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Re: [APD] Milwaukee controller and testing of CO2

After 10 years of no CO2 controller life, I finally acquire mine past July. 
Since then, life?s easier. To know what?s up with PH level I just take a 
glance to the MS 122 display.

I can look for an industrial PH controller with a greater precision, but I 
think is a matter of solving a problem with the minimum resources.

The hysteresis of my system round 0.1.  If values are changing more 
radically there?s an other issue, such as too much gas getting to tank, 
without the sufficient time to equalize the average value, or the probe is 
to far from the reactor/difusser. This type of controllers (on/off) enhanced 
they hysteresis when the error signal is getting earlier to the decision 
circuit. This is done by slowing down the process or by getting actual 
values asap.


>From: Thomas Barr <tcbiii at yahoo_com>
>Reply-To: aquatic plants digest <aquatic-plants at actwin_com>
>To: aquatic-plants at actwin_com
>Subject: [APD] Milwaukee controller and testing of CO2
>Date: Wed, 28 Sep 2005 09:04:09 -0700 (PDT)
>I recently came back from a meeting where several members had these.
>Every single tank had CO2 issues.
>I did not reralize that these cheaper controllers ONLY have 1 decimal point 
>of measurement.
>I do not own one. This means that the controllers can only hope to hit 
>0.2pH units at best and more like 0.3 pH.Even with that added accuracy, 
>folks still have a 0.2pH unit float range. Reducing that means an even 
>larger range of control betweeen the set values(0.3-0.4pH units). Note, 
>this is what some folks have told me, I've seen them and have not used one. 
>Yes, you can still have a nice tank with one etc, I can grow a tank without 
>measuring either pH/KH and use CO2 also but I have the experience to do so 
>as do a number of folks.
>When it comes to accuracy using a control function, more is better but some 
>practical issues do come into play(cost). CO2 is the most important level 
>to monitor and control and also one of the widest with errors of margin.
>The few $ for more accuracy is well worth it.
>Controller schmonollers.
>I've used them, can afford either and even then some, and I know as 
>aquarist they are a long way from being needed. I'd rathwer have 7.00 
>instead of 7.0 accuracy for the 10$ difference and have no control function 
>at all.
>That control function is no better than a needle valve in practical terms.
>So you do not gain something from it.
>Setting up the control function also means you need to add more CO2 than is 
>really needed, some folks are wise and add just  hair more so the pH 
>controller is running most of the time "ON", some folks set it at a higher 
>rate and it cranks in lots of CO2 and then shuts ON/OFF often. This is more 
>dangerous and provides less stable CO2 levels if you graph the levels 
>during the day(I have a graphing function on monitors/controllers at work 
>and on a client tank).
>If you set it just above the needed amout anyway, why even use the control 
>I'd much rather have a pH moniter(or a controller) than is more accurate. 
>While KH measurements might be less than accurate(see past post), getting 
>better handle of CO2 is still critical given the importance of CO2 in our 
>You get what you pay for, I think the cost is not worth it in this case. 
>Several folks have had more issues in the use IME/IMO.
>I'd personally opt for the pinpoint monitor and a good alkalinity test kit 
>anyday. Even this levels of accuracy is often still not enough for 
>obtaining good non limiting CO2 levels in most of our tanks.
>More time to calibrate? That takes about 30 seconds. Place the probe in the 
>calibrate solution at 4.00pH, dial it in, rinse well before and after with 
>DI water, add to the pH solution at 7.00pH, set and you are done.
>But if you use a test method/kit, and rely on it, a little better accuracy 
>is worth the little extra $$, we have found this to be true with other 
>cheapy test kits in the past and I still suggest Lamott/Hach test kits, but 
>some can get by with cheapies + calibrating them(Do not assume someone 
>else's test kit, or some cheapy brand is going to the be the same as 
>someone else's, calibrate them individually yourself!!!).
>Can you do it with a controller? Yep, without? Yep. Without the added 
>decimal place? Yep, but I'd still rather have a monitor function and 
>another level of accuracy higher for only a few $ more.
>If you are really cheap, do not use the controller at all, rather use an 
>accurate test kit, 4-10$ will get a narrow range (0.2pH units) test kit and 
>a KH kit, set it and eyeball the rest by watching fish/plants. This is an 
>upper price range item that has trade offs from what I've seen.
>So if cost is really a concern, then test kits are good. Otherwise I'd get 
>a nice pH monitor so you can use it on many tanks, rather than needing 3 pH 
>controllers for all three tanks. Just use a good pH monitor and adjust the 
>valve up/down as needed. The control function is really something we do not 
>need, although many new folks are sold on it as a convenience issue.
>Watching the pH/KH is something folks will not want to be complacent about.
>Stray current (ballast from lights etc) does affect pH readings also. If 
>you set ehte CO2 rate using the monitor and turn the equipment off to do 
>so, then this issue is resolved.
>There are a number of issues when determining the pH/KH on a planted tank 
>and many folks have CO2 issues IME/IMO, far more than any single issue.
>At the end of the day, the plants/algae(BBA) should be the ultimate test.
>Add more CO2 till you no longer see any positive plant growth response(or 
>add so much the fish are being affected) while maintaining good nutrient 
>Even the best test kits do not tell you what you need to know as an 
>aquarist, but they will get you close, then you take the step of faith and 
>add more CO2 till you get the growth/reduced algae and watch the fish 
>Tom Barr
>Yahoo! for Good
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