PH Inaccurate

[Smotz]

Hi all,

My PH is reading 8.6 - which I know is inaccurate by testing with test kits. I am ordering another PH tester just to be sure.

I have already replaced my probe and recalibrated.

Is there any manual adjustment I can do?

[lnevo]

Did you record the min and max numbers while you were calibrating?

[Smotz]

I didnt. But I can do I t again..

Sent from my SCH-I605 using Tapatalk

[Smotz]

Did you record the min and max numbers while you were calibrating?

Just recalibrated again

min (7) = 554
max (10) = 802

Ph is currently reading 8.86 which I KNOW is reading high according to API tests.

Got any direction?

[lnevo]

Tell me what your pH is according to the other tests

[Smotz]

the api test with the color codes say ~ 8.2.

I got a digital PH reader coming on Tuesday to be absolutely positive.

On a side note - I noticed that your Salinity is measuring 0 - you don't measure salinity?

[Smotz]

Tell me what your pH is according to the other tests

I have confirmed that my PH is a perfect 8.14

Any way to manually adjust the PH on the RA to reflect that?

[lnevo]

Yes. I have a script at home I have to play with that will help me come up with some new variables to update the calibration fields. I did it myself to work around stray voltage from my skimmer to get a more accurate number. Sorry I was obtuse in answering, but I needed to get the details in order to move forward.

One thing I would recommend checking before looking to fudge the number is check through the wifi to see what values were recorded in memory for PHMin and PHMax since the sensor can jump around but since the screen redraws every few seconds, you may not see and that could be the number that get's recorded... just something to look at as it happened to me. But unlikely if you recalibrated when re-checking and still have same result.

[Smotz]

Yes. I have a script at home I have to play with that will help me come up with some new variables to update the calibration fields. I did it myself to work around stray voltage from my skimmer to get a more accurate number. Sorry I was obtuse in answering, but I needed to get the details in order to move forward.

One thing I would recommend checking before looking to fudge the number is check through the wifi to see what values were recorded in memory for PHMin and PHMax since the sensor can jump around but since the screen redraws every few seconds, you may not see and that could be the number that get's recorded... just something to look at as it happened to me. But unlikely if you recalibrated when re-checking and still have same result.

You're a good man, Lee. I'll wait for your magic...

[maineultraclassic]

What do the high and low numbers mean?

Is there a recommended range each should be in?

[lnevo]

It's the voltage returned by the probe. It varies slightly for each probe. The numbers are used with the map command to convert it to a value between 7 and 10.

[Smotz]

are my numbers in the acceptable range?

[lnevo]

Yeah very acceptable. sorry man, I forgot about this last night. I'll try and check in a little bit.

[lnevo]

Change your phMin to 614 and your phMax to 860

You can use the PHMin_write(const int value) and PHMax_write(const int value) functons or use the wifi /miX,Y (PHMax - 231 and PHMix - 233) to update the fields. You will need to reboot for it to take affect /boot if you're on latest libraries.

[lnevo]

Here's the map function that's used to map the phmin and phmax variables to 7 and 10 so it returns the adjusted ph to our measure. It's simple math to play around with the numbers.

Code: Select all

long map(long x, long in_min, long in_max, long out_min, long out_max)
{
  return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
}

[Smotz]

Here's the map function that's used to map the phmin and phmax variables to 7 and 10 so it returns the adjusted ph to our measure. It's simple math to play around with the numbers.

Code: Select all

long map(long x, long in_min, long in_max, long out_min, long out_max)
{
  return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
}

I get this error - I have the latest code - actually, I have the Devs running.. Any thoughts?

Display_Tank_test.cpp: In function 'void setup()':
Display_Tank_test:72: error: 'class ReefAngelClass' has no member named 'PHMin_write'
Display_Tank_test:73: error: 'class ReefAngelClass' has no member named 'PHMax_write'

when I put:

Code: Select all

ReefAngel.PHMin_write(614);
ReefAngel.PHMax_write(860);

[Smotz]

Disregard - was syntax. This worked:

ReefAngel.PHMin=614;
ReefAngel.PHMax=860;

[lnevo]

The commands should have been InternalMemory.PHMin_write()

The only issue hard coding it the way you did is that you can't recalibrate Although you may not want to...