algae or bacteria?

[bigfish]

i started my tank in may so its a new tank. i'm going to do a 15% water change and try to siphon some of it off and feed a bit less.

[fragNplug]

yes thats known as red slime algae, but it really is a bacteria.
You can siphon it out of the tank, and reduce your light cycle.
It tends to grow where there is little current, and high nutrient deposits
Large Temperature swings will also make it more likely to grow.