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Calcium Reactor Question - Tdwyatt(?)

3036 Views 8 Replies 5 Participants Last post by  tdwyatt
I am running a two-column, MyReef Calcium reactor (have been for about three weeks). I have the following corals in my 190 gallon tank - a number of mushrooms, some tiny yellow polyps and zoos (last time I buy coral online :( ), a hammer, a leather, a closed brain, a flowerpot, and one pulsing Xenia. Everything other than the polyps and zoos are doing great (and I think with those two its a miracle that they are alive at all).

The problem I have is with my water parameters. My kH is WAY(!!!!) too high - around 14.6 dkH; my Calcium is around 470 ppm, and my pH (at its peak) around 8.55. I have already toned down the effluent flow to where you can see separate distinct drops form (but the flow is continuous).

1. Should I slow down the effluent flow even further?

2. What is the effect of increasing or decreasing the flow of CO2 into the Calcium Reactor?

I would love to bring down the kH a fair amount and the pH a little bit without bringing down the Calcium. Is that possible?

Thanks in advance.

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1. Should I slow down the effluent flow even further?
I'd cut the CO2off for a few days and test again.

2. What is the effect of increasing or decreasing the flow of CO2 into the Calcium Reactor?
The more co2 going in means more media dissolves(to a point) more Ca/Alk and a lower reactor effluent pH.

The less co2 going in means less media dissolves, giving off less Ca/Alk and a higher pH.

Your ph is pretty high. I'd add nothing only make up water to your tank and let everything come back down, after a week of the reactor being Co2-less.

If you have macroalgea growing you could cut the lights for a day or 2, and that might help bring the pH down a little.

Hopefully Tom will chime in soon.
Forgive my ignorance, but it doesn't appear to me that you have enough of a calcium drain on your tank to necessitate a calcium reactor.
I thought reactors were mainly to automatically replenish calcium in tanks with stuff like SPS and clams that need a ton of calcium to grow without having to use a kalkwasser doser or to manually add calcium daily.
I have a 55g tank with inhabitants like yours, and only have to dose a little calcium every couple weeks to keep up with what the coralline and LPS are using (which isn't much).
I'd say (in most unscientific terms) that the calcium reactor is overkill at this point without a lot of organisms actively removing calcium from the water...
but then again I'm still wet behind the ears myself. :D

Sorry I really can't help with the problem... but since I'm going to start growing some SPS and Maxima's in my tank I'll probably be looking into a reactor sometime in the near future... your questions will no doubt benefit me as well when I get to that point. :)
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Valid point about the overkill :) The problem was that earlier my Calcium was hovering around 350-360 ppm and because I do plan on having SPS someday (soon I hope :funny: ) I figured I might as well get one now and learn how to tune it in right.


Thanks for the suggestions and clarifications on the interactions between pH, alkalinity, and Calcium.

Thanks again.

My tank is a 120 with a moderately heavy SPS population. Here's what's worked for me: I set the effluent drip rate to a fast, almost continuous drip. From there I only adjust the CO2 bubble rate. I never touch the effluent drip rate. I started with 45 BPM and tested/adjusted weekly. I haven't had any PH problems so I can't comment on that.

I'm sure Tom will have a more detailed post.:)

JM.02, IMO
ldmk said:
The problem I have is ... My kH is ... around 14.6 dkH; my Calcium is around 470 ppm, and my pH (at its peak) around 8.55. I have already toned down the effluent flow to where you can see separate distinct drops form ...

1. Should I slow down the effluent flow even further?

2. What is the effect of increasing or decreasing the flow of CO2 into the Calcium Reactor?
Hey KM, the two posts already presented have brought up a few of the points I would consider, usage of the alkalinity (low utilization) and your CO2 bubble rate. The effluent rate sounds about right to me for a 190, although with your populations in the tank, it may still be too high. Before you do anything, post your methodology for testing your pH, your alkalinity, and your Calcium. Also, if you use a pH meter, clean the probe and make sure it is calibrated, as much will depend on accurate measurements of the effluent as well as the water column.

Personally, unless the tank presents problems with your inhabitants, I wouldn't do anything to change it initially. The high alkalinity will come down as your coralline algal pops increase, as well as will your Ca as utilization of the calcium goes up. The excesses of both will salt out in the tank if conditions are right (and if they go bad, you will see a tank "snow out" as the Ca and carbonate/bicarbonate combine under the right/wrong conditions to form CaCO3.

Assuming your testing methodology is good and that the meter is clean and calibrated, there are several events that may be occurring that are driving your parameters up (they really are not too bad). Part of the high alk level is that your alkalinity is a product in your 2 column system of excessive dissolution of the aragonite medium by high levels of CO2 (as carbonic acid). The bubble rate that you have would prolly be a little high for a single column system, but here the second column acts to neutralize the excess CO2 such that your Ca prolly is at supersaturation and is precipitating out in the 2nd column as the pH rises from what is prolly around 6.5 to 6.7 to a near neutral at the effluent (this is an estimation on my part based on what your water column presents under the current conditions). The carbonate/bicarbonate portion of the effluent is much more soluble than the Calcium ion portion, and is further affected by existing CO2 in the water column. It will stay in solutiion at its relativly near-saturatioin state even as the pH rises as the column dissolves the aragonite in the second column. This is why your alk is so high and your calcium would still be near 500 ppm.

I would be interested to know what your pH of the effluent is at the point where it enters the tank/sump. Take a small mason jar and capture the effluent where it drips into the tank, place a pH probe in it, and let it run for a few hours (and overflow into the water column) and check the pH. If your pH is more than 6.7 or so, then what we have discussed is the most likely scenario. As you slow down the rate of delivery of CO2, you should see a corresponding drop in alkalinity without much of a drop in your Ca delivery rate. Keep good records of your pH, alk and Ca tank levels as the CO2 rate of delivery is slowed, and allow for 2 to 3 days to pass between each final evaluation, testing at the same time every morning and evening during your adjustment period (I would test your calcium and alkalinity 3 times at each teseting and take an average of your values). When you see a corresponding drop in both your alkalinity and your Ca in the water column of the tank, then you have found the "sweet spot" for the CO2 delivery.

If the critters look good, there is no rush to do this, but it will save you from wasting your CO2. If you had a shorter column (or just 1 column), you would see a drop in your overall pH at higher delivery rates. If you were delivering insufficient CO2, you will see a high er overall pH but your Calcium may be low, but even that will depend on many many variables. With the long column (2 columns), I would think that this is the most likely scenario. You might want to read Randy F-Holmes article in Advance Aquarist for a more detailed discussiion of some of the variables on this

Read the article, and go ahead and adjust your CO2 delivery rate but leave your effluent rate as Rick had suggested. Record the results, and continue twice a day testing for at least 3 days in a row without changing your delivery rate. Make sure to do your bubble rate changes slowly in order to determine the actual effect on your tank. Regardless of what you decide to do, definitely make the changes slowly, and check your equipment and your methodology before deciding to make any major changes.

HTH, many variables, this should give you a starting point.
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Thanks to everyone for your comments and suggestions.

Testing Methodology I am using a Pinpoint pH monitor - I haven't calibrated in about a month (out of calibration liquid - I have to get some). The probe is clean - I just cleaned it a couple of days ago - and I get the same reading using two different monitors (I "borrowed" my wife's monitor off her FW tank :funny: ). I am testing the Calcium and Alkalinity using a Hagen titration method - not a super accurate test I know but I'm hoping its not too far off. It may be time to spring for the Salifert or Hach tests (I don't even know where to get the Hach tests - it's just that CyberChef is such a fan of Hach :)).

I've already turned the CO2 bubble rate down. I will definitely get a pH reading on the effluent and post it soon. I'll read the article in a few days (right now I am trying to digest the suggestions I've received so far). As Tom pointed out my critters and the coral seem to be thriving and so I'm not going to rush - I'll see how the lowering of the CO2 works first.

Thanks again for all the suggestions, and Tom special thanks to you for taking the time to clarify this rather confusing topic.

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:D :D :D :D :D :D
I have thought about this a lot since reading the threac, and I am still a little surprised by the pH at 8.5 with a Ca/CO2 reactor. This is almost always a result of insufficient CO2, usually in the presence of limewater additiions rather than CO2 reactors.

I would still clean and recalibrate the pH probe, just to make sure... The situatiion could occur as we have described, but I am still a little incredulous..

Jeeze, it is 3am here... :eek:

got to go to bed...
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