It won't harm em' if you don't apply it to anything but the aptasia.
I forget exactly what it is, but you can just buy the chemical as well if you want to save some money, it comes with a small syringe applicator - just turn off all powerheads in the tank and put it on, it sticks to the aptasia so you can turn em' right back on.
I've had a little bit fall onto ric's before and nothing happened. You just can't over apply it - kills the aptasia in like 30 minutes.
They make some through Red Sea called Aptasia Control or somthing that's cheaper, too.