Three question: Nano, Fog horns, and...

[thomasina]

Read it all the time, but have no idea to what it means. Then there is something that folks have in their tanks that look like fog horns. One is pointing right, the other left, what are those? One more ??? What is R.O.A.K. mean?

 

[bevoholic]

I'm not sure what the horn things are. They might be the inflow and outflow pipes for a canister filter. ROAK means Random Act of Kindness.