Originally Posted by sherry
Plantbrain's answer to me when I thought old bulbs were causing my algae was simple : less light doesn't cause more algae.
Old light bulbs = shifting of the light spectrum
shifting of the spectrum = less light useful for plants
less light = slower growth and sheading of leaves
slower growth = build up ferts in the water column and lower consumption of NH3
sheading of leaves = more NH3
and organics in the water column
more ferts and NH3
in the water column = algae.
This would depend on how fast the light bulb changes the spectrum. The slower the better. ie the bacteria have a chance to catch up with the NH3
in the water column.