1800 Gallon Tank

Started thinking for my next project. Have to finish many other things on my 99 Gallon, but it's fun to get plans ready.
I hope to start with building this somewhere March next year, nice time to get some feedback and ideas.
The tank will be outside, under a roof that's Poly-Carbonate (tinted) while on top of the tank there will be another small roof that will also house the lights and fans. (fans for cooling down, temperature is around 30 - 35 Celcius year long).

- Tank will be Amazone setup, thinking of Arowana's and other fish that can be kept.
- Low maintenance, so only drift-wood and a 3D background of concrete and epoxy, course gravel bottom.
- measurements (LxHxW) = 2.5x1.8x1.6m and filter of 0.5x1.8x1.6.
- 2 pumps that push the water through a series of undergravel spray-bars. (This would help me keep the gravel clean and push all dirt to the surface and in the filter.
- Filter will be a course filter mat, then jap-mat and finally a lot of bioballs.
- Filter could be adjusted with another layer of ceramic rings
- Then through the pumps back in the tank.
- Filter and tank side by side, so no problems with overflow/power-outage and other sump problems.
- Tank to filter with shower-drain type of fittings.
- Front of tank facing the terrace and lights, just simple strips, enough to light up for viewing.

My aim is to have a setup that would require only water-changes and replacing or cleaning the top filter-mat for course rubbish/waste.

Below two pictures to explain it.

Construction will be wood and glass I think. Need to check on prices for glass.
Concrete slab as foundation. Currently it's a small strip of plants that will be removed.
Some work to be done on with taking out a tap and changing the water-pipes running there.
Front of the filter will also be glass to keep a good eye on things and maybe cover it with a wooden access door covering both pumps and the glass viewing window.
Top of the tank and filter covered with a frame and net to avoid happy jumpers.

Fish: Arowana....please post your picks for stocking that goes with it.
Background: I've done a concrete/foam background in the 99 Gallon, works out very nice and want to do something similar in this tank.
Bottom: course gravel, maybe 2-3cm minimum size gravel, color brownish.
Drift-wood: Big tree-stump or otherwise 'dramatic' pieces of wood.

Plants: Initial setup, none. Might change that in due course if possible, but then it would be attached to the driftwood if possible with the choice of fish.

Another scenario would be to stock it completely with small and medium size fish, hundreds of neons and other small amazon-species, but it has to be a specific Amazon tank.

Would like to see some suggestions there, plants would need another setup all together with higher light and CO2, but that's an addition that can be made easily.
Covering the sump to avoid CO2-loss will also be easy.

For the glass, will check the forums to get an idea, but guesstimate that it will be a 3-4 cm thick slab. Hope it doesn't break the bank.

Wood will be the normal suspect, probably 2 layers of 2cm thick.
Covered with epoxy and fiber matting in the corners.

Frame of 6x4'cm and metal corner pieces.
Isolation and outside layer of wood to keep the heat out.

the 6x4cm frame is a bit confusing. Wood at corners and base should be way bigger of course. Will get down to study on what it will be exactly later.
Wood is not expensive here, so overbuilding will be the norm.
The location will help me use a concrete ledger with a pillar in the 2 backside corners of the tank to support it. Lots of paint to protect it for a long time to come.

Well noted JRR, I'll spend the coming months looking at all options.
My gut-feeling tells me that glass would be the cheapest option in Thailand, but that needs to be backed up with some research on it.
1st priority is safety, so glass might drop off the list, but not 100% sure on it yet.
So far, my other tanks are glass and I like it, but it will take some time to decide on it.

That's why I started early and will slowly put all the pieces together.
Building the tank will be such that I can finish everything inside, using the 'window' to get in and out.
Then final touch will be the glass and filling it up.
Pumps should be two heavy-duty waterpumps with some power-control. There's also be space for electric, switches and others. Much to be decided yet.
Sure is that the tank will be one piece, filter 'build in', to give a nice and clear view.

Check my thread on the 99Gallon to get an idea of the background and materials used.
http://www.aquariacentral.com/forums/showthread.php?t=177028
Then you'll also know why it will only be next year to start this build at the earliest.

Here's another more frontal view of the tank:

I'm getting ready for my big tank! Basic idea as per previous posts. Initially I said 1800 gallon, but that's a bit optimistic. Outside dimensions yes, but take out 10 to 15% for the walls and you'll end up at 1500 to 1600 gallon. Still big enough I'd say..
Attached a picture of the place for the tank. Due to conditions here, I'm not going to take any risk and use concrete and/or concrete blocks to build the tank instead of wood. Front will be glass or acrylic, need to check the prices here locally.

Back and side of the tank will be concrete shaped 3D similar to my 99 gallon tank.

Coming months I'll use to collect information, make more drawings, get quotes from my contractor. Basic list of work to be done, though there's still many parts open to revision based on input from you guys:

1. Remove the soil and tiles.
2. Change water-pipes
3. Piling, likely 6x 3ft deep.
4. Rebar for first floor-layer, connecting the piling.
5. Poor first concrete layer. Basically a slab to start the actual tank.
6. Rebar and drilling of holes in the existing concrete pillars and walls.
The idea is to poor the back and side wall against the existing fence
(which is steel with cement-board.)
7. Rebar for the actual tank floor
8. Placing wood cement-forms.
9. Put over-flows and returns in.
10. Poor cement.

Once the structural work is done, there's a list of things to do. To avoid any trouble at all with termites, most of the construction will be done with cement-wood on the outside and for cover of the tank. This stuff is super strong and long lasting.

Filter will be next to the tank so there will not be any issue with overflowing/running dry after power-outage etc.
For sealing it, I will likely go with epoxy resin.
The viewing window will be seated in the concrete opening for it. I plan on something like 2 inch of concrete to hold the window in place with silicone to seal it.... The idea is to have the window flush with the inside of the tank.

I like to know more from you guys on following:

1. Thickness of the concrete walls and for the rebar to be used.
2. Floor thickness.
3. Thickness for Glass or Acrylic window (size 160cm x 140cm or 62" x 55")

Look forward to get some input and ideas..thanks for reading.