why do you want to add purple up? There's no need for it IMO. nobody doses the ocean with anything... I never add anything to my tank like that... no sirreee... It's not natural. If you want your coraline to grow faster, check your calcium levels. If they're ok, it's probably because you don't have enough lighting. If you want your coraline to grow faster, scrub a little bit of your existing coraline with a toothbrush. This will cause it to release spores, and therefore it will spread faster.