once my lights go off in my tank my p's go mad...they swim up and down and all around..i hear them as they crash into the sides of the tank or they rush up for air adn knock on the light..i think they just feel more comfartable and secure without light..
Mine do the same thing as yours Mad now that they're in the 180...I think he may have to do with them having more space to themselves since you downsized and since I upsized my tank. Yours(as far as I saw) and mine always were huddled together but I think they felt a little cramped up...and now they have more room they stay together but take advantage of that room. Not sure about the time frame part of your question though, sorry.
Same here, spilos are no different. They cruise the front of the tank back and forth, up and down. I can see thier shimmering little bodies from the light of my computer right now going back and forth. I just figure that it was natural since all the lights were off around the tank, and that P's feel more comfortable in the dark.
all of my reds have done this they line up and swim from one side of the tank to the other .i have my powerhead pointing toward the back of the tank and they take turns swimming into the current .
i also think it is due to having more room to roam and show this type of behavior