Metal Halide Lighting Time

[AaronS]

Good afternoon all, to preface, I am doing some adjustments to my well established tank. I have had this tank going for around 14 years at this point, back in the day I used to be very involved with the tank, reefing, fragging, etc.
These days its mostly maintenance and hands off.
I have always had trouble growing coraline in the tank, it usually looks white on the glass, purple in the corners. The corals themselves do well.

I have 3 250w 20,000K Radium MH bulbs above the tank, and 2 ATI T5 bulbs (4 feet length, not sure of the wattage atm), the tank is 6‘ long 125 gallons.
What sort of lighting time for an average mixed reef, would you all run the MH and the T5’s for?
Currently the MH are on for six hours, I have backed them down from 8 hours a day.
The T5 are on an Hour before and an hour after the MH, with 30min or so overlap.

 

[90gDreams]

I'm running 10 on the halides for my 90g, 1hr either side with 2 4' ATI bulbs. Could definitely get away with less but I just like to have light on the tank as much as possible. 250w Phoenix 14k

 

[civics14]

I can't speak for halides, but for my peak setting I run them for 6 hours. 2 hours up and 2 hours down, for a total of 10 hours of light. It seems to work for me, every tank is different.

 

[enderg60]

I ran a similar setup to you. Started as 3x400w radiums with 4x 36" 50/50 T5s and 4x 36" actinics. I swapped the T5's for a DIY LED setup.

10-11 : blue LED
11-12 : all LED
12-8: Halides and LEDS
9-10: all LED
10-11: blue LED

If you have the means to control any algae growth and heat run them as long as you want. I wouldnt go under 5 hours a day on the main lights personally though.

Lights on longer just means more time to grow so youll need increased flow and dosing over fewer light hours.

 

[AaronS]

Thank you all, I will start upping the light time and probably land it around 8HR of MH a day. I just changed the bulbs so for the moment, I want to keep them a little shorter.

 

[reefkeeper]

Back when I had my 330 mixed reef. I had 5 Lumibrights Reflectors running 250watt radium's and diy blue Led's for color pop. I ran the MH's for 8 hours a day while running the blue Led's at the same time. During the summer the MH's would generate a numerous amount of heat in the canopy I had fans on the Apex that triggered on/off at certain temps. I also ran a chiller as well. My SPS and coral growth was awesome. I did have to replace the Radium's every 7-8 months.