tangs don't belong in small tanks. a 40 is a small tank IMO
/IME. i'm not saying i haven't kept them in such, but i'm saying i don't recommend it for long. if you are expecting to upgrade in a short while, then it's ok, but if the 40 is the largest you will go, i say -pass on tangs.
wattage isn't what you shoot for with lighting. you need to figure out what corals you want to keep, then figure out what type of lighting you will use. if you go with metal halide, you would have to go with 2 x 150 or 250. i would go with 250 watters because your tank is 22 inches tall. i used a bunch of coralife clip on 150 watt halides over an 8' tank that was only 17" tall, and browned out a lot of sps
because of lack of PAR. PAR= photosynthetically active radiation. this is the usable
light that is over our tanks.
Jebo is a low end company from jump, so i am betting the light they sold you is compact florescent or t-5s with a single reflector.
if i am correct, this is suitable for only low light corals.
you will need (to keep anything and everything) metal halide, or T-5 H.O. that is individually reflected. (a single reflector for each bulb)