Home Up DIY 10/2


After looking at various other commercially available calcium reactors, I decided that whilst happy with the overall performance of many. there were nearly always certain features that I either didn't like, were lacking in the presence of other good features, or could simply be improved upon. Admittedly, manufacturers have certain limitations placed upon them in terms of production costs and time etc that negate the possibility of having an all singing and dancing design so being completely fair about it, I cant really condemn any of them. So after much deliberation over the possibilities of buying a unit and then modifying, I thought what the hell and decided to design and build my own.

So the first job I had to undertake, was to write down all the good features of the leading brands that I liked, all the features that I didn't, and then figure a way of combining the best of all, whilst avoiding or changing the worst of all.

Features to be included.

1. A large 230mm wide by 500mm capacity body totalling over 19ltrs. 'This means that having a larger surface area for dissolution, the Calcium carbonate doesn't need to be run as hard for a large demand, compared to smaller units'.

2. Diffusion plates and anti particle plates. To ensure an even flow of gas throughout the media, and to prevent premature ware of the pump impellors via particulate abrasion.

 3. Secondary de-gas and pH stabilisation effluent chamber. This makes the most of the low pH effluent, adding yet more Calcium and alkalinity to the effluent consequently raising its pH value before going back to the tank. The net result, is maximum efficiency of the gas used, maximum dissolution for the flow rate, and less effect on the systems overall pH value.

4. Recirculation of un-used gasMaximising efficiency, making the most of every ounce of injected Co2

5. Venturi fed gas and water injection. Ensures that incoming gas and water is mixed as quickly and efficiently as possible.

6. Solenoid valve assembly for automatic gas control via a pH controller and inbuilt pH probe.

7. Large sized bubble counter for fine adjustment when running manually.

8. Two independent and adjustable 1200lph recirculation pumps. Enabling super high flow when using static course coral branch media, or can be run singly for finer / lighter fluidised media.

9. Quick fill screw cap for topping up media. Without the need to remove sponges etc or drain down.

10. Complete lid removal  without the need to readjust settings whilst leaving all ancillaries attached.

The next task was to put all that into a 3d graphics program called Sketchup, and find a way of combining all those features into a logical, reliable and effective design. so this is what I came up with.


In the images above, you can see that the reactor comprises of the usual main body with a top flange that holds the main lid assembly on via a ring of bolts. In the lid, we also have a quick fill cap that runs right down through the diffusion baffle that hangs from the lid assembly meaning that the reactor can be topped up with no effort at all.. The lid also forms the main support for the Degas chamber, Gas solenoid, and bubble counter. This means that when the lid is removed via the ring of bolts, everything comes away with it still attached. This means you can empty and clean the main reactor body during maintenance routines without disturbing any of the settings or ancillaries.


The two 1200 lph recirculation pumps draw water and recirculated gas bubbles from the top of the reactor body just above the top diffuser plate, and pump back out through the base and two nozzles angled in such a way that they cause the water/gas mix to twist upwards through the bottom diffuser plate, then evenly through the media above.. Both pumps are controlled via flow taps when needed, or can be disconnected from the taps at times when the lid needs removing. (during building and ongoing development, these pumps were turned by 90 deg so that they were mounted vertically)


This top image shows the various gas feed lines. Coming in from the left we have the main input line that runs to the solenoid valve before going to the bubble counter. From here gas is taken and split to two venturi injectors which are set into the input side of the recirculation pumps. There is also a bleed line which sucks un used gas from the main fill cap tube and from inside the top of the Lid. Incoming tank water is fed into the recirculation pumps again via venturi injectors whilst outgoing water is taken from the top of the main reactor body, then to the degas chamber before finally going back to the main system (via the skimmer output pipe).

So, with it all planned out and materials ordered, it was then time to get the various components manufactured by a very good friend called Kevin who owns a CNC machine/Engineering company. Whilst the main body and false base are made from 3mm wall 230mm diameter extruded Acrylic tube, The base, inner base, diffuser plates, top flange and lid, are all made from 8mm thick clear cast acrylic.

The following drawings were used as the blue prints for the various components.


Top Flange.

This component is bonded to the top edge of the 500mm high main reaction tube. The groove in the top is for a 4mm thick 'O-ring, that will form the seal when the lid is bolted down on top of it (at this stage there are no holes drilled in the flange). The groove underneath is the seat for the reaction tube bond. The reason for bonding the two components in this way is that the strength of the bond is much much stronger than a standard flat face joint.

Inner Base

This component again has two grooves machined into it. The bottom of the main reaction tube is bonded into the upper groove. The false bottom (100mm tall 3mm wall x 230mm tube) is then bonded to this groove

Base plate

The base plate will form the bottom of the whole reactor assembly, plus the support plate for the two  recirculation pumps. The groove forms the bond seat for the false bottom tube.

Top plate / Lid

I actually made this component 'after' the main reactor body had been assembled due to the fact that I wanted to check the ideal locations / angles for the bubble counter (smaller protrusion) and degas chamber (larger one). For most instances though, Id say that the arrangement bellow would suffice with the two components at 90deg to one another. In this configuration (looking from above), the pumps would be on the left of the image. I haven't added any measurements to this drawing other than the dimension of the main circumference so that it matches that of the upper flange. I also haven't put any bolt hole dimensions or diameters as these would depend on your own personal preferences. ( my advice would be though, to remember that you need to have enough clearance so that the bolt holes don't get too near the O-ring gasket, and that there are enough of them to give an even pressure around the entire lid once tightened up).  In my case, I used 6mm plastic bolts with wing nuts.

Again, this was made from 8mm thick clear acrylic sheet.


Continue to page 2 for further construction images and info.


All images and design Simon Garratt.

These guys supplied the acrylic tube at a very reasonable price.

For all your DIY Acrylic needs.  Paul has the lot..



Home Up DIY 10/2