Great tank, I would up the temperatre to 82 deg f, use 1ml of ws3 for 1 week then do a 20%
water change. Monitor your fish and if it appears ich is still present, then repeat for another week and then bring the temperture gradually down to 79 - 80 deg. Alternatively you can use methylene blue, but.. it stains the plants, seals and decor... although I found it does wear off the plants after a week..
As shawnie says, adding an air stone is required if you increase the temperature, warmer water is less oxyginated.
Might be a good idea to get your self a small 25 - 50 litre tank to use as a quarantine tank then you can place fish into this before introducing to your main tank.
also, always acclimatise first, i.e. leave in bag for 25 mins or so until its same temperature, fish can show a similar looking effect from putting the fish into much colder water than they were living in which is why acclimatisation is a must!. And never just pour the fish straight in, the shops water may be infected! which I have seen in the past.
Anyway, good luck.. I am sure you'll sort it out

we've all been there..