Was just wondering because since putting them into their new tank with light, they seem to be alot lighter in color. Maybe it is just the light playing tricks with me eyes.
I ususal keep the light on @ nite and off during working hours, honestly never heard of GT's requiring "darkness". They are day-feeders not nite feeders like most characins.
Higher Temp's do not prevent disease nor algae - weekly water changes and quality prepared foods are the best defense against disease. In case of an infection higher temps speed up the metabolism of disease creating a shorter life span for the outbreak. Avioding direct sunlight and not overfeeding is the best defense against invassive algae. Marco and micro algaes are benificial.
IMO 80 degrees is good for juvie's helps them metabolize faster promoting healthy growth - however higher temps as adults will increase fish activity hence increase aggression w/ aggressive new world cichlids. In my case I have several species aggressive new worlds so lowering the temp to 76 keeps the confrontations to it's minimal. ( minimal for my fish is they don't kill each other but still fight from time to time )