Apex and Calc reactor


New member
I got a great deal on a calcium reactor and am going to set it up to be run by my Apex.

I was told that when you use a controller the bubble rate doesn't matter much because the controller will control the solenoid to control the ph rather than the bubble counter. Does this sound right? The unit I got is a reef octopus 2 chamber with a holder for the ph probe.
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New member
Once you get it set up, verify that the solenoid operates correctly if you place it on one of the triac outlets (1-3, 5-7). Those outlets have issues turning off when using low current devices. If it does have an issue, then use either outlet 4 or 8.



New member
I am working on a little project to do just such, but I would not recommend using the CO2 solenoid, not designed for this purpose. Use a electronic valve from Clippard ~ $30.00 this is exactly what they are designed for, billions of cycles.


In my project will be using the Variable port to sent a 5v (50%) output to some components to switch the valve on and off. For those familiar with basic electronics, there is numerous ways to do this, opto-isolater, transistor etc. The output of the Apex can only support 10ma so don't try and drive the valve directly.

Would conrtol the on and off times of the valve, say OFF for 10 seconds and On for 1 second. May use the divide by 10 if I want to fine tune.

I believe the valve is also available in 120vac so you could use the EE8, but likely it would not have enough current to turn off the Triac, if you used the relay it would not last very long with all the switching, as well the control would not be as fine if using the Variable Speed.

The co2 solenoid would be used in the event the valve should somehow fail shutting off the CO2 if the ph of the reactor dropped too far.

Will post detail when I receive the valve and get it tested.



New member
I was told that when you use a controller the bubble rate doesn't matter much because the controller will control the solenoid to control the ph rather than the bubble counter. Does this sound right?
I believe that is a bit simplistic. Yes, you can use the CO2 solenoid as the primary means of controlling CO2 (leaving the needle valve wide open), but the better approach IMO is to use the needle valve/bubble counter as the primary means of managing CO2 addition, using the solenoid only for shutoff of CO2 in event of power loss or if effluent pH gets too low. You will still need fine tune the reactor to ideal operations (or at least close to that), as Ken mentioned, which is a bit of a PITA, but worth the effort IMO. If the CO2 rate is fine-tuned, then the solenoid won't be activating and deactivating as frequently. Consequently, this approach reduces the likelihood of solenoid failure


New member
Here is what I have been doing for the last several years with good success. I have determined that 150ml per minute is the correct flow rate for my setup so I calibrate my water flow needle valve to provide 150ml per minute flow (your flow may vary and really depends on the calcium load of your system). I set the bubble rate to a point where the pH in the reactor can drop to my lower setpoint in 10-15 minutes. When the lower pH setpoint is reached, the CO2 solenoid shuts off (mine works fine on a Triac outlet). Over the next 25-35 minutes or so, as tank water is pumped through the reactor, the pH graduly raises to the upper set point and the CO2 is turned on again. This results in a cycle time of about 40-50 minutes. This allows me to set an alarm that goes off if the cycle time EXCEEDS 60 minutes which indicates reduced flow through the reactor (clogged water flow needle valve) and it is time to clean the needle valve (you can see an example of an extended cycle time on the right side of the attached graph).

Do not open the needle valve all the way as it will typically dump too much CO2 in the reactor and either cavitate your circulation pump or cause excess CO2 to gather at the top of your reactor.

Adjust the pH up or down in the reactor to administer more CA (lower pH range) or less CA (higher pH range). I typically have .3 pH between the on point and the off point.


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