i have a 120 gallon tank,a 65 gal. sump,a lifeguard quiet one pump(type up15-42..flo rate unknown),and a hang on return yellowed and cracked(flo rate unknown).this setup was running through uv light approximately 3 ft. then 6 ft. to main tank.the pump is pretty much burned out(which is where i learned about head pressure etc.. and research).at this point i figure i need a pump of atleast 1200gph. or moreso if im on base i would have to match the return for 1200 gph.so,..would i have the tank drilled for a return(or returns) or should i get an overflow to match the pump?

DRILLED DRILLED DRILLED DRILLED DRILLED DRILLED. Trust me its a LOT let hasle. no worries with a drilled tank. no back flow. no overflows....no loss of siphon. certainly want a drilled tank.

yea fishboy is right...get a drilled tank, i took down my big tank due to hating maintinance with a siphon overflow. i will never set up a big tank again unless its drilled.