KHD Titration Error

[Crimsonvice]

I have a KHD that was running fine for two weeks and then my alk readings started to increase and finally it started to give me "Error: Titration takes too long."

I was trying to troubleshoot it with Vinny, but the company is on vacation for the next two weeks. Does anyone have any suggestions? I already re-calibrated pH probe and pumps, vented reagent tube, and increased my sample to 90 mls.

 

[Dan_P]

I have a KHD that was running fine for two weeks and then my alk readings started to increase and finally it started to give me "Error: Titration takes too long."

I was trying to troubleshoot it with Vinny, but the company is on vacation for the next two weeks. Does anyone have any suggestions? I already re-calibrated pH probe and pumps, vented reagent tube, and increased my sample to 90 mls.

Can you determine your system’s alkalinity with a test kit?

 

[Crimsonvice]

Can you determine your system’s alkalinity with a test kit?

Yes. 9.2 is Hanna Checker.

 

[road_runner]

I have a KHD that was running fine for two weeks and then my alk readings started to increase and finally it started to give me "Error: Titration takes too long."

I was trying to troubleshoot it with Vinny, but the company is on vacation for the next two weeks. Does anyone have any suggestions? I already re-calibrated pH probe and pumps, vented reagent tube, and increased my sample to 90 mls.

This means reagent is not going through the device at one point or another. Did you check if there is any bubble in the tubing?
Do you see reagent going through the tubing?
Do you hear the titration peristaltic pump working and routating?
Basically go through the reagent path from start to end and see if there is disconnection, bubble or blockage..

 

[road_runner]

@Ditto. Not sure if he has something to add..he is the ghl wizard here ha ha

 

[WWIII]

Does the ph value drop down while the test is happening? Should be able to watch it go down to under 4.5 then it will give the result.

Are you sure the doser heads are all operating flawlessly and calibrated correctly? No blue chips or sticking.

Have you checked for and removed the tiny inline filter inside?

@Ohashimz nailed it. Not getting enough acid some way? some how.

 

[road_runner]

..

 

[Crimsonvice]

This means reagent is not going through the device at one point or another. Did you check if there is any bubble in the tubing?
Do you see reagent going through the tubing?
Do you hear the titration peristaltic pump working and routating?
Basically go through the reagent path from start to end and see if there is disconnection, bubble or blockage..

It is definitely going through the tube. I have had a GHL Doser for years, so I am pretty comfortable with calibrating, so I do not think that is the issue. Vinny suggested an air bubble too, but I am not seeing one in my line.

Does the ph value drop down while the test is happening? Should be able to watch it go down to under 4.5 then it will give the result.

Are you sure the doser heads are all operating flawlessly and calibrated correctly? No blue chips or sticking.

Have you checked for and removed the tiny inline filter inside?

@Ohashimz nailed it. Not getting enough acid some way? some how.

I am not sure about the filter. Would this involve poping open the top?

I watched the pH value, and it dropped to about 5.62 and then started rising again. So like you guys said, it seems to not be getting enough acid for the test. I have the dosing pump set to a speed of 0. Is this correct?

 

[road_runner]

It is definitely going through the tube. I have had a GHL Doser for years, so I am pretty comfortable with calibrating, so I do not think that is the issue. Vinny suggested an air bubble too, but I am not seeing one in my line.



I am not sure about the filter. Would this involve poping open the top?

I watched the pH value, and it dropped to about 5.62 and then started rising again. So like you guys said, it seems to not be getting enough acid for the test. I have the dosing pump set to a speed of 0. Is this correct?

If you seeing ph drop that means titration is happening for sure...bizzar..
Sorry am not enough help. Will follow hopefully you figure it out. Ghl support is great they will figure it out.

 

[Ditto]

If you open up the unit, and in the GHL app for the KH director diagnostic section if you enable diagnostic and hit the pinch valve do you hear it?

I would pull the tube out from the pinch valve and reseat it into the pinch valve.

Next hit the vent reagent line and see the results foes the reagent flush?

I had a issue with the filter on the Reagent line get clogged you will see air bubbles inside the reagent line to the pinch valve. It may also popped out, i am not sure if they are on the newer units, mine was a first generation run.

The 4 screws are on the bottom, empty the chamber cost before taking it apart. Then leave the cover off and run the test.

 

[Ditto]

Vent the Reagent a few times also and run a test does it say it or does it go off the scale also.

 

[WWIII]

Speed 0 is correct.

@Ditto has the rest covered as far as what you can do to diagnose. When I bought an older khd that someone had sitting around I had to reseat the tubing in the pinch valve as it had stuck itself shut. Once I did that it was fine (past 6 months). Then there is a tiny white filter in the line on the inside of the unit (yes pop the top actually the bottom) check for that and remove it as it's not necessary and not included on the current production units.

I'd do those things with the pinch valve line and check for filter. Then run the other diagnostic tests ditto describes. We can go from there.

 

[Crimsonvice]

Okay, I popped the top and checked the pinch valve. Everything seems to be functioning okay. I do not see an internal filter.

Thoughts?

 

[Crimsonvice]

Well I finally got it to at least measure something. I replaced the reagent 1/4" tube from a stiff orange line to a soft vinyl. Maybe this did the trick. The orange line wasn't clogged or anything, so I don't know what the difference is.

 

[road_runner]

Well I finally got it to at least measure something. I replaced the reagent 1/4" tube from a stiff orange line to a soft vinyl. Maybe this did the trick. The orange line wasn't clogged or anything, so I don't know what the difference is.

Glad it worked out. Still talk to ghl and see what they say and post it here pls so we all learn.

 

[WWIII]

Well I finally got it to at least measure something. I replaced the reagent 1/4" tube from a stiff orange line to a soft vinyl. Maybe this did the trick. The orange line wasn't clogged or anything, so I don't know what the difference is.

Yeah I am stumped. I'm not sure why the rigid ro tubing would make a difference unless somehow it was letting air in and/or losing prime in between tests? Maybe the inside diameter is different, but the dosing head calibration should account for any of that. How many ml/min is the reagent head calibrated to?

 

[kodo28]

I could be wrong but the inline filter is not just next to the connector on your picture ? looks like the filter as drifted to the connector.

This is what look like mine on the connector side

 

[Crimsonvice]

I could be wrong but the inline filter is not just next to the connector on your picture ? looks like the filter as drifted to the connector.

This is what look like mine on the connector side

Ok so that filter is what needs to be removed?

 

[kodo28]

Ok so that filter is what needs to be removed?

Yes it should be removed

White filter in the internal overflow tube not necessary

There is a white filter (approx. 4 mm x 5 mm in size) in the inner venting and overflow tube of the KHD. This filter lets air through but not water. The purpose of this filter is on the one hand, to reduce noise during the measurement from inside the KHD, on the other hand, it should avoid...

forum.aquariumcomputer.com

 

[Vinny@GHLUSA]

As @kodo28 mentioned, that in-line filter should be removed. It looks like it became clogged and could no longer allow air to flow through the tube. After enough tests, that filter will make its way to the end of the vent tube and restrict even more air...ultimately leading to the titration error.

Remove that filter and keep the original internal reagent tube in-place.