The following images show the build process in various stages of construction. 

One thing to be aware of when bonding acrylics, is to know the difference in glue requirements between 'cast' and 'extruded'. Cast is the easiest to bond because at a molecular level it isnt under any 'tension' in its cool state. Extruded on the other hand is, because during manufacturing it  is heated and stretched into shape then cooled rapidly leaving the molecular bonds tight and under tension. If you use the wrong glue on extruded, The edges will crack and craze giving a very weak joint at best, and a completely ruined component at worst. In this case (using cast plates and Extruded Tube) I decided to use a solvent called 'extrufix' which is specifically designed to work with either. It is a water thin solvent that works by capillary action after being injected via a syringe along the joint. the solvent literally tracks and fills the bond all by itself. It should be remembered though that these water thin solvents are not 'gap filling' so any joints they are used on, need to be well matched and a snug fit prior to bonding.

I n the image above left, you can see the main components, with the base plate bottom, then a short section of tube supporting the Inner base. The main reactor tube and top flange, with the now drilled and bolted top plate in position over the silicone O-ring that is sitting in its groove (the white ring).  You will also notice some short sections of solid acrylic rod stuck inside the bottom of the main reaction chamber. These are supports for the bottom diffuser plate that will be added later and are just long enough that they allow space under the plate for the two bulkhead fittings and elbows that make up the inlet pipe work.

In the image above right, You can see the diffuser plates added in. The bottom plate simply sits on the supports that were previously bonded to the inside of the reaction chamber, whilst the upper plate is bonded to the lid by way of 4 x support legs (again made from 10mm acrylic rod) Both diffuser plates are made from 8mm thick acrylic discs made just smaller than the internal diameter of the main reactor body. This ensures a good snug fit so that no media can make its way down past the lower plate, or up past the upper plate. If this were the case, fines would make their way into the pump assemblies causing damage over the long term which is a regular fault with many calcium reactors. Both plates were perforated with 5mm holes spaced at 10mm intervals.

In these two images you can see the quick fill lid which consists of a 50mm VDL bulkhead fitting and screw on end cap. Note that  the diffuser plate support legs, are long enough to leave a good gap between it and the lid face, but not too long (approximately 1.5" which will leave room for the Probe holder and pH probe to sit once fitted). its important that the bulkhead extend down past the bottom of the diffuser plate by a good 1/2" so that when the top sponge is put in place, the filler extends 'through it', to allow open access to the media column. This allows you to top up the media without any more effort than simply unscrewing the cap, after turning off the recirculation pumps and main water feed to the reactor. These shots were just dummy shots with the diffuser plate tacked in place. I would advise 'not' bonding it to the lid, until such time as the water feed, pump outlet, and pH probe bulkheads have been fitted to the lid.

In these shots also, you will notice the bubble counter tube. This tube simply consists of a 200 long, by 50mm diameter tube that has had a flange bonded at the top and blanking plate bonded at the bottom.  Much the same as the main reactor body, the bubble counter top flange also has a 3mm wide by 2mm deep groove machined into it to house an O-ring seal that seals against the main lid once bolted up. In these shots you will also note that the holes have also been drilled and bolts put in place that will seal the assembly to the main lid which has the previously mentioned extension to cater for it. Not shown in these images, are the inlet and outlet fittings for gas feed, that have yet to be drilled and fitted. You may be wondering 'why' I went to the trouble of fitting an O-ring flange to the bubble counter. Simply put, it enables me to take off the bubble counter for cleaning etc without having to remove the entire lid assembly. If I had bonded the top of the tube directly to the main reactor lid, instead of an O-Ring flange, then I would also of had trouble filling and draining it as well as cleaning it out.

All images and design © Simon Garratt.

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