is 2-175 watt mh enuf for a 72 bow  or should i up grade to 250 mh i see my red cap is browing out and dont know why

175's would be marginal to maintain color towards the middle to bottom of the tank. I have used them on tanks at 18", but was much happier with the 250w lights when I went to them, both in terms of growth and color.

Billy

thanks very much for info

sell those 175s and get 2 400s, I wish i had 400s rather than 250s

If the bulbs are fresh, lights are close to the surface, and the coral is in the top half of the tank I would look at your water parameters before blaming the lights. Red cap is not a hard coral to keep colored up with medium light and quality water. I would look at phosphate, alk, and even nitrate levels.

Yep..... almost always browning of corals is caused by water parameters like access nutrients or hi PO4.
Unstable parameters can also attribute to browning of corals.

eins