the red dots are t-valves. in order to empty water, id close valve 2 and open valve 1. once done id return both valves to normal (open 2, close 1) in order to add new water, id close 4, open 3...this would essentially cause the pump to pull water from the new bucket, and pump it up into the tank. add when done, id return them to normal (open 4, close 3). also I know a lot of people were going to say "you shouldn't throttle your pumps at all" or " you cant attach elbows on the intake side of a pump" which is why, if you notice in the picture, the t-splits that are going in, will allow straight flow for the main plumbing (the lines running back to the tank. and the line running into the pump. also on the intake side of the return pump, itll be a y-pipe, not a t. as to eliminate any throttling. this way all I have to do is lug the water up from my basement, flip a few valves, and tada!! water change is done.
***edit*** I may even run a hardline out my window for the drain line, the tank sits right next to the window so we shall see.
