They are fairly easy as far as anemone goes. Just clean water, stable condition. IMO, if you can keep SPS thriving you can keep H. malu. They do need to have about 4 inches or so of sand to bury their foot into. Light wise, I keep them under MH. My anemone is about 16 inches or so under a 250 W DE MH with very good reflector that essentially direct all the light back into the tank, so it is very bright.
I change water frequent about 1/3 every month or so. I don't check my water chemistry and added Magnesium, Ca and Bicarb Per formula (Bulk Reef Supplies). I added Mag first and then Calcium. When I add Bicarb, I can tell by observer how the cloudiness disperse, I can guess how near saturation the Ca and Bicarb is. By experience I know how much to add and have not overshoot to cause white out tank in the last 3 years. How I keep my tanks is not a method for a beginner, it took a lot of experiences. I keep saltwater aquarium since 1980 and reef type aquarium since 1988 or so.