The problem is that even with the distiller...there is about a 35% chance that you won't get the spheres that you wanted out of the monster. Well, i hope that you enjoy posting and have fun gaming.
Yeah, the bad thing is that it's hard to tell if it's working or not so if you really want to get Mana spheres through that route(there are other ways) then i'd recommend using a couple distillers on monsters just to make sure that it'll take effect(or so you'd hope). The best way to get Mana spheres are to fight one of the types of Flan's(ie...Thunder, water, snow, etc.). Go to the Monster Arena after capturing one and then you can fight them right there just to get the Mana spheres. A very easy way to get these spheres indeed. Well, i hope that you enjoy posting and have fun gaming.