Kalkwasser and Nilsen reactors

[ReefLady]

I had a member request some information on kalkwasser and Nilsen (kalkwasser) reactors. Basically, how they work, what they do, why people use them, how to use them, etc.

I'll offer the information that I can - please feel free to jump in!

First of all, kalkwasser is a German word for lime water. Kalk (powder) is basically calcium hydroxide - you mix it with RO/DI to introduce it to the aquarium. Kalkwasser is considered a "balanced" additive, in that is maintains/adds both calcium and alk equally.

Other benefits of kalkwasser are that it precipitates phosphates, and it also raises the pH level of the tank.
Another benefit is that is can be a relatively inexpensive way to maintain ca/alk in a reef tank.

Many people drip kalkwasser manually. This is done by mixing approximately 1 tablespoon of kalk powder per one gallon of water. Stir/agitate well, and let this sit overnight. You would then pour off the clear water at the top of your container into some sort of dripping or dosing container.
Many people use IV line to drip their clear kalkwasser solution.
It is important to drip kalkwasser, rather than to add large amounts at one time - because of the high pH of kalkwasser (12.0 - 13.0), it can cause significant and harmful shifts in the pH if added to rapidly.

How much kalkwasser to dose?

Most people dose kalkwasser to replace all evaporated water.

When to dose?

Many people drip kalkwasser only at night, as this is typically when pH is lowest. If stable pH conditions in the tank allow for it, it can be dripped 24/7.

Nilsen [Kalkwasser] Reactors

Nilsen reactors are just a convenient way to dose kalkwasser. In most cases, it is pretty simple to rig up some sort of dosing container and tubing to manually drip kalk. Some people (like us!) opt for more convenience. The main reason we decided to use a Nilsen reactor was due to the amount of water we evaporate - up to 5g/day. Since we're away for many long weekends (and sometimes a week or more) on vacations, we searched for a more convenient way to dose Kalk. The Nilsen reactor is it.

The Nilsen reactor is basically an acrylic tube which contains RO/DI and kalk powder. Some models use magnetic "stirrers" - ours is simply connected to a Mag pump on a digital timer. The timer is set so that it turns on for 15 minutes every 4 hours.

Our RO/DI is plumbed directly to the Nilsen reactor, so we drip kalkwasser constantly, 24/7. We use a valve to adjust the drip rate.

Maintenance consists of adding a "bunch" of kalk powder (8-10 tbsps?) every two-three weeks. We've had the Nilsen reactor up for about 6-7 months now, and have had to replace the impeller in the mag pump once.

Here are a couple links for DIY Nilsen reactors:

JJ Geisler's DIY page - includes 3 Nilsen Reactor plans<

>Nilsen Reactor, Bill Esposito<

]>The Mantled Monster Nilsen Reactor page<

Hope this is helpful!

[Curtswearing]

Awesome info Reeflady. I think adding Kalk to my routine was one of the smartest decisions I've ever made. I was afraid to do it for the longest time for the reasons you mentioned above. However, it really isn't that hard.

I can't drip enough to maintain my calcium. I realize I have a choice of purposely forcing more evaporation so I can drip more. However, I just use a 2 part supplement for the rest.

[jks1]

Thanks Teri, been thinking about one of these for a while

[ReefLady]

Curt,

I've never personally tried this, but many reefers add vinegar to kalkwasser - for a few reasons. One being that it lowers the pH of the solution - by doing this, more calcium (hydroxide) is dissolved into the solution.

Take a look at these articles:

>Kalkwasser - In Depth<

>Kalkwasser<

> Expanding the Limits of Limewater: Adding Organic Carbon Sources<

HTH!!

[Curtswearing]

Thanks Reeflady,

Karma to you. I've read up on this subject but I've always been a little leery. I think I might give it a shot to see how well it works then I can report back.

BTW----Here's the warning on the back of a popular Kalkwasser mix that proves it does work as those links indicate.

Precautions: Contains Calcium Hydroxide, a caustic material. Remove to fresh air if inhaled. In case of eye or skin contact, flush with water for 15 minutes. If swallowed, drink 2 glasses of water followed by fruit juice or vinegar. SEEK MEDICAL ATTENTION! KEEP OUT OF REACH OF CHILDREN! Not for human consumption. For Aquarium/Ornamental fish use only. Not for fish used for human consumption.

[NaH2O]

RL, how do you determine the drip rate? Can the kalk reactors be hooked up to pH monitors and dosed as your tank needs it?

Thanks for the info!

[ReefLady]

RL, how do you determine the drip rate?

Since our evaporation rate increases/decreases seasonally, and often on a day-to-day basis, we just fiddle with the drip rate so that the sump doesn't get overfilled.

When we're away on vacation, we set the drip rate very low. Another outlet of our RO/DI is plumbed directly to a float switch in the sump, so if the Nilsen reactor is not providing enough drip to keep the sump level where it should be, that will kick in.

Can the kalk reactors be hooked up to pH monitors and dosed as your tank needs it?

I imagine it can be, unfortunately I don't know anything about doing so.

[fidojoe]

Cool, great info RL, I didn't know that kalk has another purpose other than supplementing Ca, and balancing Ph, I can't wait till I get mine

The other thing you could probably do is put a float switch on your dosing pump, so it will shut off if the water gets too high.

[middletonmark]

Sweet, thanks RL!

[mkpaulson]

I've been thinking about adding one of these to my system, the question I have is what prevents the kalkwasse power from being added to to your tank sense this mixes every couple of hours and is driping constantly?

[StoneyReef]

The kalk powder is denser than the resulting saturated solution when the kalk mixes with the water. The reactors are usually tall enough that they hold a gallon or so of clear saturated solution. If you used up that much solution then you would basically be pushing out the white powder that is in suspension from the mixing. As Reeflady mentioned, the kalk is dripped or added very slowly, thus you would not use up that large of a volume at one time. Additionally you add it sooo slowly that the powder has enough time to settle out of the saturated effluent. This is one of the considerations you need to take into consideration when setting up a proper dosing method with your tank specs. Small sumps that show a little evaporation rather easily can be set up with a float switch and a powerhead to feed it as a little bit of evaporation translates in a big height difference in the water column to activate the float switch. For LARGE sumps or larger sumps without a sectioned pump area, it is safer to use a drip method or a peristlatic dosing pump.

[ReefLady]

A few pics, as promised.

This first pic is a whole shot of the reactor. Ignore the large white flexible PVC in the foreground - this goes from the sump to the return pump.

[ReefLady]

This picture shows the John Guest ball valve that controls the amount of RO/DI that comes into the reactor, which in turn controls the drip rate (out).

[ReefLady]

This pic is the bottom portion of the Nilsen reactor. Keep in mind that the reactor is 3' tall.

You can see the kalk powder in the bottom, and the white piece of PVC directs the output flow of the Mag 2 pump (toward the bottom).

This portion of the reactor is basically where all the "mixing" takes place. All the water above this, though saturated with kalk, remains clear.

[ReefLady]

Again, here's a better shot of the whole thing - you can see where the mixing happens at the bottom, and the "clear" drippable kalkwasser is at the top of the reactor.

The red arrow at the very top of the picture is pointing to the output (drip) line. The drip, as you can see, comes from the very clear kalkwasser at the top of the reactor.