Loaches easily get ich, and easily recover from it... Raise the temperature like catfishmike mentioned, but I'd avoid the medications, clean water and salt would be my cure (I use about double the recommended amount, which I cant find the box, think its 1tbsp/10g I could be wrong). Just remember, salt doesn't evaporate, so every 3-4 waterchanges add some back in (not the full amount) adding a capful of melafix at each water change doesn't hurt either.
Waterchanges Waterchanges Waterchanges. 20%/day preferably, make sure you're taking the time to clean the gravel while you're doing those water changes.
Remember all those clown loaches are going to get WAY too big for that tank, I've seen pictures of 20" specimens!