Diy 3d Background Need Suggestions Please

[t4ppo]

Right so after shutting my Marine tank down a few months ago, and going back to tropical due to time and work etc etc etc,

I know have more time on my hands than I know what to do with it again! So I've decided im going to build a 3D Background, I already have a shed load of polystyrene and can get more if needed, I have a 5x2x2 Tank which is sumped,
Now my plan is to build the background out quite a rocky looking shape, In one corner I am going to have like quite a big cave sheltered from the lights using an over hang which will be attached to the sill on the tank, Which will mould into back and side walls Its going to be both sides and the back which are 3D,

Now this is where im stuck for ideas.. I have a central wier Which is fairly big so I Dont want to move the weir and have two corner weirs as I Dont feel comfortable drilling the tank and to be honest its a lot more work than I want to do, So im not sure what to do in the middle,
I Dont want just a wall which follows the back of the tank all the way along then round the weir etc, I want to "Try" and make a feature in the middle, Also it has like a horrible mirror effect on the central weir and it has got some brown staining on it which looks awful, so I want to cover that up!

Any ideas or suggestions would be great
When I start this project I will be creating a journal too!

Heres a pic of the tank to get an idea of what its going to be in:

 

[ColR1948]

I made a couple of 3D backgrounds with Polystyrene, One I put inside the tank sticking to the back with aquarium sealant.
The other I just stuck to the outside, it still looks good though.

I shaped it by putting a wallpaper scraper over the flame on the gas stove, letting it get hot then marking the the polystyrene to make it look like rocks and crevices, also seal the edges with the scraper or knife to to stop the bits from coming off.

It will float as you know so fixing it like I did was with aquarium sealant or you will need to fasten it to something heavy, it will lift large stones so sticking it down might be the best option.

 

[Aquascaper]

Only thing I can think of doing with the weir is creating a scree slope around it with actual rock. This would hopefully help your 'fake rock' background blend in a bit better?

 

[t4ppo]

Only thing I can think of doing with the weir is creating a scree slope around it with actual rock. This would hopefully help your 'fake rock' background blend in a bit better?

Yeah sounds like a good idea, it's a pain having a central wier wouldn't be a problem if it was in a corner,
Another idea I have had, is to build say a tree trunk out of polystyrene and have that around the wier with a few roots coming out going into the substrate,

 

[Aquascaper]

Nice idea, you could maybe even find a real one?

 

[t4ppo]

Nice idea, you could maybe even find a real one?

And what cut the middle out so it fit around wier? Also would it not rot?

 

[Aquascaper]

I've seen bogwood like hollow trunks before. It will rot eventually but not for many years. It does affect water parameters though by lowering pH so might nit be suitable depending on what youse planning on keeping.

 

[Liz xty]

What paint do you use on your DIY polystyrene backgrounds?