I keep my temp around 81-82 , but keep in mind the higher the temp the lower the O2
. I've also read somewhere not 100% sure about this that a lower SG
is ok for short term but long term is not good for the fish digestive system.
Also read that Garlic is not a 100% guarantee that it will work against ich but some people say it has worked for them and stimulates the appetite also.
The only way I deal w/ ich and have dealt w/ it 1 time is let the fish immune system battle it. Keep them well fed (Nori) and as long as they keep eating they should get over it. Slightly higher temp wouldn't hurt to speed up the ich life cycle. And I also did 10-15% water changes like every other day to vacuum the substrate and rocks to catch some of the eggs and parasites that might of died off. Keep the water quality crystal clean and only keep lights on for a few hours.
From what I heard ich likes to travel upward towards the light to find it's host. Keep the tank as stress free as possible.
Just my 2cents.