
This is pvc, torched, bent and a little dremel work. Torch it till it bubbles and get even more texture. Once it is to this stage, paint it and drop it into the tank...pvc sinks.
This image is from a website I can across but I have done this before....just no pictures. I will try to make one and post later.
This is so easy its not even funny. You cannot make mistakes...mistakes make it even more realistic.

That is way better than anything I could have imagined!