Calcium reactor/kalk

[Samper]

I'm just now learning a bit about these and I think for my new setup it would be wise to have one.

First is a Ca and kalk reactor the same thing?
How do they work?
How are they set up?
What are some good brands to look into?
How big of a bottle do I need and how long is it expected to last?

[Samper]

This is what I've learned so far.
When I get one I need to get a dual chamber. This helps control ph swings in the system right?
Also the co2 used is determined by the tanks needs of Ca and I will need a ph probe or meter and a bubble counter.

[Ninong]

I'm just now learning a bit about these and I think for my new setup it would be wise to have one.

First is a Ca and kalk reactor the same thing?

No, they are two entirely different things.

How do they work?

A Kalkreactor (aka Nilsen reactor) is an acrylic cylinder that holds a mixture of freshwater (R.O./D.I.) and calcium hydroxide (Kalkwasser, Mrs. Wages Pickling Lime, etc.). Think of it as a mixing container for mixing up limewater automatically. R.O./D.I. water from an R.O./D.I. top-off reservoir is metered into the Nilsen reactor's container as needed to replace limewater that is dispensed from the container. At the bottom of the cylinder there is mixing paddle -- magnetic shaft of a small pump with a paddle on the end that is activated by a controller (timer) to turn on at preset intervals to mix the contents of the cylinder. You would set the thing to come on for a few minutes every few hours to mix the limewater because there is always a lot of calcium hydroxide at the bottom of the cylinder that is available to mix with the incoming R.O./D.I. water. Think of it this way: Supposing you were to mix up a batch of Kalkwasser (limewater) but instead of using just 2 tsps per gallon of freshwater, you used 1/4 cup per gallon. You stirred up the bucket but the maximum that will go into solution is 2 tsps per gallon, so the rest settles back down to the bottom. You siphon off a few cups of clear limewater from the top of the bucket which causes fresh R.O./D.I. water to enter the bucket from your reservoir because you have it set up to do that automatically. Now you would need to stir up the contents of the bucket again so that some of the stuff at the bottom would go into solution. You would want to maintain a saturated solution of calcium hydroxide. Now think of somebody (Nilsen) designing a device to do that automatically. That's a Kalkwasser reactor. It is nothing more than a way to automatically add limewater to your tank to replace evaporation -- either by float valve control or preset metering. I don't have one, so if somebody who has one sees anything wrong with that explanation I'm sure they'll correct me.

A calcium reactor is a cylinder that holds calcareous media -- either aragonite or limestone. I say cylinder because most calcium reactors are made using acrylic tubes but I should probably say chamber because some of them are square. R.O./D.I. water is fed to the calcium reactor's chamber where it mixes with the calcareous media. This media will dissolve more readily at lower pH levels. In order to get the pH levels down, you add CO2 (carbon dioxide) via a fine needle valve on your CO2 tank. The bubble counter measures the amount of CO2 that you are feeding to the reactor. You adjust the valve to get the desired flow. You want to get enough CO2 but no more than enough because you don't want excess CO2 going into your aquarium and lowering its pH. Most people use a 5-lbs CO2 tank, which is about the smallest that reef tank owners would consider. If you have enough space for a larger one, get a 10-lbs tank. If you have a really large tank and can accomodate a 20-lbs tank, that's something to consider but it would be very heavy. How often you have to have the CO2 tank refilled depends on the calcium demand of your aquarium. Typically a 5-lbs tank would need to be refilled every 3 to 6 months. Either that or you should have gotten a larger CO2 tank.

The idea behind the calcium reactor is that the aragonite media contains the correct mix of trace elements necessary for coral skeletal formation because it once was coral skeletons. So if you could get this aragonite to dissolve, you would have an ideal calcium and carbonate additive to maintain proper levels of calcium and alkalinity in your aquarium. Lowering the pH will allow the aragonite to dissolve faster that it would otherwise. So you add CO2 to lower the pH in the reactor's chamber so that the media will dissolve rapidly. Your aragonite sand bed in your aquarium dissolves over time but it dissolves very slowly compared to how fast it would dissolve if the pH were lowered. Of course, if you accidentally dropped the pH in your aquarium down below 7.5, your sand bed would dissolve a lot faster. Even if your aquarium's water tests at 8.2 pH, there are lower pH levels in the micro-areas surrounding individual grains of sand in the sand bed. This is the result of the metabolic action of the denitrifying bacteria. So this results in your sand bed dissolving very slowly. This has the benefit of adding calcium and carbonate to your system but it is a slow process. Obviously you would get better results in this area with a 6" DSB than you would with a 1" sand bed. And you would get no benefits with a bare bottom tank. So if you have a bare bottom tank you wouldn't have any assistance from your aragonite sand bed in maintaining the calcium and alkalinity levels in your tank; you would have to accomplish this with a calcium reactor or two-part additives.

The effluent that is discharged from the calcium reactor contains all the elements that were in the media but it also contains a little CO2 which would immediately form carbonic acid (H2CO3) when it enters your tank. This results in lowering the pH in your tank. So some people might choose a calcium reactor with two chambers in sequence so that the CO2 gets all used up before the effluent exits the second chamber. This is not really necessary if you have a properly designed calcium reactor but let's just call it a safety factor. Or maybe you started out with a single chamber calcium reactor when your tank was fairly new and it worked fine but now that your tank is stuffed with SPS corals, you find that your calcium reactor is too small to keep up with your tank's calcium demand, so you add a second chamber to increase its capacity.

How are they set up?

They come with directions. I think you can get a general idea from the above.

What are some good brands to look into?

There are many brands. This is like buying a car -- a lot depends on how much you are willing to spend. You could buy a $3,000 Schuran calcium reactor or a $250 model from a hobbyist turned craftsman. I don't have one so I won't offer you any advice on exactly which model to choose because it all depends on your needs and your budget.

How big of a bottle do I need and how long is it expected to last?

The two most popular sizes of CO2 tanks are 5 lbs and 10 lbs. Ideally you would want to be able to go about six months between refills because who wants to have to run down to the local welding shop for refills every other month. You can get them refilled at welding shops, beverage outfits and hospitals. Welding shops are the most likely to be willing to accomodate you. For example, I found a place locally (via the Yellow Pages) that said they would refill a 5-lbs CO2 tank for only $5.00. I think most people pay about $10 for that. I was just curious and wanted to see if there was a local source for refilling the CO2 tank if I decide to buy a calcium reactor later on.

[Samper]

Wow once again Ninong to the rescue. I'm just curious why you don't use one?
From the readings I've found from people that use them it's considered a must have piece of equipment right up there with their skimmers.....usually euro reef.
When setting up one of these do you have to test your Ca and Alk on a daily basis for a while?

I definately don't need the kalk reactor it's easy enough to just mix up what I need although it would be nice to not have to mix it daily.

[Ninong]

Wow once again Ninong to the rescue. I'm just curious why you don't use one?

Mainly because there is no room in the stand's cabinet to fit one. I would probably have to locate the calcium reactor and the CO2 tank outside the stand if I ever get one.

From the readings I've found from people that use them it's considered a must have piece of equipment right up there with their skimmers...

No, it's not as important as a skimmer because you can accomplish the same thing through other means. It's more of a convenience thing more than anything else because it frees you from having to mix and dose Kalkwasser every day.

It becomes more and more of a necessity as the size of your aquarium and/or its calcium demand increases. You may reach a point where even if you use nothing but limewater for all of your evaporation replacement you still can't keep up with calcium demand.

When setting up one of these do you have to test your Ca and Alk on a daily basis for a while?

You would have to test your calcium and alkalinty as often as necessary to assure yourself that they are in the proper range no matter what equipment you are running. Obviously if you are making ch-ch-ch-changes to your system's equipment you might find it necessary to test more frequently until you are confident that things are going according to plan.

I definately don't need the kalk reactor it's easy enough to just mix up what I need although it would be nice to not have to mix it daily.

Most people get a calcium reactor so that they can forget about Kalkwasser completely. Some people with really large tanks with high calcium demand will find it advantageous to add limewater in addition to having a calcium reactor. Adding a Nilsen reactor accomplishes this task automatically. People with super large tanks may find it desirable to run a calcium reactor and a Nilsen reactor and dose a two-part additive like B-Ionic occasionally. Everything depends on the size of your tank's calcium demand and exactly how high you want to keep your calcium and alkalinity levels. If you are running a very large tank (500+ gallons) that is predominantly SPS corals, you may end up with one or two calcium reactors, plus a Nilsen reactor and then even with all of that you may still want to tweak things with a little extra Part A or Part B every now and then to keep things exactly where you want them, especially if you want your calcium at 450 ppm and your alkalinity at 12 dKH.

[Ninong]

Here is an example of an extreme setup: http://www.underseadiscovery.com/gadget2.htm

That empty tank is a 718-gal Starphire glass tank (96"L x 48"W x 36"H x 3/4" thick Starphire glass). That picture was taken three years ago. The tank is now full of corals and fish.

Water parameters are maintained as follows: 450 ppm Ca, 10-12 dKH alkalinity, 1300 ppm Mg. To accomplish that the aquarist employs two 42" tall Korallin calcium reactors (in sequence) plus a Kalkwasser reservoir with a metering pump to replace evaporation. And, in addition, he occasionally adds calcium chloride and sodium carbonate (two-part additive) to adjust values as necessary. He also has a super-expensive Sander-Helgoland AQ300 skimmer.

P.S. -- Don't get confused by the use of the term "Kalkreaktor." That's German for "chalk reactor" and it is what we call a calcium reactor or, more properly, a CaCO3-CO2 reactor. A Kalkwasser "reactor" is something else and not the same thing as a "Kalkreaktor." A Kalkwasser reactor is also known as a Nilsen reactor or a Kalkwasser stirrer. I think "stirrer" is a much more accurate description anyway.

P.P.S. -- If you are interested in seeing how someone with 20 years experience has set up his state-of-the-art 718-gal reef tank and his 300-gal FOWLR tank, order Wayne's book through his website and he will include a 70-minute video of mass spawning of Tridacna spp. clams in his reef tank at no extra charge. I have the book and the video and I recommend them to anyone planning a large setup or just dreaming about one.

[Samper]

Thank you Ninong.

I ordered the book a little while ago and in the paypal comments box I mentioned to Wayne that you sent me. Don't know if you know him personally or not but at any rate I'm sure he'll appreciate it. Thanks again for all your help and the lengthy responses.

[dougc]

There is another reason to run both a calcium reactor and a kalk reactor. As has been stated, a calcium reactor tends to lower pH. Kalk, on the other hand, can raise pH. Running both provides a better balance than either alone, similar to that acheived with a 2-part solution like B-Ionic.

[Ninong]

There is another reason to run both a calcium reactor and a kalk reactor. As has been stated, a calcium reactor tends to lower pH. Kalk, on the other hand, can raise pH. Running both provides a better balance than either alone, similar to that acheived with a 2-part solution like B-Ionic.

And one more reason that I forgot to mention is the fact that Kalkwasser (limewater) precipitates phosphate.

[Samper]

This 75 is getting very expensive....oh well!