Treating Ich, Help Needed

i have recently added 6 5 banded barbs to my tank and hey presto, 3 days later i get an outbreak of ich.
the other tankmates are marbled hatchets, ottos ,black neon tetra and agassizi dwarf cyclids. plus one dwarf gourami.
not all of them are showing signs of ich but i intend to use heat treatment only as my tank is heavily planted.
any advice please? i am worried that not all of the species will make it through 2 weeks of high temperatures and i do not have a spare tank or space for one.
can anyone recommend a plant safe ich treatment please?

I'm using EXIT right now because it's also supposed to be invertebrate safe. My problem is that you're not supposed to use water conditioners with it and I have used aqua safe dechlorinator because I don't see another way of changing the water without damaging the fish.
My lot are now into the last day of the extended dose but, to be honest, I don't see much improvement  -  though the snails are happily trundling about and munching.

I may just have a particularly resistant strain, but I would've thought the spots and everything would be gone by now. I know that's probably not the most positive review of this med, but others may have some better advice for you about EXIT 

The spots do drop off the fish as a natural part of the life cycle. Exit claims to be able to kill the bug while on the fish; as far as I'm aware none of the other ich treatments can do that. With them it is very important to continue treatment after the spots have gone but Exit seems to be different.

Good idea on emailing the company  I do know that there are some products, not ich meds, that don't work properly if there is an ammonia detoxifier in the dechlorinator, maybe Exit is the same.

Carbon does indeed remove the medication. Leave it in there for 48 hours then bin it - together with all the med it has removed. And doing a water change first removes a lot of the med leaving less for the carbon to grab.