Milwaukee PH controller / CO2 regulator question

[eleyan]

This is a questions for you Calcuim reactor folks. I'm looking at buying a Milwaukee co2 regulator with a solenoid shut off valve and a SMS 122 Milwaukee Co2 PH Controller combo to use with a Ca ractor. My understanding is that I would have the solinoid shut off CO2 if PH drops too low in the main tank. However, the discription on the Milwaukee controller on some sellers site says "Alarm Active when reading is higher than set PH point" . On a different site it says that alarm active when PH is lower than set point. Which one its it? Is this used in a different setup than the Ca reactor? is it used to inject CO2 into the main tank in case PH gets too high to lower it down? does anyone have one of these controllers that can shed some light on this?

Thanks

[matt]

I don't know much about these, but I'm sure you want to set it up so that it shuts off CO2 flow to the reactor in the event of low tank ph. Whether or not doing this will actually raise the tank ph, and how quickly, is another story. Basically, lets say your tank ph falls below what you want it to be, then you shut off flow to the reactor. But, you're still sending low ph effluent from the reactor into the tank, probably for several hours, because the reactor ph will not rise immediately from the shut off CO2. And, as your reactor ph rises, the alkalinity of the effluent will drop dramatically, leaving your tank more vulnerable to ph swings.

I think the solution is to set up your reactor so that CO2 cannot be introduced directly into the sump; you can do this by 1)making sure your effluent drips through the air before it hits the sump, and 2) making sure your CO2 flow to the reactor is steady, by using a regulator with a high quality needle valve, or better, a dywer flowmeter to regulate CO2 flow. Also, your reactor design will have something to do with this. My reactors, for example, are pretty sizable and can handle a pretty big spike in CO2 flow without passing any on to the tank. The most important use for a solenoid control is in the event of a power outage; in that case CO2 flow is shut down to the reactor whenever the power goes out and your reactor is not circulating. That prevents a build up of CO2 in the reactor, which would then get sent to the tank when the power comes back on.

[Markster]

I have this exact combo. It is a little confusing at first on the alarm sensor. I have the set point at 7.6 and that means the alarm is on, allowing the soleniod to be open and CO2 flowing to the reactor. The pH monitor shows 8.0 mostly so the alarm will always be on. When I collect some of the drip water and check the pH with the monitor, it drops to 6.7 and the alarm turns off thus shutting the CO2 into the reactor. Once I place the probe back into the sump and the pH increases to 8.0, the alarm kicks on and CO2 flows.

[eleyan]

Thanks for the info.
Markster, So the alarm is always on in normal operation. Its when the alarm turns off that the CO2 flow shuts off .. pretty counter intuitive. Is the alarm audible or is it just flashing the screen?

Thanks,

[Markster]

The alarm is just a flashing red light. There is no audibles and yes it is counter intuitive and took me a little while to adjust (reverse logic)!

It works great and I am glad it was the one I purchased.