Another question about CA reactor adjustment

[Anonymous]

I have been having an issue getting my reactor dialed in properly. About 2 weeks or so ago I had 450CA and 16dKH. So I reduced the CO2 going to the reactor and it dropped my CA to 350 and 16 dKH. So I dropped the CO2 again and today the CA is 380 and 16.8dKH. I started adding kalkwasser to my RO/DI to get my CA up and the theory was that raise the CA to the level I want with Kalk and the reactor would maintain. However after dosing it for 6 gallons of top off over a week or so, my CA dropped and dKH raised. The exact opposite of what I wanted to happen. So now my BPM is about 15 and not sure if I can dial it down a whole lot more. Any more suggestions to get my dKH down some?

 

[fyrefysh]

How often do you do water changes and how large are they? Sounds like your buffer may be out of whack? Have you tested the magnesium level in your water?

 

[Anonymous]

I do water changes about every 2 weeks of 5-10%. I don't check magnesium.

 

[jdeets]

I remember your other thread. I don't understand how your alk could go higher and Ca drop when you turned down the reactor--that makes no sense chemically or otherwise. Check the alk again. Make sure your test kit is good.

To get your alk down, quit adding the alkalinity component, and maintain calcium with a one-part additive. Using kalk won't change the ratio of Ca to alk, because kalk is balanced supplementation. Therefore--turn off your CO2 completely, and test alkalinity until it drops to where you want it--I think you were lookng for 12 dkh if I recall. This should happen within a few days.

As your alk drops, keep your Ca where you want it by using calcium chloride.

Once these numbers are where you want them, fire up the reactor, and it should maintain everything in balance.

 

[Anonymous]

Yeah I know it makes no sense. Thus the reason for more questions lol. I tested it 3 times and got the same each time. I am using salifert test kits that are about 3 months old. Very confusing.

 

[jdeets]

Well, start by turning off the CO2, and test every day or two, and see what happens. If your alk stays constant while your Ca drops, then you have a bad test kit. It would be impossible for your Ca to drop with constant alk if you're not adding anything to the tank.

Your Ca should drop 20 ppm for every 1 meq drop in alkalinity. I think you usually work in terms of dKh, but the kit yields both units.

I'd highly recommend this article by Craig Bingman, which is a great basic lesson on the Ca/alk ratio. Get a handle on these concepts and it will take a lot of the mystery out of basic Ca/alk chemistry and help you more effectively use the Ca rxr.

 

[Anonymous]

Thank you, I really appreciate the help.

 

[Anonymous]

So here we are a month and 4 water changes later. I stopped using Kalk and started dosing Calcium chloride. The CA has pretty much leveled out at 390. The CA reactor has been off for a month as well. dKH is still at 11.8. I am not certain what the issue is, but I have got new salt, rodi water and changed my tanks worth of water in a month and still high alk. The test kit could be the culprit I suppose, although they are fairly new and salifert. So would the concensus be that the test kit is bad? Is 11.8 too high still? I read that NSW is 8. Any thoughts on how high I should have it?

 

[jdeets]

Actually, 11.8 is not really all that high. That's 4 meq, which is fine for our captive systems.

What kind of calcium/alk demand does your tank have? I find it suspect that your alk hasn't dropped without doing anything but water changes. However, if your tank doesn't have a high demand for ca/alk, then maybe water changes are sufficient.

I would definitely try another test kit--or take a water sample to the LFS if there is one nearby, and have them check it for you.

 

[Anonymous]

I have sps and a clam so I would think that the CA demand would be up there as well. I think I am going to try a new kit to be sure. I doubt my LFS's would have a kit available to use. Thanks again.