Page 1 of 1
PH Inaccurate
Posted: Sat Jun 07, 2014 1:59 pm
by 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?
Re: PH Inaccurate
Posted: Sat Jun 07, 2014 3:29 pm
by lnevo
Did you record the min and max numbers while you were calibrating?
Re: PH Inaccurate
Posted: Sat Jun 07, 2014 4:10 pm
by Smotz
I didnt. But I can do I t again..
Sent from my SCH-I605 using Tapatalk
Re: PH Inaccurate
Posted: Sun Jun 08, 2014 1:22 pm
by Smotz
lnevo wrote: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?
Re: PH Inaccurate
Posted: Sun Jun 08, 2014 1:23 pm
by lnevo
Tell me what your pH is according to the other tests
Re: PH Inaccurate
Posted: Sun Jun 08, 2014 1:28 pm
by 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?
Re: PH Inaccurate
Posted: Mon Jun 09, 2014 11:10 am
by Smotz
lnevo wrote: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?
Re: PH Inaccurate
Posted: Mon Jun 09, 2014 12:44 pm
by 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.
Re: PH Inaccurate
Posted: Mon Jun 09, 2014 3:21 pm
by Smotz
lnevo wrote: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...
Re: PH Inaccurate
Posted: Mon Jun 09, 2014 4:23 pm
by maineultraclassic
What do the high and low numbers mean?
Is there a recommended range each should be in?
Re: PH Inaccurate
Posted: Mon Jun 09, 2014 4:53 pm
by 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.
Re: PH Inaccurate
Posted: Tue Jun 10, 2014 5:10 pm
by Smotz
are my numbers in the acceptable range?
PH Inaccurate
Posted: Tue Jun 10, 2014 7:21 pm
by lnevo
Yeah very acceptable. sorry man, I forgot about this last night. I'll try and check in a little bit.
Re: PH Inaccurate
Posted: Tue Jun 10, 2014 7:55 pm
by 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.
Re: PH Inaccurate
Posted: Tue Jun 10, 2014 7:58 pm
by 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;
}
Re: PH Inaccurate
Posted: Wed Jun 11, 2014 4:54 am
by Smotz
lnevo wrote: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);
Re: PH Inaccurate
Posted: Wed Jun 11, 2014 9:43 am
by Smotz
Disregard - was syntax. This worked:
ReefAngel.PHMin=614;
ReefAngel.PHMax=860;
Re: PH Inaccurate
Posted: Wed Jun 11, 2014 10:03 am
by 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...