After putting together the main bulk of the  tank. It was then time to fillet all the joints and insert the brace bars. After a bit of a chat with Keith at Windsor aquatics about filleting and how thick they needed to be for the dimensions of the tank and glass thickness. I opted for 1" wide fillets along all the major joints. Basically, it was a simple case of letting all the joints 'go off' and then cutting out the surplus silicone that's squeezed out of the joints on assembly. Once this was done, all the joints were wiped down with thinners to remove grease and fingerprints (1). Masking tape was used to line each run, leaving 1/2" clear on each edge (2). Then a very thick bead of silicone was pumped along the joints and the end of a surplus silicone tube was used to smooth along each joint forming a nice smooth fillet, with the surplus being pushed outwards onto the surrounding masking tape (3/4). This was then removed strait away leaving a nice joint. (5/6)

11.                                                                                2.

3.                                                                                4.

5.                                                                      6.

These joints were then left to go off for a week ( This is something worth remembering about building big tanks. You need to allow more time for silicone to go off properly because the beads are so much thicker than smaller tanks. Although it skins over quite quickly, the underlying silicone will take considerably longer to fully 'cure' right back to the bond faces, so its important to be patient ).  After letting it all go off, It was time to fit the brace bars. Initially I had to cut a small 24mm section of silicone out from each upper corner of the main beads  'up the sides of the tank' so the brace bars could be pushed into place for a nice snug fit at the corners. Fitting was quite simple. Using some pre-cut lengths of timber, a thick bead of silicone was run along the one edge of the front and rear brace bars, which were then pushed into place against the front and back panes squeezing the surplus silicone out as they were pushed home, with the corners sitting in the small gaps id cut into the side bead.. The lengths of timber act as support for the brace bar to rest on whilst the silicone cures. Afterwards, It was simple case of cutting away the surplus, leaving a nice clean joint so no silicone is visible (7). The final job was then to add the side brace bars which rest on top of the front and rear ones, with a large blob of silicone between to add bond strength as well as the silicone bond to the side panes (8), and the centre brace as the last one. likewise, these were also trimmed of surplus silicone afterwards. (note that in these shots, just like the rest of the tank. The brace bars have ground and chamfered edges. This is essential for safe working on the tank. The last thing you need is a tank that slices your arm every time you try to work on it, or rub yourself along a brace bar.)

7                                                                                                     8

The final part of the tank assembly was the addition of the full length weir plate which is angled at 45deg away from the back glass. Just like the brace bars, three wooden supports were used to rest the weir plate on whilst it was bonded at the correct angle to the back glass and sides. Once set, the wooden supports were removed and the bottom edge was masked off with a fillet bead run along its length to form a permanent seal.  In images 9 and 10, you can see the weir attached in its final position across the back glass with the overflow holes set just below the level of the weir's top lip. and the rear brace bar above, that will act as the fixing point for the weir combs once fitted

9                                                                                                              10

Once everything was cured and trimmed off. It was time to seal the 50mm outlet, and 40mm return bulkhead fittings into the base of the tank, and seal down the outlet strainers over the top with a few blobs of silicone. When fitting the bulkheads, I fitted them upside down (thread, inside the tank) this was done for a reason. When dismantling the tank at a later date, It means I wont have to cut the pipe work sections to remove them, I can just unscrew the fitting from inside and drop the whole assembly out through the base as one section. When fitting the bulkheads, both the rubber and plastic washers are discarded (the rubber rots after a while causing leaks) and the fitting is secured simply with a liberal bead of silicone on the flange faces where it meets glass, and then screwed up 'hand' tight. This is important with double base tanks, as you don't want to pinch the panes together putting added stress on them. If you do the fitting up too tight, the base panel, or inner panel may crack under the load.

Continue to the next page for more updates.