Recently did a water change with tap water and cut 2 power heads off for about 2 weeks so that a mushroom could attach itself. BAD DECISIONS! I'll tell you why.

1.)Tap water is basically food for algae. Water treatment plants add phosphates to the water so it doesn't corrode in pipes, in turn the algae feeds off of the phosphates in tap water. So use RO/DI water if at all possible.

2.)Red Slime Algae (Cyanobacteria) doesn't like high water flow rates. I cut off my 2 largest power heads reducing my water circulation by around 1200 GPH.

Now I have to deal with a large scale red slime algae attack.

That sucks! sorry!