quoting:

Lumens=1200 on first 2 lights I bought and they were really dim.
LOWES,HOME DEPOT I couldn't find one higher than 1250 Lumens?

[...]

You may just have a cheap undersized ballast that underpowers the
tube. Ballasts are universal as well and the bigger the tube, the
more underpowering. Usually the 20W tube is the biggest tube that
size ballast can operate. Though in most good ballasts tube
brightness is faily high across all tube sizes.