How much of a drop do you see when hand doaseing every fourth day ? What brand of Mag are you useing ? there are stirers on the market or you could use a nano type power head to keep it stirred up. I use to use kents teck M but with no reral algae issues present in the system I have since switched to BRS's mag and automatically doase to maintain a level of 1600 to 1650. It mixes up clear and their's no sediment to worry about. Food for thought.