Dosing for controlling

Hey Reefers,

I've been having an algae issue recently and I was wondering if I was to put Kent Marine Iodine in my tank would that help the purple algae to grow instead of the brown, red, and green algae? Almost all my rocks have some coralline algae on it. (if not a lot)

Also does anyone dose Calcium? I've been told just supplement it with salt.
And does anyone dose Iron? I've been told also to just do water changes with my reef crystals salt.