The white stuff on your rock more than likely is the calcified skeleton of dead coraline algae. Most ppl wire brush it off before the curing process.
Best way to do water changes - I'm sure theirs a ton of them. I have a w/c tank with heater + powerheads and an ro/di unit. I fill up the tank with RO add salt let run for 24 hours to stabilze ph and temp - test and add til 1.026 - waters ready. I have a utilty pump in the basement that pulls 10% of the main tanks water weekly to the drain and a mag drive 7 pump that fills the main - I HATE buckets, too labor intesive for me.
Best way to do water changes - I'm sure theirs a ton of them. I have a w/c tank with heater + powerheads and an ro/di unit. I fill up the tank with RO add salt let run for 24 hours to stabilze ph and temp - test and add til 1.026 - waters ready. I have a utilty pump in the basement that pulls 10% of the main tanks water weekly to the drain and a mag drive 7 pump that fills the main - I HATE buckets, too labor intesive for me.