Calcium Reactors....

So I decided to hook up that reactor setup I was trying to sell. I'm running ARM in it at the moment.  I'm running the feed pump and c02 solenoid off my Apex. My total water volume is about 100 gallons....
The following is based on the pH inside the reactor....
For feed pump outlet
Fallback OFF
If pH > 06.89 Then OFF
If pH < 06.51 Then ON
For c02 solenoid
Fallback OFF
If pH > 06.89 Then ON
If pH < 06.51 Then OFF
This seems to be keeping the pH in my tank between 8.15 and 8.25.
Question 1, how slow or fast do I want the transition from low pH to high pH to be? Right now I have it set to about 1 bubble per second of c02. I have not measured my effluent output yet. The way it sits now it takes about 30 - 40 minutes for the pH in the reactor to drop from 6.90 to 6.50, and about 15 minutes to go from 6.50 to 6.90. Is that too fast or too slow? Should I let the pH in the reactor get below 6.50?
Question 2, those of you running calcium reactors, what do you when your lights are not on?

 

FYI You don't have to cycle the reactor pump on and off.

The transition from high to low should take about 30-40minutes. Going from 6.5 to 6.9 in just 15 minutes is a little fast, you may want to turn down the flow rate. Of course when you turn down the flow rate, it also will take a little longer to go from 6.9-6.9 but that's okay. Ultimately your dKh will dictate what your flow rate is. I control my CO2 from 7.0-6.8 and keep a slightly lower flow rate.

Q2: I run my 24 hours a day, when your dKh is between 8-10dKh your pH will stabilize (albeit low 7.9-8.0) most people consider this to be perfectly acceptable. Personally though, I combat low pH with the use of a kalkwasser reactor. You can also use Seachem reef builder or reef buffer (one of them raises the pH without raising the dKh).

 

Hmm, it was my understanding that the ARM does not start to break down until the pH in the reactor hits 6.5 or below. Do I not need to let the pH get that low? I have never used a calcium reactor on my setup before, so all I know is what I have read online : ).

After reading this I slowed the c02 down a tad and decreased the flow for the feed pump.

Another question, is it ok to cycle the stir pump (not the feed pump) on the reactor, say run for 5 minutes, off for 15 minutes etc?

 

Yeah, I run ARM too, and I seem to maintain good dKH even with a mild 6.8 acidification. As long as the effluent is slightly acidic there's no reason it shouldn't break down any calcium carbonate in the media. However, that makes me question the dissolution of other components concentrated in ARM, perhaps other beneficial components such as strontium have a lower Keq. That would explain why some of my colonies are quite brittle. You have to assume that if ARM is made of dead old coral skeletons taken from the ocean, then all of the constitutive components in their composition have to beneficial to dissolve into our aquarium water.
I don't see how (functionally speaking) it would be problematic to cycle the stir pump on and off, however I don't see how it would be beneficial either other than shaving a measly 1.5Kw/mnth off of your energy bill (if that). However, I would heed caution that cycling any A/C device on and off and on and off is very hard on the motor and could reduce it's life span.

 

Yes, try to keep the pH low enough to dissolve the media in the reactor.

Your recirculating pump should remain on all the time so that it distributes CO2 evenly throughout the reactor. Plus I guarantee you will have startup problems with your pump (cycling on and off) because calcium will build up quckly in the housing and impeller. Keep it on, it's ok. /DesktopModules/ActiveForums/themes/_default//emoticons/smile.gif

 

Thank you both for the great information, it is appreciated!! : )