I also have a vertex Libra doser that does the 0.5ml doses, but find that it really is more of a gimmick. Dosing anything less than 1ml with a doser is almost pointless. I find it's easier to dilute my dosing material to match the pumps ability. As an example I dose 6 ml kz coral snow daily. Now if dosed at once it makes water cloudy. By dosing 1ml at a time I'm at 6 times a day. So every four hours. I dilute by half so I can dose 1ml every 2 hours, and avoid all clouding. The ghl is by far a more reliable unit, and profilux integration is important enough to make a small no pun intended sacrifice on dosing minimum.