by Dr_DBW

A calcium carbonate reactor is something that is very easy to build. There is nothing to their design and you can pick and choose a design that suits your DIY abilities. This is my first DIY calcium carbonate reactor and was designed so that it was pretty much just fitting the pieces together and gluing them. No real work involved in having to cut, shape etc the pieces.

This is no longer the reactor that is being used on OZ REEF, it has subsequently been replaced by a more advanced and neat design out of acrylic. Some quite details on that unit will be added at a later date (however it wont be too details since that design is the basis for some commercial units that I now sell). This is still being used somewhere though, I sold it to a fellow member of MASOV (Marine Aquarium Society of Victoria).

The basic design of most calcium carbonate reactors is to have a recirculating column filled with calcium carbonate with a slow water flowrate through the entire unit. The recirculation has some ineffiencies in terms of the amount of carbon dioxide that is required to dissolve the calcium carbonate, but it makes it very easy to make, tune and run. Passing the injected carbon dioxide through the recirculating pump also assists in the dissolution into the water. Below is the diagram of this design that was used.

Diagram of the calcium carbonate reactor.

For this particular construction a large number of simple PVC fittings were used, so that it was just a case of gluing the majority of them together. The only more advanced part was having to drill two holes through the side of the column and one in the lid. The former were for the recirculation loop and the latter for the water outlet. This was achieved by using a hole saw and making the size just under that of the PVC fittings to go through it. Then apply a liberal amount of PVC cememt and slip it through. Worked very well and there was no leakage problems.

The external recirculating pump doesn't have to have a very high flowrate at all and I used an Eheim 1048. Has never missed and beat and is still running 24/7 on the new reactor. It has been going no stop since 1997.

Below is an image of the finished reactor. The vinyl tubing running around makes it a bit untidy and I don't think I would do it like that again, but that was the limit of my ability at that time.

Image of the finished reactor.

Here is the various fittings around the recirculating pump. It all looks a bit messy and all, but it does the job :) On the inlet side of the pump is the water inlet, carbon dioxide inlet and water from the base of the column. Outlet side has the water return back to the aquarium system and the water outlet to the top of the column. Was was drawn from the base of the column as this avoids the pump running dry if there is too much carbon dioxide going into the unit and it fills up.

Close up of the fittings around the recirculating pump.

And finally this is the bubble counter, which is required to be able to monitor the flowrate of carbon dioxide into the reactor. This was made out of an epoxy putty container, with a check valve glued onto either end. Water is sucked in through the bottom to fill it up, then the bottom length of airline is connected to the carbon dioxide source.

Bubble counter.

Carbon Dioxide Supply: Yeast Method

It was the original idea was to use the below as the carbon dioxide supply, and it was used to start with after it was built. But it was found that it was just a little bit too fiddle to keep a good constant pressure. But the good thing is that it can be done, and if you have a bit more time and patience, or lack of money, then I am sure that it can be used for sustained periods of time with no hassle what so ever.

Diagram for the yeast method of supplying carbon dioxide to a calcium carbonate reactor.