im making an overflow and i have a question. will the flow rate be affected if at the T i have an about 3ft pipe going straight across to the other side of the tank before it elbows down to the sump? if this is confussing ill try and get a picture
The energy potential within the pipe might be reduced so flow could also be reduced. You may not notice it at all though. Sharp 90* bends hurt the flow even more and you can sometimes notice that. 90* bends with a large radius could help.