From my understanding, all living organisms uses phosphates to some degree and it follows any food you add to the system will have phosphates bound up in it (whether it's listed on the label or not).
The more animals and plants you have living and growing in your system, the more phosphates get taken out of the water column. Problems arise when there is too much phosphate getting bound up in the coral skeleton that's when it starts to affect tissue growth
....some phosphate good, too much very, very bad
