Help!!! Ick!!!

[Ruth]

I think the only sure fire way is to take them out of the tank into a quarentine and treat with hypo or copper. Leave them out of your tank and let the tank go fish less for 6 - 8 weeks which should be enough time for the ich parasites to go through their cycle and with no host fish they should die out of your display.
There is no proof that garlic helps but MY theory on it is that it does not hurt and actually seems to entice fish to eat more thereby making for healthier fish that are better able to fight disease and parasites.
There is no reason that you cannot have your lights on while your tank is fish less as the ich parasites do not care if there is light or not. They need a host fish in order to reproduce so your corals will be fine and just keep your regular lighting schedule.
OTOH the ich parasite can and does live in many of our systems it's just that our fish are healthy and able to not let it take over and are able to fight off any infestation of them. If you add a new fish it may be weak from shipping or whatever and is likely to become infected.
This is just my 2 cents worth and based on my own experience.