Tank Lighting on 150gal

[Widdyhammer]

I have a 72" 150 gal tank that is currently being lit by 4 175 MH and 2 72' VHO 454s that I don't think are doing anything because they are mounted to the front of the hood not the top.

Would I be better off switching to two 400 MH and 2 175 MH and just take the VHO out?

I was previously running 3 175 MH but the center light was right on top of the center brace melting it away and 4 VHO (2 454 and 2 actinic).

I understand the difference on the heat generated by the 400s vs the 175s and would be buying a chiller to compensate for that. I have thought about 250 MH, but if I'm going to buy 2 more ballast, why not 400s.

[Ron Reefman]

As to whether or not you need to change lights. You say, "I don't think they are doing anything." What do you want them to do? They provide light mostly in a bluish spectrum. They do a different job than the MH. The more important question is what do you have, or plan to have, in the tank. Four 175w MH is more than enough for almost any corals. I assume your tank is about 2' deep? How close to the water are the MH? The 400w MH could be good if you have an all sps coral tank. But I seriously doubt you need them. You might just be wasting money.

[Widdyhammer]

the VHOs are currently mounted to the front of the hood in the vertical position, not horizontal, so the light is being directed in the wrong direction, plus the reflectors that are on the 175s are so large that they almost cover up the VHOs. I do want mostly SPS with a few LPS. Right now the 175s are about 10 inches off the water, but I would be building a new hood that would raise the lights to around 12 inches to better disperse the heat.

[Ron Reefman]

OK. Here are 2 things I would consider. 1) If you get the new lights, for a few more bucks you can get adjustable ballasts that can do 250-400w. If you want to reduce the amount of light, all you need is a new bulb. They are very nice ballasts. 2) If you are building a new canopy, make the light mounting flexible. Hang the lights so you can raise and lower them. Height isn't much of a big deal as far as cooling goes. A good fan can do a lot. But given you will have a lot of light, you can start with new bulbs raised up and lower them over time as the PAR falls off. Good MH bulbs can last up to 2 years or more doing this (althought to do it right you need access to a PAR meter).

[aecasasus]

OK. Here are 2 things I would consider. 1) If you get the new lights, for a few more bucks you can get adjustable ballasts that can do 250-400w. If you want to reduce the amount of light, all you need is a new bulb. They are very nice ballasts. 2) If you are building a new canopy, make the light mounting flexible. Hang the lights so you can raise and lower them. Height isn't much of a big deal as far as cooling goes. A good fan can do a lot. But given you will have a lot of light, you can start with new bulbs raised up and lower them over time as the PAR falls off. Good MH bulbs can last up to 2 years or more doing this (althought to do it right you need access to a PAR meter).

+1! PAR meeter needed indeed.

I run (3) 250w halides with 4 t5 actinics and the coral thrive. I get 3,000PAR's just under water level with lights at about 8" from surface. Ended up having to raise them another 4". Still, the lowest reading I get at sand bed is 250 (just to prove (3) 250w are more than enough). (2) 400w and (2)175w might be overkill!

Good Luck...

[Widdyhammer]

Having a center brace is a pain b/c i would have to offset the lights if I went down to three leaving the tank uneven. When I had the 3 175s I had a noticeable shadow down the middle of the tank. To get rid of that I purchased better reflectors and went to 4 175s and did away with the 4 72' VHO's. I agree on the adjustable ballast if I do purchase new ones.

I also want to build a new stand for the tank as the one I have it on right now has all the weight on 4 legs that sit on my floor. I want to change the design to one that distributes the weight of the tank across the entire floor it is sitting on, as well as, make it a little taller. Hopefully the new stand and hood will be a January project as my wife wants to set up a sea horse tank and I am setting up a QT and frag tank that I can move everything in the tank to for a day or so while I do the move.

I was hoping with 400s MH (2000K) being the inside 2 lights for SPS and have the outside 2 175s MH (1000K) for growth and LPS.

I have a controller that I would set to have VHO 454's come on for a wake up, then the 175's for sunrise, then the 400s for around 5 hours in the middle of the day.

My last order online was for 10 175 bulbs from various manufactures and different K to try to get a good color, but wasn't able to get anything other than white, so part of me wanting this lighting change is I have seen how much a difference 400s make with not just appearance but with coral growth.

Maybe with the adjustable ballast I could start with the 250s and take it from there.

I will use the 175 ballast that I take off the tank for my frag tank and the VHO ballast for lights over the sea horse tank so there is a plan to use them.
Thanks for all your post.