I'm having KHD problems...

[SashimiTurtle]

I'm having KHD problems... since day one but I digress.

Issue, KHD takes a few days to detect a change in alkalinity. I did a large 40g water change on my 200gallon total system, and it took 3 days for the KHD to slowly show a rise in alkalinity. I'm not dosing currently so the water change would have been the only change up in alkalinity and it should have been sudden, not over the course of 3 days.

So I decide to go thru and calibrate all dosing heads, re-measure sample line volume with a graduated cylinder and finally go to recalibrate my pH probe, which appeared to be working fine and I could see pH swings when it would take a sample and when it would add reagent. Here, you can see it is reading a pH of 8.12 before and 4.84 at the end of a test. These were taken the day before trying to calibrate the probe.

After calibrating, the pH probe was stuck at 4.84pH and the "ACD1" and "ACD2" were both stuck at 49073. I tried calibrating in RODI, Vinegar, and a soda ash solution. Still stuck at 4.8pH and ACD of 49073 for everything. I figured the pH probe was just old and decided to die when I moved it, so I ordered a new one which arrived today.

I plug it up to the KHD and go thru the calibration process with 4pH and 7pH fluid. I am STILL reading 4.8pH and have an ACD of 49073 on both 1 and 2 with the new probe.

So... what next?

 

[Bfragale]

Do you have another alk tester or test kit? Do you have a PH tester other then that one?

I would use different testers to test both.

I don’t think ph of 4.8 is real. I believe Your coral skeletons would melt at that low of a ph. Calcium reactors run 6.5 and melt coral skeletons. I’m not familiar with your controller but something doesn’t sound right KH should be immediate change and not go up over a few days unless your downing something.

my first thing would be to use different testers and see what they say.

 

[SashimiTurtle]

Do you have another alk tester or test kit? Do you have a PH tester other then that one?

I would use different testers to test both.

I don’t think ph of 4.8 is real. I believe Your coral skeletons would melt at that low of a ph. Calcium reactors run 6.5 and melt coral skeletons. I’m not familiar with your controller but something doesn’t sound right KH should be immediate change and not go up over a few days unless your downing something.

my first thing would be to use different testers and see what they say.

That is the pH in the KH Director sample cell... it uses a 0.1N muriatic acid to basically do a high tech titration test using a pH probe instead of a color changing dye. At the begining of the test it gathers a sample of tank water then slowly adds acid to it to lower the pH. How much acid is needed is then calculated into an alkalinity reading.

 

[Bfragale]

Sounds like an issues with the KH Director. Maybe try to calibrate it again? (If possible)

but I would also test with other test kits and compare.

 

[LOVEROCK]

Are you using the GHL ph 4 and 7 to calibrate

 

[SashimiTurtle]

Are you using the GHL ph 4 and 7 to calibrate

I plug it up to the KHD and go thru the calibration process with 4pH and 7pH fluid. I am STILL reading 4.8pH and have an ACD of 49073 on both 1 and 2 with the new probe.

....