Hi there,
personally would not use the structured backgrounds as I had a real bad experience. I have juwel trigon 350 and i fitted it with juwel structured backgrounds and I had a breakout of brush algae, I tried to clean it but it made them break up (they are made of a polystyrene substance, i know its not but has the same texture) Don't know if this has been made with a different material now, it was 5 years ago.
Anyway, as I had siliconed them to the inside of the tank, I had to drain and re-home the fish, then with a blade take all the silicone off....it was a bloody nightmare, but I had to do it as it looked terrible with chunks missing from it and bits of backgrond floating in the water then wait ages to cycle the tank again!!!! An exspensive mistake to make!!
Also, I found that some of the fish used to eat at it....don't know if it is harmful to them...can't be good for them though.
It always looked horrible as no matter how hard I tried to keep it clean it alwats got yucky stuff at the edges/corners, this could be solved by not making the strutured background go to the edges/corners but this would look crap or risk damage to the silicone that holds the tank together when you try and clean it!!
I suppose the question is; Do you clean them out regularly without question?..... then you should have no problems, but i would never use it again, personally I would use backing paper and vaseline or paint the back (outside)...I have painted mine turquoise using special paint and it looks really good!!(do not use regular paint as the fumes can cause damage to the fish, even after it has dried)
Hope this helps...this is my view, anyone else have any opinions???
Warm regards,
Emilie x