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Discussion Starter · #1 ·
I've been considering a ph controller for a while now, with the Milwaukee SMS 122 seemiing the obvious choice. However, in the specs listed, it's accuracy is reported at +/- .2 degrees. This is a huge swing, and for purpose of maintaining a constant co2 level seems useless. For example, with a target Ph of 30 ppm, and with a kh of 5, the target ph would be 6.7. However, with the quoted resolution on the Milwaukee unit, 6.5 to 6.9 is an acceptable range. This translates to a range of 19-47 ppm CO2, assuming your dissolution techniques are spot on, which, in our applications, they usually are not.

Please, anyone with experience with these units please chime in and give some input. Are the Ph units useful for CO2 regulation, or am I better off dealing with human error.
 

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I can't directly answer your question, but I can tell you that analytical quality is +/- 0.1 unit. If you use a calibration standard you should be able to determine the performance of the meter. A pH 7.00 standard reading 7.02 tells you your meter is reading a bit high and you can adjust from there.

Is the accuracy 0.2 or the units 0.2? Does it read in 0.2 increments or simply is deemed accurate in 0.2 increments? There can be a difference because if it is reading in 0.1 then you can extrapolate more than at 0.2.

Don't know if this really helps or not. But that's all my knowledge right there! :)

Kara
 

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I have been dormant for a while in this hobby. But I've awakened after about two years. I've cleaned out my tank and ripped out all of the weeds and started over.

I've got the SMS-122. The accuracy is well within the normal pH swings that I'd get without C02 injection. Let me explain. When I had a lot of plants with 2wpg + sunlight, the pH would swing up during the day, and drop at night. This swing was well beyond +- .2, and I would guess that the dissolved CO2 varied much more than the range you indicated.

This range in accuracy, although wide, does not mean that the pH will swing this much. It means that the error in your reading will generally be within that range. If you calibrate it with a 7.0 buffered solution, and the meter says 7.0, you can expect it to stray off a little in either direction, due to temperature, or whatever other factors may creep in. I'm guessing that this deviation will not waver back and forth, but remain relatively constant over time. So you will have a relatively constant pH over time.

I have had no problems with pH using this controller. When I tried diy natural CO2, I ended up with a fizzing aquarium after the first day. I no longer worry about the pH. And the plants are happy.
 

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Not an expert here, but a thought...

+/- 0.2 doesn't necessarily mean it swings that way all the time. I think it means that if your water has a pH of 6.7, the controller might read it as 6.5, spot on, or 6.9, and is still in spec. You should verify with a higher precision method where it REALLY is and go from there.

Edit: Ooops, got ninja'd big time. :tongue:
 

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Discussion Starter · #5 ·
Accuracy is ±0.2 pH, resolution is ±0.1 pH. To me this means that natural conditions in the tank (CO2 utilization/saturation, photoperiod, photosynthesis etc) can (and in my experience, most likely often will) cause pH to fluctuate. If this happens within a range that is undetectable by the equipment, while still having a significant impact on CO2 levels, then there's a problem.

I already have a pressurized system, so I have some level of control over C02 rate, but I really like the idea of "set and forget".

So what you're saying is that the calibration standards are used to pinpoint the direction of inaccuracy in the unit, either upward or down, and get a better idea of where the pH may actually be in relationship to the meter's reading?

Thanks helping me out with this one guys, I appreciate it.
 

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I used to have a milwaukee sms122 but changed to a pinpoint controller.I like the pinpoint controller much better, Imo it's a little more acurate (.01 vs .1) but costs twice as much.
 

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You are talking about the pH to KH chart?

An easier way to figure it out is to take a sample of water and let it sit out for 24 hours to outgas. Take a pH reading. This allows the water to achieve and equilibrium with the atmospheric CO2. You should now be at 3-4 ppm of CO2.
Take the pH reading that you get and reduce it by 1 pH and you should be at 30ppm CO2. So in all actuality that .2 degree accuracy doesn't add up to as much as the chart shows.

That being said I have the same controller and using the same method this is what I have found to work the best.

You set the controller to 1 pH less than your out gassed sample.
Run you CO2 regulator/solenoid on a timer.
Start the solenoid an hour before lights on, and have it turn off an hour before lights out. (Depending on the size of your tank you could opt for a half hour on each end)
No fish gasping at the surface (besides new additions)

You will also need to get 2 calibration fluids. 7.01 AND 4.01 to calibrate the meter. There are two screw holes one on teh front and one on the back to make the adjustments. The controller reacts after a .2 pH drop.

Hope that helps
Lou
 

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I used to have a milwaukee sms122 but changed to a pinpoint controller.I like the pinpoint controller much better, Imo it's a little more acurate (.01 vs .1) but costs twice as much.
I might be thinking of the wrong model here, but when I was looking for a pH controller, the current model from Milwaukee also didn't do 2 point calibration like the Pinpoints do, for the added accuracy.

Jon
 

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i've never felt that the strong point of the controller was maintaining an extremely precise range of pH or CO2 concentration. it would require way too much work, calibration, and expense even with a higher end unit. if your plants are currently doing great and you have a nice metering or needle valve setup to give consistent rates, then you probably don't need one.

i can think of a couple of the benefits of having closed-loop control... you can get away with having a cheaper regulator/needle valve setup (fine tuning is not required). you can reduce CO2 usage, which means fewer trips for refills. having a real-time display helps reduce continual pH testing. as i see it, anything that helps me reduce the amount of time maintaining the tank is a 'good thing'. gawd, i just got a weird image of martha stewart in a prison outfit just now. heh
-snafu
 

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I might be thinking of the wrong model here, but when I was looking for a pH controller, the current model from Milwaukee also didn't do 2 point calibration like the Pinpoints do, for the added accuracy.

Jon
You can do a two point calibration with the SMS 122. But, there's an extra set of directions that comes with the unit. It says that for normal aquarium use to only use the 7.01 pH solution to calibrate it to a pH of 7.0.
http://www.milwaukeetesters.com/
 

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I might be thinking of the wrong model here, but when I was looking for a pH controller, the current model from Milwaukee also didn't do 2 point calibration like the Pinpoints do, for the added accuracy.

Jon
Milwaukee can do 2 point calibration but thats not what I was talking about. IMO the pinpoint would be more acurate because. Pinpoint readout 7.01 and Milwaukee readout 7.0. The pinpoint will come on after .1swing while the sms122 will come on after .2. I don't think the difference is that critical!
 

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I'm coming full circle on my opinion on using a controler. I use to use one, then stopped and only used it for a pH meter. Just recently I put it back on one of my tanks controling the gas. Reason? I do a water change every night automatically - about 12% and the pH will raise a lot as we now have harder water out of the tap do to an acid nuetralizer we had to install in a well house. My tap water was so acidic that it was making pinholes in copper tubing near the hot water heater hot line. Now the tap raises to 7.8 sitting, and thats with a major bypass of this acid nuetralizer. If it was straight, it might be near 10 pH.

So my pH was going from 6.5 or so daytime back up to 7.2 during the night after this water change. By putting the controler back on, the pH can be back at 6.4 or so in a few hours and its keeping it more constant. Probably better for controling BBA and for the fish in general. Maybe its a unique situation, but I think in this case its probably a better solution for me...
 

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I am looking into possibly getting a aquacontroller for automation and a side effect would be the ability to use it as a ph controller for my co2. I am undecided though. One of my concerns is overnight... what do you all with controller do overnight? if you want to promote more O2 at night by some extra surface agitation, and off gas some co2, wont the controller just try and dump extra co2 back in the system?

And the other concern is about KH. This is a pH controller, not a co2 controller, so I assume it rely's on the pH/KH relationship to effectively become a co2 controller. Well what if your KH from you tap varies? If you have autowater change going on and one day your tap KH happens to come out at 8* instead of 2* what will happen... your controller dumping mass quantities of co2 in trying to drop the pH several points? I dont know if this is much to worry about, but the thought kind of scares me a little.
 

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One of my concerns is overnight... what do you all with controller do overnight? if you want to promote more O2 at night by some extra surface agitation, and off gas some co2, wont the controller just try and dump extra co2 back in the system?
Yes but you could hook up the controller to a timer and the aquacontroller jr may let you determine when the controller function is working and when it is not, like a timer would do.
And the other concern is about KH. This is a pH controller, not a co2 controller, so I assume it rely's on the pH/KH relationship to effectively become a co2 controller.
Actually it's called a controller because it can power something based on a pH setpoint. You could make it turn on a lamp when the pH changed if you wanted to and then it would be a lamp controller not a pH controller. So if it is hooked up to CO2 it becomes a CO2 controller
Well what if your KH from you tap varies? If you have autowater change going on and one day your tap KH happens to come out at 8* instead of 2* what will happen... your controller dumping mass quantities of co2 in trying to drop the pH several points? I dont know if this is much to worry about, but the thought kind of scares me a little.
A definite possibility but not very probable on a city water system as they keep things like that under fairly good control. I've had many different systems in many different cities in many different states and I've never seen that large of a fluctuation.

Brian
 

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One of my concerns is overnight... what do you all with controller do overnight? if you want to promote more O2 at night by some extra surface agitation, and off gas some co2, wont the controller just try and dump extra co2 back in the system?
I agree with everything Briandnmiles said. On the extra gas at night, two things to consider. BBA is said to like changes in CO2 concentrations. By leaving on all night, the pH and CO2 level stays more constant, which IMO is a good thing. Other thing to consider is gas is cheap and the little bit of CO2 put in during the night will be fine as long as one has decent top current on an open top tank.
 

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I agree with everything Briandnmiles said. On the extra gas at night, two things to consider. BBA is said to like changes in CO2 concentrations. By leaving on all night, the pH and CO2 level stays more constant, which IMO is a good thing. Other thing to consider is gas is cheap and the little bit of CO2 put in during the night will be fine as long as one has decent top current on an open top tank.
I'm not worried about the cost of co2, I was concerned with the diminishing O2 levels at night, especially with loaches. Riding myself of BBA would be nice though - I dont have problems with it growing bushy anymore but still black coloring on some leaves which I assume is still BBA just not as bad?

I wonder for O2 loving fish with a controller, if perhaps injecting pure O2 like Tom has done before would help maintain levels at night? Maybe then I could bring back rainbowfish into the picture - I had some problems with them in the past.
Yes but you could hook up the controller to a timer and the aquacontroller jr may let you determine when the controller function is working and when it is not, like a timer would do.

Actually it's called a controller because it can power something based on a pH setpoint. You could make it turn on a lamp when the pH changed if you wanted to and then it would be a lamp controller not a pH controller. So if it is hooked up to CO2 it becomes a CO2 controller
I'll have to figure out if this feature can be set on/off on a timer. About the term controller, what I was simply getting at is that it doesnt control a device (whatever that may be) by co2 levels, it controls based off pH levels. And I have always been suspicious of the various things other than co2 that can fluctuate and change those levels. I really like the set and forget method and to not have to worry about those darn test kits anymore. I am just worried trying to use a controller I'll have to start continuously monitoring things like KH, and probably have to mess around calibrating probes - although thats not to often I suppose. How often do you have to calibrate the probes? Probably a simple drop checker and the occasional glance would set my mind at ease its not dumping to much co2 in. I'll have to invest in individual solenoids though, since I'll be running centralized co2 once I get the new tanks up and runnin.

Thanks guys for the help, got some things to consider.
 

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I have the milwaukee, and no-it is not the most accurate. Seems to READ the ph ok, but it doesn't always turn on and off appropriately. that said, it doesn't seem to be a big issue as long as your not keeping extremely delicate fish. i've had fine luck with it so far.
 
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