Reef Factory reagent - can it go off?

[lmfbs]

I'm having a problem with my Reef Factory kH keeper plus which I bought second hand. It was working for the previous owners and they're very trustworthy.

I've posted about it here: https://www.reef2reef.com/threads/kh-keeper-plus-no-reagent.1040488/

The reagent that came with it was the Reef Factory brand, but 'expired' in Dec 2023. However, it is HCL so...can it even go off in an unopened container? I mixed it according to the instructions (1:9, I mixed 1L) though admittedly, it's possible my measuring tools weren't accurate enough. I've ordered some measuring cylinders from a lab supply company to try to take this part of the error potential out.

The issue I'm seeing is "Out of reagent or water from the aquarium" and the dkH reading is 15, which I understand is the error state. My current best guess is this is a measuring error when mixing reagent, but would we expect to see a failure to mix reagent properly come up with this kind of error or would it just test the value wrong?

The actual test appears to be running fine (taking the right amount of water, and adding reagent from the right place etc). The pH measurement from the probe is spot on compared to my other pH meter.

Any hints greatly appreciated!

 

[lmfbs]

Alright - I've got some more information.

I went with the assumption that the reagent is the thing that's wrong. I mixed up a small batch of reagent (10ml reagent, 90ml RODI). Didn't work. So I increased the concentration by adding 5ml of reagent (total: 15ml reagent, 90ml RODI).

Now I've got a reading. The dKH is wrong (hanna with brand new reagent tests at 7.4, salifert at 7, kH keeper at 12.16), but at least it's something!

Does this point to my reagent being bad/mixing being bad? Am I messing up my 1:9 ratio somehow? I've got measuring cylinders arriving today, so hopefully that helps.

 

[lmfbs]

Alright - I'm now feeling reasonably confident the issue is not the measuring. So, any ideas what could go wrong with the reagent?

 

[gbroadbridge]

Alright - I'm now feeling reasonably confident the issue is not the measuring. So, any ideas what could go wrong with the reagent?

I doubt there is anything wrong with the reagent if it was unopened.

It is simple HCl and does not go off.

The issue is likely with the calibration of either the reagent dosing head or the sample dosing head.
Did you follow the instructions and calibrate taking into account that the mass of saltwater is not 1 gram per ml?

 

[Randy Holmes-Farley Verified Community Expert]

The pH measurement from the probe is spot on compared to my other pH meter.

Any hints greatly appreciated!

Just as a general thought, that’s not a very convincing argument for accuracy if both probes were calibrated with the same calibration fluids by the same person in the same way.

 

[lmfbs]

Just as a general thought, that’s not a very convincing argument for accuracy if both probes were calibrated with the same calibration fluids by the same person in the same way.

They were calibrated with different calibration fluids, about a week apart, if that helps.

 

[lmfbs]

I doubt there is anything wrong with the reagent if it was unopened.

It is simple HCl and does not go off.

The issue is likely with the calibration of either the reagent dosing head or the sample dosing head.
Did you follow the instructions and calibrate taking into account that the mass of saltwater is not 1 gram per ml?

I did, but I'll recheck tonight.

 

[lmfbs]

Alright - the tankwater pump was perfect, but the reagent pump I clearly didn't calibrate right. When I tested it, it's supposed to pump out 5.0ml. Mine pumped 1.8ml. I've recalibrated and it's working perfectly.

Thanks everyone for your help!

 

[gbroadbridge]

Alright - the tankwater pump was perfect, but the reagent pump I clearly didn't calibrate right. When I tested it, it's supposed to pump out 5.0ml. Mine pumped 1.8ml. I've recalibrated and it's working perfectly.

Thanks everyone for your help!

Good to hear :)