I had a sump on my 50g for almost 2 years, while useful for hiding all the equipment and constant water levels, it gasses CO2 like no other.
My tank had a beautiful 36" x 18" HC carpet until I installed the cpr overflow, I did everything I could to keep CO2 from gassing off, installed valves, straight hoses, straight pipes, sealed the sump, etc... In the end my HC carpet was destroyed and BBA was out of control, wasted so much money on the damn thing. I realized the noise, dirty uncleanable overflows, and CO2 refills just wasn't worth the constant water levels and surface skimming.
So I replaced it with a good 2nd canister, $35 eheim surface skim 350, and a $40 water top off peristaltic pump
My carpet is begining to grow again.