Depends on what you want it to do, dose over time via yoru controller or do you want it to do it all for you? The BRS drews pumps work well and are $ friendly if you have a good reliable timer system or controller. Litermeter are nice, I use em, though I just plunked down for a vertex to replace it. Also what volume you looking at? Size of tank, that matters since if you are dosing a big tank you want a reliable system.
