In my new 68g I have a nice big rock scape. 2 blowers with one pointing toward the back wall so I have good flow.. I don't believe there are any dead spots.. The tank is still newish and going through the typical stuff.. The diatoms have basically passed but I can feel bumpy stuff on the back wall but it's black so it can really be see ... I want coralline to grow so I was told not to cleAn the back wall and just let it be.. Only clean the front and side glass.. Is that really a good idea? I don't want bad stuff to grow.. The growth is so hard I would need a razor at this point so I want to just leave it!!