What should Calcium reactor output measure?

[gkyle]

I've read the many fine papers, but I still can't find what a balanced output should look like. The tuning possibilities have me running in circles.

I measured my reactor effluent today using fairly new Elos kits, and I have the following numbers:

pH = 6.45 (Neptune probe)
dKH = 23 (is this possible?)
Ca = 525

I can't actually count the effluent drops, but it is just less than a steady stream - maybe 120-150/min. I use a Pinpoint controller on the reactor, which is a GEO 624 with ARM media.

My tank at this same time measures 8.08 pH, 425 Ca, 9 dKH. My pH tends to run low so I'd like to keep the alkalinity a bit closer to 11. Specific gravity at the time of this test was 1.024 with a refractometer just calibrated with 53 fluid.

Thanks

 

[Randy Holmes-Farley]

23 dKH is certainly possible. Some folks have it as high as 40 dKH in the effluent. I'd track the effluent by alkalinity since it rises a lot while calcium does not rise much in the effluent, relative to what was in the input water.

FWIW, you are not balancing anything in the effluent, and in fact have no control over the relative amounts of calcium and alkalinity added. All you have control over is the amount of CaCO3 dissolved, and that boosts both. If the reactor is maintaining adequate alkalinity, it is also maintaining adequate calcium. If you need a bit more of both, then adding a bit more CO2 is a likely way.

These may help:

Calcium Reactor setup calculator
http://home.comcast.net/~jdieck1/reactor.html

A Guide to Using Calcium Reactors
http://www.reefkeeping.com/issues/2002-05/sh/feature/index.php

If you want to raise the pH, you are probably better off bringing in more fresh air or using limewater in addition to the reactor. As long as you are not using excessive CO2 in the reactor, then tweaking it to get pH effects is not all that productive. This article may help:


Low pH: Causes and Cures
http://reefkeeping.com/issues/2004-09/rhf/index.htm

 

[gkyle]

Thank you for the response. I think I get confused about the relationship between the reactor's internal pH and the effluent drip rate. It seems that you can accomplish the goal equally well with a slow drip but a higher internal pH, or you can use a fast drip with more CO2 to dissolve the media more quickly? If both methods yield the same result, less CO2 is certainly preferable.

My latest adjustment was two weeks ago when I noticed that my Ca and alkalinity numbers were dropping, even with the fast drip rate. I lowered the pH setting on my controller to 6.5 (down from 6.6) and the numbers improved. I was concerned that the lower pH would cause the media to melt too fast though, and also my current approach uses fairly constant CO2 injection at a rate of 10-12bpm.

I do use a Kalk reactor for my top-off and blow a strong fan to increase evaporation. I also plumbed the reactor output into the intake for my recirculating skimmer. That seemed to help.

Thanks again!

 

[Randy Holmes-Farley]

It is possible to optimize both the flow rate and the CO2 addition rate for any given demand (within reason), and that is largely done by trial and error.

I personally would not control it by pH, but rather the observed CO2 addition rate. pH calibration drift will impact your reactor functioning if you use a controller.

 

[Rouselb]

Randy, are you saying that once you get your Ca and KH stable, you should not use a PH controller to keep the PH in the reactor at a certain level?

 

[Randy Holmes-Farley]

That is correct that I would not do that. Some people do, but I'd rather control it by the CO2 needle valve.

 

[Rouselb]

I have read that many people do not use a controller. And that once you dial it in (KH to be constant), you should be good to go without using a controller to turn the CO2 on and off. I think i will try that, just unplug the controller and use it as a monitor. Thanks for the input. One other question, once you have the KH stable, can you cut back on the amount of Lime water that you use? My PH is real stable, does not change much, i have a 75 fuge.

 

[Freed]

I have been keeping an eye on my alk and calcium levels in my tank. If they are a bit low, I bump the CO2 up a bit by dropping the pH target with my controller. Too high, I drop the CO2 a bit.

 

[gkyle]

Interesting advice, I don't think I would have considered that before. I have found that at times the internal pH is really low because the solenoid doesn't close for whatever reason, and I've simply adjusted the bubble count to get it close. I'll try running without it, would be nice to have one less controller I need to worry about and calibrate.

Thanks for the advice.

 

[Randy Holmes-Farley]

You're welcome.

Good luck.

can you cut back on the amount of Lime water that you use? My PH is real stable,

Yes. If the CaCO3/CO2 reactor maintains adequate alkalinity, and the pH is OK, there is little additional benefit from the limewater.

 

[pdelcast]

I don't rely on a controller to maintain PH -- I use the needle valve to do that.

BUT -- I do set the controller to shut off the CO2 if the PH of the tank drops below a "minimum allowable" level (7.7)

Never actually had the controller shut down the CO2 (my tank stays fairly constant 8.2PH.) But the controller is there just in case of a hardware failure of some sort that lowers the PH.

 

[kwgozy]

<a href=showthread.php?s=&postid=12774731#post12774731 target=_blank>Originally posted</a> by Randy Holmes-Farley
That is correct that I would not do that. Some people do, but I'd rather control it by the CO2 needle valve.

Might sound a little stupid. I have calcium reactor that not yet set up. I have a electronic seloniod for my Co2 tank. So you are saying once you find the spot on your needle valve that is producing the results you are looking for that will always be the idea target reading? I have not yet bought a controller and if that is the case I could just borrow one until I get everything dialed in correctly. Then return it.

Thanks,

Kyle

 

[kwgozy]

another one, what is kh

 

[Randy Holmes-Farley]

So you are saying once you find the spot on your needle valve that is producing the results you are looking for that will always be the idea target reading?

Pretty much. It may need occasional tweaking, but a controller will not change that need, and in fact may make it more necessary or impossible to accomplish as the pH calibration drifts.

another one, what is kh

KH or dKH is the german term for alkalinity. It stems from the German words for degrees of carbonate hardness, I believe.
1 meq/L = 2.8 dKH = 50 ppm calcium carbonate equivalents

 

[kwgozy]

So once the ph, ca are at desired levels in the tank. Then that reading on the needle valve is where you would want to shoot for other than the mentioned occasional tweaking? You do the tweaking/adjustments based on ph, ca, alk of the tank correct?

 

[kwgozy]

Ok I know the DKH but was a little confussed on the kh.

Thanks

 

[Randy Holmes-Farley]

You do the tweaking/adjustments based on ph, ca, alk of the tank correct?

Mostly alkalinity. It responds much faster to over or under dosing than does calcium.

 

[kwgozy]

So is alk moves either direction, it is time to make a Co2 adjustment?

 

[Randy Holmes-Farley]

yes.