metal halide lighting times??????????

heys guys i'm confused
i have a 5x2x2 with 3 150w metal halides now i was told to keep my halides on for 12 hours a day. i just read in a different thread that i should only have them on for 8 hours. which 1 is it i'm totally confused

now for a different question (they are probably both related) i have some wicked algae ,green slimy stuff growing on my sand. its thick i can stir up the sand and the algae sticks togethor like clay aslo i can clean it 1 day and its back the next

i'm new to all this stuff so if there's something i need to buy so be it

any info would be great
dave

 

It all depends on the tank really and how much u want them on. There is not a right or wrong answer here. I run my for only 5 hours a day and have seen a huge increase in growth.

 

+1. I know people who only run their MH for 4 hours a day, but the actinics for 12. Personally, I go with 10 actinics and 7 MH. Cutting back the MH could help you with the algae growth and its a good possibility that these 2 issued are related.

 

I keep my Actinics on for 10 hours and my MHL on for 7. All corals do great under this and I have no algae growth at all.

 

The lighting wont be helping your algae issue, but its not the only contributor
nutrients also need to be controlled - do you measure Nitrate and Phosphate
as excess levels of those nutrients combined with excessive light does often equal an algae menace

Steve

 

Generally people run the actinic lights to simulate dawn to dusk. I run mine 10 to 10. Main lights as said above is up to you and your tank. I run mine about 5 hours in the summer here lately I've been running 7. Going down in the light cycle won't hurt anything but if you increase I would do it in 1/2 hour increments.. For instance I wouldn't go from 5 hours to 8 in one day. The corals need to adjust.
Do you have actinic lights? Some people do run 12 hours because they don't have actincs.. .seem like it would create a lot of heat and wear out the bulbs though.