Pretty much what I'm thinking, I'm just concerned with the horizontal span. I'll have 72" of unsupported span, which according to that link will be fine, but I'm not sure I'd sleep well :)
Maybe an additional vert in the centre will give me peace of mind, without restrciting access too much.
Changed my mind on the sump, I'll use a 75g instead of my 115g, which gives me an extra foot...

Brad - just remember the weight of your tank is distributed throughout the span of the beam. If you're still really nervous, double up the 2x6 horizontal beams on the front and back. I did a 6' tank as per link and I've had plenty of sleep since :)

Thanks Chin, I guess you're right, I wasn't looking at weight distribution properly :) I may double up the 2x6 horizontals, that way I'll sleep too

Brad, if you're concerned about the horizontal span, order a glulam from Rona or somewhere. That's what I'm doing for my 8'.
Much stronger, no crowns, twists, warps.

Mitch

Mitch has the right idea. Composites and laminates are great for important structural components (like long spanning unsupported beams). Regular lumber is subject to grain and knot imperfections that create weakness. Of course you can always just beef up the lumber, but then you're losing valuable opening space into your sump area. I built my stand out of 3/4" oak ply, solid panels all around taking the load with a double-thickness laminated front panel that was cut away to allow access for sump etc. The laminate nature of the plywood with alternating grain direction make for very strong parts. I've got photos and solid models I can share if you like, but my particular design probly won't help much as it was designed for a tank that's 30" x 24" x 24". If I were doing a stand for a tank as long as yours I would design it with a support mid-span (front and back) and make the front support removeable. I have seen clever ways to take the load off the front-center brace of a stand while a sump is being serviced with a full tank still in place.

From a thread on RC, spanning 6 feet with a 2x6 won't require a vertical support mid span. So my design is a top rail of 2x6 on 2x4 verticals (2 each corner) plus additional support on the outside corners, as I'm making the stand longer than the tank. Then sheathing with 1/2" plywood, so strength should be fine. Not crazy about 6 inches on top, since it will block access to the skimmer cup a bit, but not a huge deal.

We built ours using much the same design, but added a piece of plywood on the bottom. It kinda helps distribute the weight evenly on the floor AND we siliconed the joints and painted it with a couple of coats of marine paint. If we had a leak or overflow it would hold a few gallons of water without soaking the floor.

Exactly my plan. Then I have to figure out how to level it, the floor isn't exactly flat :)

go to HD and buy those plastic shims for leveling doors. work great! once the weight is on they wont move.

Here are a few shots of the stand I'm building right now

http://i461.photobucket.com/albums/q...k/PA180030.jpg

This cabinet on the side will have a hidden door that will house all my electrical
http://i461.photobucket.com/albums/q...k/PA180032.jpg

http://i461.photobucket.com/albums/q...k/PA210041.jpg

Tonight I'm install all the junction box's and routing all the wires.....and with any luck I'll get a chance to start skinning this week end
http://i461.photobucket.com/albums/q...k/PA210040.jpg