The next step in the build process was to start putting the main tank together.  The front back and side panes of this tank are made in 12mm, again, all with fully ground and lightly chamfered edges to keep things as true as possible. This also makes the whole build process allot smoother as you are working with completely safe edges. consequently the risks of chips and scratches, are also reduced as panels sit square to one another. However one of the biggest benefits of chamfered and ground edges, is simply an increase in bond strength.

This image shows how differing standards of glass edge, can effect structural strength. The pane on the left has a raw cut edge with a slight offset on it ( quite common without grinding ). This causes the panel to sit on one edge which separates the silicon bead 'inside' the tank from the main bond bead that the panel sits on. If you look at the ground and chamfered panel on the right. You'll notice that the silicon bond stretches across the entire width of the two faces and joins effectively to the inner fillet bond.

Having an inner base, besides adding tortional strength and rigidity, simply increases this contact patch. In this image, you can see that because of the 'v' joint the panel sits in, the contact patch is nearly doubled. Going 12mm across the base of the side panel, as well as 12mm up the side plus the fillet. Consequently, bond strength is considerably increased.

So, after covering all that. I called on the assistance of Mr Clark of 'www.Simons-Reef.com' to give me a hand working with the panels. I decided to paint both the side panels and rear, with three coats of  Dulux 'impact blue' matt emulsion prior to fitting them, and leave drilling the closed loop side returns until later on in the build. I always use emulsion because gloss paint can have a detrimental effect on any silicone it comes into contact with, softening it and weakening its bond strength. It is important though to ensure that no paint gets onto the joint faces and that they are completely clear of grease or fingerprints. so I always wipe down all panels and  joints with thinners prior to applying the silicon beads or any paint.

The following shots show the build process.

Mr Clark holding the front pane in position (whilst demanding yet another cup of tea...with two sugars)

I decided on a front pane in normal float glass, rather than the more optically clear low iron options in opti-white or starfire. It wasn't the extra expense that steered me away from this option. It was more a decision based on experience with photographing reef tanks. Personally, I've found that its quite difficult to get decent shots through low iron glass which I believe may be a result of the fact that it lets more UV and glare through it from powerful halide lights compared to normal float glass. I've found that this causes problems with many cameras giving a washed out appearance to shots. So in the interests of getting consistently nice photo sessions with a wide range of cameras. Float glass it was..

Just prior to fitting the front pane in place. a run of draught excluding foam strip was applied around the rear face of the opening so that it both cushions the front pane which will sit against it. and provide some degree of soundproofing as it limits any vibrations being transferred via the tank itself, to the wall it sits against. This also allows for a small amount of expansion on behalf of the tank without it pressing against the face of the tiles that line the tank room walls. On the viewing side, the remaining 3mm gap was filled with white silicone sealer as a final touch, and to prevent any splashes from running down the outside of the panel, and consequently  across the viewing pane itself. (sort of like a big oblong 'O' ring gasket if you will)

These shots show the tank with both, side and back pane on. Initially the front pane and side panes were assembled and left to set. and then the back pane was added last. The large baskets you can see in these images are the strainers for the closed loop outlets. Originally the intension was to use standard slotted tube type strainers. But after conducting a few tests with a friends newly filled tank and his sequence pump, it was noticed that a substantial increase in flow was seen if the outlet hole was left as unrestricted as possible (as much as 15-20%) . The only way around this was to cover these outlets with very large strainers that have grill surfaces well away from the main outlet hole. The overall surface area of these strainers is in excess of 3 times that of a standard tube type strainer made from 50mm pipe. This has two benefits. 1. They are safer in terms of protecting any animals that crawl over or get near to them as the flow through the grill is far more dispersed (this is especially important for tanks containing anemones). 2. The larger surface area, means that the strainers are less likely to clog too quickly. In my case, these strainers will be shaded and hidden under the rockwork, so this limits the amount of coralline growth that can cause problems over time. In effect they should cope for at least 2-3 years without needing any maintenance.

This shot shows the main tank set into the wall with all four strainers ( temporarily) in place over the outlet holes. The unpainted squares behind the strainers are there so that I can inspect behind and under the rockwork. Once in place, the rockwork will cover these openings so they cant be seen from the front. To prevent resting fish being disturbed by early morning light getting through these areas, they will be covered most of the time by two removable acrylic covers. At this stage, the inner fillets hadn't been done as the main joints were still setting. Afterwards the surplus (that squeezes out as the panels are pushed together) was trimmed off using a Stanley-knife blade, and all the joints were filleted to give a nice neat appearance. The final job on the next page, will be to add the brace bars and weir plate, and then trim all the surplus silicone to give the tank a nice, neat, professional quality finish.

What better way to spend an evening, than  with good friends, a nice meal, a bottle of wine, and a view of the reef right in front of you.

Continue to page 8 for the finale of the tank build..