I dose with malachite green medicine. I used Rid Ich. Dose for 0.05 mg/l, and do it every other day, for 3 doses (so 6 days of treatment). For my 55g tank, at teh concentration of malachite green in Rid-Ich, this worked out to 12 drops per gallon (note the instructions say 1 drop per gallon!, this is way too high). U turned my temperature u p to 82 degrees, which gives the ich parasite a life cycle of ~3 days. You can only kill the ich when it is free swimming..the meds don't help when the ich is encysted on the fish.
Purportedly, if you dose at 0.05 ppm (mg/l) you shouldn't see adverse reactions in any of your tank inhabitants. For my part, I can say that using that dosage, cherry shrimp, nerite snails, trumpet snails, cory cats, clown loaches, and synodontis cats showed no signs of stress or ill effects. And it did not kill off my filter bacteria.
Most tank meds are oxidizers (they use up dissolved O2 in your tank) so it is important to add a bubbler and lower your water level if using a HOB in order to facilitate O2 uptake in the water. Malachite green is also photodegradable so turn off your tank lights too.
It did turn the coarse sponges in my Fluval, and the silicone sealant in my 55g green/blue, but that was the only adverse side effect that I noted.