acripora and stylophora

Cleaning Your Calcium or Kalkwasser Reactor

Having a calcium and or Kalkwasser reactor as part of your reef aquarium system can be an invaluable tool to help keep your water parameters steady.  Like the rest of your reef equipment though, they must be cleaned routinely to keep them running smooth.   Both types of equipment have a decent amount of small hoses and moving pieces which over time can become clogged, resulting in the reef aquarium version of a heart attack.  This  could have catastrophic results for your tank in a whole host of ways.  Preventing ALL of these is obviously important so we are going to try and outline a few things that we do to maintain our reactors and hope that this is helpful for anyone else that is looking to get a routine down for maintaining their equipment.


Calcium Reactors and Reef Aquariums

At ReefNation, we use a Geo 818 attached to a 40lb CO2 cylinder as our calcium reactor.  This size cylinder lasts us about 2 years on the 600 gallons we run here at HQ.  We fill this reactor with media that is mostly made up of coral pieces we have pruned from our tanks.  In addition, we add some dolomite which adds magnesium as it is dissolved.  (For more information on how a calcium reator works, have a look here)  The basic premise is that the CO2 makes the water in the Geo's Reef 818reactor acidic which then dissolves the media into solution creating ions that help the reef tank maintain calcium and alkalinity.  Now for the dirty part.  We’ve found that after a few months, the walls of the reactor start to get a film on them and it makes it hard to see the media level inside.  Without being able to see how much media is in the reactor, you can’t tell when to add more.  If the level drops too low, the amount of calcium and alkalinity you are adding back into the system will be driven down.  It seems odd that an acidic environment like this with a pH right around 6.5 would have a problem with a film forming, but any naysayers can have a look at the picture.

Kalkwasser Reactors and Reef Aquariums

Reefkeeping is a constant ying and yang between many variables like temperature, salinity, calcium, alkalinity, and pH to name a few.  While a perfectly tuned, and I mean perfectly tuned calcium reactor should be able to add enough alkalinity to keep the pH of your system steady, that isn’t always the case.  We find that it is quite easy using our Neptune Apex controller to set the calcium reactor so that the alkalinity and calcium are maintained.  That being said, there is still sometimes a slow lowering of the pH in systems that are dosed with just a calcium reactor.  Enter the Kalkwasser reactor!

Funk that build up in calcium reactor over timeKalkwasser is a German work for “lime water”  and is calcium hydroxide ( CaOH) in a powdered form, but more on that in a sec.  The point of the Kalkwasser or kalk reactor in our system is to counter the pH lowering of the calcium reactor as they both slowly drip into our system.   While the pH of the calcium reactor output is about 6.5, the Kalkwasser comes out at a smokin 12.5.   To make this solution, the powdered Calcium Hydroxide (CaOH) is added to the kalk reactor where it is stirred by a Maxijet pump and is slowly forced out it as our top off pump kicks RODI water through it.  One note of modification on this process that we have made, is to program our Apex controller so that if a sudden drop of water level causes out top off pump to run for a while and raising the tank pH, the controller shuts off this pump for say an hour should the pH go up over a set number.  In our case that is a pH of 8.4.  This prevents the top off from running for a long time while dumping Kalkwasser with its 12.5 pH into your system.  Over time, this reactor also starts to get a buildup on the walls, inlet tube, and pump impeller and must be cleaned so that it doesn’t clog up or stop working.

How To Properly Clean and Maintain a Calcium Reactor

There are probably many ways to perform the cleaning on these 2 reactors, but with our busy schedules, we will try to outline what has worked best for us.  For the calcium reactor, we found that disconnecting the hoses and removing the media to a bucket were first important as they reduced the weight of the reactor from about 80 pounds to a manageable 20 or so.   Once the reactor was empty, we took it to the sink for a quick rinse and light scrub with an abrasive pad to remove any loose particles.  We then put the reactor down on the ground and filled it with a gallon of vinegar and then topped it off with RODI water before sealing the top back up.  This created an acidic environment inside even lower than that during its typical operation and we let it run for a solid 24 hours which makes the reactor look like the day we bought it.

A couple of additional steps we like to take are to poke a rod through all of the inlets and outlets of the reactor so that any solid deposits or closgs are loosened up.  This is a good thing to do both before and after running the water/viegar solution through it.  It is also a good idea to rinse the media that you have emptied into the bucket a few times with fresh water before returning it to the calcium reactor chamber.  This will get any detritus that entered the reactor out so that the water in the reactor can flow as freely as possible.  Finally, the media can be added back to the reactor, topped off if necessary and then all the air bubbles can be bled through the return line to the reef system as you return to normal operation.  On our system we perform this cleaning twice a year, but you may want to just do it by eye as you see things getting a little dingy inside your calcium reactor.

Cleaning the Kalk reactor

How To Properly Clean and Maintain a Kalkwasser Reactor

The Kalkwasser reactor can be cleaned in much the same fashion as we discussed for the calcium reactor with one main difference.  The scrubbing that needs to be done before the vinegar is added has to be done thoroughly since any Kalk paste or pieces that are left in the reactor pack a pretty potent pH punch even when you are adding a gallon of vinegar to the reactor.  You don’t want this leftover Kalk to diminish the cleaning power of the vinegar.  It is also super important with the Kalk reactor to make sure that you use a rod or something to push clean the input and output lines as these will certainly be starting to close off.  Other than that, following this regimen a couple times a year should keep your reactor working properly as it maintains the balanced water chemistry inside your reef tank.

Do you have any modifications of this cleaning process that you use on your tank?  Any suggestions you would like to share?


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