to recalibrating the doser again.. but odds are I will need to.
 

smartwater101

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Sigh... just set up my KH Director. I have taken 4 readings with it to be sure it was consistent. 6.6, 6.5, 6.5, 6.5

And the Hanna checker.. yea.. it reads 8.1 and has read 8.1 every time I used it.
That’s a pretty big split between the two.

I’m going to take a sample to the LFS and have them test it.

My tank has nothing in it accept water and the marco rock I cycled it with. My tank has all Tropic Marin Pro reef in it.

Really not looking forward to recalibrating the doser again.. but odds are I will need to.
Is the offset not working for you? If you trust Hanna (I certainly do) I'd just make the adjustment and you should be good to go.
 

AZMSGT

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Is the offset not working for you? If you trust Hanna (I certainly do) I'd just make the adjustment and you should be good to go.
I want to be sure the numbers are correct before I go and use the offset. I want to be sure I didn’t screw up. Also if it comes down to using the offset, my issue is why doesn’t the $800 tool work better than the $60 tool?
 

Kyl

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Sigh... just set up my KH Director. I have taken 4 readings with it to be sure it was consistent. 6.6, 6.5, 6.5, 6.5

And the Hanna checker.. yea.. it reads 8.1 and has read 8.1 every time I used it.
That’s a pretty big split between the two.

I’m going to take a sample to the LFS and have them test it.

My tank has nothing in it accept water and the marco rock I cycled it with. My tank has all Tropic Marin Pro reef in it.

Really not looking forward to recalibrating the doser again.. but odds are I will need to.
Just observation, but I'm a recent KHD owner too that had large initial variances between my checker when testing the 7.5 reference solution (Hanna would be 7.8, KHD was 6.5). How is your waste container situated? I was getting about 1.2-1.3 dKH spread until I changed to a bulkhead drain cap for both waste and vent lines, versus dangling the tubes in the vessel. For whatever reason, that made all the difference. As well, make sure that reagent line is calibrated to the nearest tenth, it makes a large difference.
 

Fisherman Joe

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I recently calibrated everything.

Ran the reference solution and it came in at 7.1, not 7.5.

Im not too worried. I think the key is consistency and stability. If I can get the tank to constantly read 7.1 it won’t matter
 

AZMSGT

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Guess I'll be ordering the reference solution from GHL. I meant to get it initially but forgot it in the order.

@Kyl You referenced a bulkhead cap, can you please elaborate? Perhaps a Picture?

For reference here's my set up. Not pretty but it works for short distances on the lines.
IMG_1698.jpg


IMG_1699.jpg
 

AZMSGT

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My guess is they mean a 1/4 push connect bulkhead so the end of the line doesn't get submerged.

I was thinking that possibly too but those things are huge at the base. I would not be able to fit 2 in the cap of a jug. For my set up the vent and drain lines are just an inch into the cap. Very slim chance it will fill the jug unless something goes really wrong.
 

AZMSGT

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I did some pump recalibration and got the KHD to read 7.6, 7.5, 7.5 7.4. That’s closer to the 8.1 Hanna checker. I also took a sample to my LFS they checked it with a salifert kit and got 8.3. So the KHD is still off by .5-.9. So far... not impressed.
 

Fisherman Joe

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Thing is, it’s not like the unit is off, it’s that there is something that can’t be accounted for.

We can’t perfectly recreate laboratory conditions for the KH Director to read 7.5, 7.5, 7.5 etc.

The spectrophotometer May be more accurate but it’s not automated. It’s a trade off.

I used mine on the reference solution and got 6.6 and 6.7, should be 7.5, adjusted it 10% and now it’s working fine.
 

AZMSGT

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I ordered the reference solution to see where it’s at. Also, sent a bunch of screen shots in a ticket submitted to GHL.

We’ll see where it all goes.
 

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