Originally Posted by
stunreefer
Too long, not so much (it will just "fill up"), too much, yes. You can drop PO4 too fast and bleach/kill/harm coral. This can be caused by too fast of flow though a reactor as well.
It's best to dose small amounts throughout the day (never Ca and Alk at same time though), but this is only practical with an automated doser. When I dosed by hand I would do 1/2 of the Alk dose when I woke up, followed by 1/2 the Ca dose before I left the house (after shower, brushing teeth, etc. - in other words a half hour later or so). When I got home I would do the other 1/2 of the Alk dose, followed by the Ca a half hour later or so.
Make sure to always dose in a high flow area (in the sump if possible to prevent contact with coral).