how much light does a PBTA need?

[dinesh_jay]

I have a PBTA in my 50 gallon tank which is 20" deep. I have a 250W MH 14K. How long do I need to run the lights? 5hrs, 10hrs...Thanks.

 

[ocellaris123]

I have a 12 hour photo period for my 150 watt mh. I would say anywhere from 8-12 hours would be fine.