but next to the windows getting sunshine, the T5HO bulbs don't even appear to be on
i expect many to disagree with this
sure, CO2 supplementation could help, ... but what is the line between bright enough to need it, and just simply bright ? i'm not seeing a need for CO2 and am doubtful if there ever is a need or just enjoyment of people who do supplement their tanks.
sunlight is still far brighter than the light fixture i have on the tank
and there's plenty of options to increase lights far beyond T5HO, ... even watts per square inch i could get an extra 50% intensity (maybe that will be equal to sun, dono, sun is definitely brighter than the lights i have)
new growth has not started poor due to excess light
new growth has progressively showed worsening nutrient issues
so i'm doubtful the lights are causing it.