Trying to increase the open usable volume in the cabinet. The two walls makes it hard to put a decent sump in it. The plan is to remove the two internal load bearing walls and replace it with supporting timber to carry the load. First pic is of what the cabinet is now, second is what i plan to end up with. Timber is ordinary treated pine 2 x 4 and 2 x 8 to span across the front. The two cross members are recessed into the main 200 supprt. What do you reckon strong enough? Should I use other timber? Diffirent support design? Tank is empty so now or never Chrs

Along the front where you have the 2X8, I wood change the 2x8 timber (to expensive) for a peice if 2x4 steel box or H iron if you can get it) and just put a peice of MDF along the front to dress it. Don't forget to paint the steel with something like PA10 before fitting. Just a thought.

If your not keen on any steel in your stand, your current design is good.

BSG

Thanks for that,

this is for a marine tank so with the corrosive environment I might stick with timber option.

Chrs

Is the tank 12mm glass, and well braced??my tank is over 1700x600x600x12mm and I have no support in the middle. I did a lot of measuring and testing when I filled the tank, but found the poly under the middle of the tank wasn't even under pressure and still moved so there was no bowing of the tank at all. The vertical glass front and back make the bottom very ridgid. I have the stand bolted to the wall and crossed braced at the other end so the stand cant colapse sideways.

Yeah, what Suphew experienced is exactly what you'll get with what you plan to do. The 200mm wide section is nowhere near as stiff as the front glass section of the tank. The weight near the edges of the stand will deflect the centre of the stand downwards so very little or no force will be taken by the stand and most all or all will be on the front glass. This does weaken the glass a little but should be fine. There are many tanks that are only effectively supported on each corner of the tank due to very flimsy stands.

Removing the centre support seriously weakens the support relative to the original design. You could consider adding removable front supports so you can fit a big sump but still maintain excellent centre support by using the floor to take the centre weight... Then you won't need the 200mm wide section that does very little or nothing anyway...

What you have on the second plan is very good. As a cabinet maker the only thing I suggest is that timber has a grain, which means it can have movement along that grain. I'm not sure if you are familiar with a bulding product called hyspan or hybeam, this can be used instead of a floor joist or beam & it is made with 17mm plywood on its edge & 50x25 timber top & bottom for fixing to. Plywood on its edge is as strong as a much larger sized timber with out the potential to movement along the grain as the grains are laid at 90 degrees of each other. The only thing to be careful of is stopping the vertical plywood curving. Let me know if you want more info.

Smidey

Thanks that really helps.

The glass is 10mm. Point taken on the 200 front piece. I will make 2 removable supports and probably reduce the 200 piece to 150 or so and look for the Plywood type products that i can see would have a greater stiffness. I have a feeler gauge so will be able to measure the deflection.. if nothing else it would be interesting.