Calcium reactor effluent numbers?

tom obrecht

Active member
I'm curious what are normal numbers for calcium reactor effluent? I have a Korallin 3002 on a system with about 350 total gallons with all soft corals and clams. I have a tough time getting my calcium above 400 and keep my magnesium up. When I measured my effluent the other day I came up with calcium 740, magnesium 1320 and alkalinity 48. These were all done with a Hach test kit. Could these numbers be correct and if so could it still not be enough to keep my systems needs in check?
I keep mine at 6.4 that way my media doesn turn to mush, if you measure your calcium reading directly out of the effluent it will be streamely high is your free calcium reading that is the key, meaning testing it from the water colum of the aquarium.
Sorry, but I don't understand your answer. Are you saying the only thing I need to measure is the effluent PH? I do test the aquarium water but my calcium is usually 360-400. Only way I can get it above 400 is to add calcium chloride for I already does 4-6 gallons of calcium hydroxide daily.
If you are having trouble maintaining yoru calcium, alk at cosistent levels, then inncrease yoru bubble count and drip rate until you reach the desire levels in yoru tank.
Those were excellent numbers coming out of you calcium reactor. The key is the alkalinity out of the reactor. Anything between 20 and 40 is good. You can adjust the flow and bubble count up if your tanks readings are not coming up where you want them to be and just make sure the resultant alkalinity out of the reactor is in that range.
I was told a calc reactore effluent number to shoot for was three times what you would like your tank Alk to be. IE, if you want your tank alk to be
10 then your effluent alk should be right around 30.

I have a question about calc reactore setup also. Does increased effluent mean decreased alk? Or just more alk going into the tank? Reason i ask is I want to lower the effluent alk , because alk in the tank is getting too high for my liking.
That is why it is key to measure the alk in the effluent. If your alk is too high then it is time to adjust your effluent flow down a little bit. When you do that you will be decreasing the amount of alkalinity and thus calcium going into the tank. If after you decrease the flow slightly and then measure the effluent alk and it is higher or the same you can then decrease the number of bubbles per minute of Co2. Just remember to wait at least 24 hours or longer (I usually wait 2 days) to measure the effluent as it takes some time to stabilize at whatever new parameter you have adjusted.
The idea of 3x alk in the effluent sounds ok except that it will totally depend on the size of the system and the pace that the flow is coming out of the reactor...
It takes some patience but when you make one change at a time you will start to get a better feel for what is going on with your reactor.
Good luck...
ok, so i am pretty steady at ph of 6.6 on the effluent. So, Could i just keep the effluent the same(its REALLY slow already) and increase the pH steadily, thus dissolving less media and producing less calcium and alk????
I do not follow ph of my effluent. A lot of people do, but I do not totally understand why. As long as the alkalinity of the effluent is in the 20-40 range, you will be fine. If your flow is really slow enough then just decrease the number of Co2 bubbles/minute. The pH will most likely go up but really what is happening that makes sense is the alkalinity coming out of the reactor will just be lower. It is really just how you look at it I guess. ph just is not that useful for me since what I am really interested in is the alkalinity and calcium in my tank. To really use pH I think you would have to be calibrating your probes religiously and I think that many run into problems with adding too much Co2 into the sytem as a result. This of course are just my thoughts on this.
Anyway, good are on the right track nonetheless.
Knowing your pH of your tank is extremely important and it should be monitored. Knowing it for your calcium reactors effluent IMO is not really that important, but if you want to it certainly can not hurt anything.

However, just because you monitor it does not mean you will have less impact on your tank's pH, use less Co2, or prevent one's media from turning into mush. There are so many variables to consider that I think that implying that knowing the pH will keep you out of trouble is misleading.
Just the mention that different medias work at different pH levels indicates the complexity of the issue. How do you know for sure what pH to strive for for a particular media? Is it different per batch? How often should I be calibrating my pH probe? These are just a few of the many questions that should be considered when deciding if this type of monitoring is truly helpful.
IMO measuring your effluent dKH and your tank's dKH and pH on a regular basis is the way to go to stay out of trouble...
I don't even understand the effluent testing at all.
I just test the main tank and tweak from there. As you can see, just because you have "target" number in the effluent, it doesn't mean your tank is going to be where you want it.

Over time, you can tell by the response of your media whether or not you're too high on the CO2 end and too low on the drip rate, etc...I've seriously never felt the need to test effluent.
As long as you know the effluents dKH is at least 20-40 you know that your reactor is doing what it is supposed to be doing. I guess I just feel more comfortable knowing that information...
After that, as long as your bubble rate and flow are the same you should not have to worry about your effluent numbers and can just measure the tank parameters and adjust up or down as necessary from there.
Knowing your pH of your tank is extremely important and it should be monitored

my reactor is set up and running



All levels holding steady for at least two weeks. The problem: my tank pH wont get above 7.9. Ive tried all the usual methods Randy suggests over in the chemistry luck. Could this be due to something maladjusted on the reactor?
I do not know if everything pH wise was fine before you started your reactor but you may want to cut back a bit and see if the pH goes back up.
Just make sure that your pH is what you think it is. Recalibrate the probe or make sure it reading correctly with control fluids. If everything else is doing well you may be ok...I personally do not like to go below 8.0 even though some say that they can get away with 7.8....
In reference to your effluent alk, it seems a bit low (I like 20-40). This could be a media problem. You may be using too much Co2 and not dissolving enough media even though all your parameters are where you want them to be. The result could be a lower pH just as a result of that. In other words if the media is dissolving easier with less bubbles of Co2 then maybe your pH would not be going so low...Just a thought...
I use carib sea geo marine florida crushed coral and that has worked really well for me.
Good luck
Im using twelve bubbles a minute and ph of 7.0. im cutting back the effluent flow and lowering the pH in the reactor. Ill see if that helps.
Thanks Randy,
Those were helpful to me even though I did not realize I could use to read them. Where does one get Dolomite? I would prefer to add Magnesium this way...
Those resources should definitely be helpful to you. You are on the right track regardless...
Good luck.