little confused (my DIY aero)

so ive got it mostly taken care of, the PVC H bar type in a plastic 20 gallon tote, 400 gph pump, 8 red misters, blah blah... anyways....

so ive read as many DIY aero setups as possible, but i cant seem to find where anyone explains the res changes, im working with a closet. I need a way to do it somewhat easily. If i used the water level indicator, id have to raise it up high enough to drain into another res then carry it outside and dump it... anyone know a better way?
thanks

when i first built one, i use it now for cloning, anyways i was short on ceiling space, stink bud's method stacks 2 rubbermads, so the top chamber has a sprayer setup with roots hanging in air while the runoff drains into the lower rez, this is clearly the easiest,for me this was not feasable, so i got 2 rubbermades and just when i needed a fresh rez, i filled the empty clean one, dragged it to my room, popped out the sprayer manifold and dragged away the old water, this way i had somewhere to put my lid with all the babies hangn in it, i believe with those thin walls trying to drill a drain into it would result in a catastrophe, was a good amount of work but not too bad, i only used 5-6 gallons not that heavy, this is why its relegated to cloning duty, besides ya cant grow too many plants, maybe 2 larges