After the sump assembly was built, and the DSB was up, running and maturing. My attentions turned to finally building a stand for the tank to go onto.

Originally way back when the initial thoughts for a separate tank room had crossed my mind, I had considered another wood built stand. But after thinking a bit more in-depth about what I needed to fit under the tank, and the problems involved around working round several support legs etc. I thought 'what the hell, why not get rid of the legs altogether and have a completely open area under the tank. To do this I needed a very strong and stiff method of supporting 1271 kg of water or about 1.3 tonnes.

To that end, I decided on a two column support, using steel RSJ's as the cross members to sit the tank on.

The first job was to build the two support columns. For these, I used normal concrete blocks available from B&Q. (please note, you should not use light weight breeze blocks for this type of construction, as they fracture easily under load, and have very limited compression resistance ). After  marking out the floor where the support columns were to be positioned and measuring diagonally from corner to corner to ensure a square build, I started laying the courses using a 2-1 sand cement mix. Its imperative that when building any support columns you check each and every course as you build to ensure the courses are level and true, both along the run and from side to side. Equally, you should check across the supports to ensure you are not running out as you build upwards and that you are level across the two. (small differences are permissible from course to course as you can always level off at the final top course. its this one that's the most crucial ). The stresses placed on a twisted tank holding up 280 gallons of water are tremendous, so don't take any chances. If you feel your final course isn't quite right...rip it off, and do it again until your 100% sure you are square and level in all directions across the two columns.

(These two shots show the beginnings of the support columns and the final result. (it may look as though they were built on top of the laminate flooring, but they weren't, The laminate was laid after the third course, in preparation for the skirting to be fitted around the room.

At the top of each column was a solid concrete lintel made from a 2"x 8"x 42" edging stone. this disperses the load of the RSJ's and tank more evenly across the top of the columns, especially the outermost RSJ that rests on the 'end' of the column.

In these two shots, you can see the end of the lintel which is surrounded by a fillet of cement to hold it in place on top of the column. In the second shot you can see the three RSJ's resting on the lintels. RSJ's must be placed as shown, and not on their sides. Rigidity comes from the profile of the beam in a vertical position. If it was laid on its side, the beam would sag in the middle causing the tank to sag and the base to crack.

In my case I chose beams with a profile of  3" wide, by 6" high. They were pre painted with red oxide anti-rust paint, 'three coats in all'. When placing the beams, a thick pad of silicone was put onto the lintel first and the RSJ was pushed down onto this to ensure a good bond with a small degree of cushioning.

In the first shot, you can see the underside of the beams and how they rest on the lintel. And the second shot, shows the now plastered support column, (note there is a hole left in this column near the bottom). This allows me to run plumbing through for the RO feed to the sump float switch, and for plumbing  lines through to the water change tank that will reside between the two columns.

After all that was done it was time to start thinking about the interesting stuff, i.e. getting a base board down, Polystyrene cushion board, and the tank bases in. To do this, I decided on a single 6.5' x 3.5' sheet of 25mm marine plywood for the base, and a 1" thick sheet of polystyrene for the cushion board. Many of you will be familiar with using polystyrene cushioning around the 5mm mark for average tanks, but be aware, that with the weight and lengths involved with big tanks and the propensity for a small amount of bowing, you need to think bigger and thicker. This allows any minor indiscretions to be soaked up in the thickness of the cushion layer.

Continue to the next page for details of the base section and first glass installation.