Ph Controller advice

[xrayrider]

I am setting up a Calcium Reactor, and I want to use a PH controller, but this is my first Calcium reactor, so I don't know much about them. I have found some Milwakee brand ones pretty cheap. Are they any good? What is the best quality, at the best price when it comes to PH controllers?

 

[AZDesertRat]

I've been using the Milwaukee for about 5 years with zero problems.
Pinpoint is a little better but not worth the difference in price to me, we don't need to control pH to two decimal points for a calcium reactor.
Once it is set up there will be a bit of a learning curve since the pH controller works opposite of how you think it would. I bought a Lees Specimen Container like they use at the LFS to catch and bag fish in and drip my reactor effluent into it. The pH probe is suspended above the container and is set to come on when pH rises and go off when it get low enough.

 

[xrayrider]

Thanks for the Milwakee information. Anyone else have any thoughts to add?

 

[Paul_N]

I have a Milwaukee sms122 with my GEO reactor. The probe goes into the port in the top. It took some playing around when I first set it up but I have not touched it since.

 

[xrayrider]

Is Milwakee the way to go then?

 

[Paul_N]

You can get them for around $100 online. Best bang for your buck. IMO. I have a Pinpoint PH monitor also and cannot see paying $200 for the controller. I got my entire Ca reactor setup used with the Milwaukee controller. If I had to buy new, I would go with Milwaukee. OR you could find a used Reef Keeper or Neptune controller and that would control PH, temp, and more depending on the model.

 

[Acroholic]

The SMS 122 is a great way to go. Just know that you should not follow the instructions that say you only need to calibrate with pH 7 solution. The unit is made for 2 point calibration, which is the only way to have it operate accurately. The hole for the second calibration is on the back of the unit, under a sticker.

 

[xrayrider]

Is this unit a milwakee brand?

 

[Paul_N]

The SMS 122 is a great way to go. Just know that you should not follow the instructions that say you only need to calibrate with pH 7 solution. The unit is made for 2 point calibration, which is the only way to have it operate accurately. The hole for the second calibration is on the back of the unit, under a sticker.

+1 I used both solutions.

Yes the SMS122 is the Milwaukee PH controller.

 

[AZDesertRat]

Calibrate the Milwaukee with a single point as they suggest. There is a reason they say this and you can call them for an explaination. It makes sense when they explain it.

 

[Paul_N]

Calibrate the Milwaukee with a single point as they suggest. There is a reason they say this and you can call them for an explaination. It makes sense when they explain it.

With that being said, would you use the PH7 since you are using it for the Ca reactor and will be monitoring in that range (6.4-7.0)?

 

[AZDesertRat]

Yes, they supply the unit with a starter calibration solution of 7.01 pH.

 

[Acroholic]

Calibrate the Milwaukee with a single point as they suggest. There is a reason they say this and you can call them for an explaination. It makes sense when they explain it.

Show some documentation that shows single point calibration is more accurate then 2 point calibration. It is not.

Single point calibration of a pH controller without calibrating the slope is pure extrapolation (calculating a value outside of one known value), which is never as accurate as interpolation (calculating a value between two known values). Having accurate calibration between two known pH points, pH 7 and pH 10, which is the normal operating range of this controller in reef environment, gives more accurate readings. Ph is not a linear function, it is a slope function. If pH were linear, then one point calibration would be fine, but it is not so one point calibration is insufficient.

Here is quote from the following:

http://www.mbhes.com/ph_meter_guide_care_and_calibration.htm


Two or More Point Calibration


Now that we understand the basics of calibration, why should a meter be calibrated at more than one pH value? Most pH meters should be calibrated at a minimum of two points. The most common points are values of pH 7.01 and 4.01 or 7.01 and 10.01 if you are going to be reading alkaline values. The more advanced Hanna meters will let the user calibrate at three, four or five pH values. These meters will also let the user select which buffers are to be used. While the majority of meters have memorized values of 4.01, 7.01, 10.01 as well as European buffer values (1.68, 6.86, 9.18), custom buffers are available in pH values from 1.00 to 13.00. To achieve the best accuracy, the calibration should cover the range of the desired measurement values. For instance if the user wanted to measure a solution which had values expected to range between 3.00 and 4.00, one would want to calibrate at 3.00 and 7.01 rather than 4.01 and 7.01. This eliminates the uncertainty associated with trying to extrapolate a value beyond the calibrated values. Some very accurate Hanna meters (both bench top and portable) will be able to read and calibrate (using special buffers) to a thousandth of a pH, i.e. 3.204 +/- 0.002 pH. Getting back to the science behind a multi-point calibration requires an understanding of “slopeâ€. Earlier we talked about offset. If the pH values were linear, i.e. a pH value could be calculated by the meter using 59.16mV per pH unit. The meter would display the proper value once the offset error was adjusted by the calibration. However, to make life more complex, the slope of the pH line when plotted (pH vs. mV) may be altered at pH values which vary from pH 7. Hence the error in the reading is larger as the reading increases or decreases from neutrality (pH 7). The good news is that the multi-point calibration also corrects for this deviation. The resulting readings then are correct at all values between the calibration points. If the readings go beyond the calibrated range, the meter assumes linearity and simply extrapolates the value to be displayed. The true value may be slightly different. Much depends upon the users need for accuracy at the measured value and the need for a more advanced meter.

 

[AZDesertRat]

Here is the actual email from Milwaukee on why two point calibration is not needed. I agree for a lab where pH readings may vary, are unknown ahead of time or where slope is critical its not ideal, but a calcium reactor is working in a very narrow pH band or range and what they say makes sense.
" doing a 2 point calibration is call setting the "slope" of a meter or
tester -- in that procedure you do a 7 and then a 4 or 10 and this "points"
the meter at the acid (4) or base ( 10 ) zones of the pH scale -- With a
SMS122 which is almost always used in an aquarium enviroment the " Nutural "
zone ( 5.5 to 8.5 pH ) you want the unit to be most accurate in the neutural
zone and that is why you do a single point calibration at 7.0 "

 

[Acroholic]

Here is the actual email from Milwaukee on why two point calibration is not needed. I agree for a lab where pH readings may vary, are unknown ahead of time or where slope is critical its not ideal, but a calcium reactor is working in a very narrow pH band or range and what they say makes sense.
" doing a 2 point calibration is call setting the "slope" of a meter or
tester -- in that procedure you do a 7 and then a 4 or 10 and this "points"
the meter at the acid (4) or base ( 10 ) zones of the pH scale -- With a
SMS122 which is almost always used in an aquarium enviroment the " Nutural "
zone ( 5.5 to 8.5 pH ) you want the unit to be most accurate in the neutural
zone and that is why you do a single point calibration at 7.0 "

AZDesertRat,
This is not aimed at you, but at the email. That explanation makes no sense. Think about it. The calibration is done at 2 points, between 7 and 10. The pH meter is the same as one point calibration anyways. The pH 10 calibration sets the controller accuracy for reading between 7 and 10. Without 10 you have no way of knowing the accuracy between the the points 7 and 10.

And how on earth can anyone call pH 5.5-8.5 a "Neutral Zone" anyways? 5.5 is pretty acidic, and 8.5 is pretty basic.

Truth is at one point calibration pH 7 it will read fine, but ANY variance off of that without 2 point calibration the error increases the farther away you go from pH7.

I use a Milwaukee SMS 122 for my CA reactor, decent equipment for the price, but they are the only ones I have EVER heard that have said this, even stranger to hear particularly when this piece of equipment HAS 2 point calibration built into it.

Milwaukee Instruments does this for ease of customer use, not for any other reason.

I don't see how it makes sense to anyone. Totally contradicts my understanding of pH Controller calibration and accuracy. And I have not seen any other controller manufacturer ever state the same reasoning.

 

[xrayrider]

Thanks for all the advice, this is the best deal I could find. It is on Ebay. Does anyone know of a better one?SMS122 PH monitor CO2 CONTROLLER sms 122 + FREE CALIB

usa PRIORITY SHIPPING FREE AND FAST- -FREE PH7.0 read YItem number: 260388264069

US $107.90

 

[Acroholic]

Here it is from a well known reef equipment maker, My Reef Creations, for $99. http://www.myreefcreations.com/MRC-SMS-122-Milwaukee-pH-controller

Free shipping from your ebay source probably makes it a moot point pricewise, but I know the owner of MRC, and they have great customer service.
Dave

 

[chadfarmer]

why not spend a little more money and get a controller reefkeeper or aquacontroller jr