Diy Tank Stand - Help!

Im wanting to make my own tank stand because I need to condense two 6ft tanks into one space.

I have my newish tropical tank and a turtle tank. Im going to make a stand that will have the fish tank ontop, with an overall height of just over 6ft, and my turtle tank underneath. The weight of the top tank I have estimated to be 340*Kgs including water/substrate/ornaments and the tanks combined weight.... but I want the lower tank to be fully visible without a centre support.

IVe added a very basic paint drawing to show how I want them setup. So my questions are;

What is the best method to create a stand capable of holding the combined weight of two very big tanks?
How can I do it without having a centre support in-front of the lower tank?
Also what wood and fittings would you recommend?
Would the combined weight be too much for the floorboards?

I think OM and some of the others here have made their own stands, plus be sure to do a post in the Hardware section. WD

As WD said, many of us here have some experience building our own stands. I have a thread of my own in the DIY area that sets forth some of the considerations that I used when designing my own stand.It is far from a perfect design but may give you some ideas to consider while designing your own stand. My thread can be reached from a link in my signature area or here. Either way I look forward to how you go about designing and executing a new stand design. I am always ready to learn from someone else's experiences whether or not you have any success. Even a failure has lessons for the rest of us.

I've made 2. One use the walls either side for the support. The toher is free standing:

FREESTANDING

WALL SUPPORTED

AC

I've made a 3 tier 6ft stand using 2 x 4 timber that does the job.

Pic: