PH calibration

Basic / Standard Reef Angel hardware
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rwijbenga
Posts: 16
Joined: Thu Aug 11, 2011 11:00 am
Location: Netherlands

Re: PH calibration

Post by rwijbenga »

Here are the numbers..

PH4 217
PH7 512

Hopefully you can show me how to calculate the PH10 number from this.

Remco
rimai
Posts: 12881
Joined: Fri Mar 18, 2011 6:47 pm

Re: PH calibration

Post by rimai »

http://en.wikipedia.org/wiki/Linear_interpolation
Let's say that x axis is pH and y axis is the raw numbers.
We know the following:
x0=4
y0=217
x1=7
y1=512
So, the formula would be:
y=217+((x-4)*((512-217)/(7-4)))

We want to interpolate and find the y value for when x=10
y=217+((10-4)*((512-217)/(7-4)))
y=807

So, in your case, you can use PHMin=512 and PHMax=807
Just place these lines just below the ReefAngel.Init() function:

Code: Select all

ReefAngel.PHMin=512;
ReefAngel.PHMax=807;
Let me know if it got too confusing.
Roberto.
rimai
Posts: 12881
Joined: Fri Mar 18, 2011 6:47 pm

Re: PH calibration

Post by rimai »

An easier way for the future, for those that don't want to bother with the math part of it.
Just take the difference between pH7 and pH4, add it to pH7 and you've got your pH10 number.
512-217=295
512+295=807
807 is your number to be used for PHMax.
PHMin is always the same as pH7 raw number reading.
Roberto.
rwijbenga
Posts: 16
Joined: Thu Aug 11, 2011 11:00 am
Location: Netherlands

Re: PH calibration

Post by rwijbenga »

Thnx for all the info ! :)

I also have tested changing the PH.Params map. That worked also without a problem. :)

So now I have 2 way's of using PH4 calibration fluid.
rimai
Posts: 12881
Joined: Fri Mar 18, 2011 6:47 pm

Re: PH calibration

Post by rimai »

Just remember that the changes in the map function inside the library will get overwriten by any update that Curt releases on the libraries and you will need to change it again.
Roberto.
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