It's relative to the amount of nutrients in your substrate. If there are not many nutrients in the substrate then very little will be added to the water column when the substrate is agitated and vice versa.
It also depends on your photo period, the longer and more intense the photo period is, the likelier it is that an algae bloom will take place.
Define constant ? If by constant, you mean daily, There will be a likely hood that your biological will have adapted to the higher nutrient levels in the water column and consume most of the nutrients. If your tank is chugging along with little nutrients in the water column and, suddenly, a large influx of nutrients is released into the water column, the bacterial filter can't possibly consume all the nutrients and algae will take over the task of consuming the nutrients.
All this is assuming the tank is well established. If the tank is new, there will be very little bacteria or algae available to consume the nutrients and therefore it will not be noticed until the tank becomes established, then all hell breaks loose and you'll get a bacterial bloom, if your lucky, or a serious case of green water.
FILSTAR Pimp #2
75 gal heavily planted,50/50 Black beauty,Eco-complete substrate, Pressurised CO2 with solenoid, ph controller, AB Reactor 1000, 330 watts 9325K GE PC lighting,Ehiem Liquidoser, 2-Filstar xp3 canisters.