Please tell me if I'm heading in the wrong direction....

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maporsche

Aquarium Advice Regular
Joined
Aug 13, 2005
Messages
70
Location
Phoenix
with this MH light box:

The box is 16.5in wide x 22in long x 10in deep. I will have 2 of these in my canopy (which I've yet to begin building). The lights are 400w each and lighting my 120 gal.

The questions I have are:

1) These lights will be approx 10in from the water, do they need to have a piece of glass over the top of the box? The reason I ask is because the light get's quite hot and I assume the glass would as well.

2) Would it be good design to include a vent or fan on the opposite side of the box.

3) Am I missing anything?

Thanks guys.

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Since it is the single ended bulb, you should not need a glass shield unless you think there is a chance of water splash on the bulb. With 400w MH you definitely need at least one and probably two fans per box and even that may not be enough. Do you have a chiller? If not you may need to look into one to absorb that much heat.
 
Why are you using 400watt instead of 250? You would be able to keep anything under two 250's. How long is your tank? A MH will only cover a 2ft area "good"
 
MadManMac said:
Since it is the single ended bulb, you should not need a glass shield unless you think there is a chance of water splash on the bulb. With 400w MH you definitely need at least one and probably two fans per box and even that may not be enough. Do you have a chiller? If not you may need to look into one to absorb that much heat.

Do you think it will be that hot? The canopy will have at least 2 fans out the top of the canopy and an open back. I was hoping that heat wouldn't be a problem.
 
Brenden said:
Why are you using 400watt instead of 250? You would be able to keep anything under two 250's. How long is your tank? A MH will only cover a 2ft area "good"

I found a good deal on 400watt kit on ebay. I also plan on setting these lights pretty far above the tank, I'm thinking even higher now to help with the heating issue. My tank is 5 feet long. I have a plastic cross-member down the middle of my tank so 3 lights wouldn't work. I also thought that since I was only going with 2 lights that the higher wattage would help compensate for only having 2 bulbs instead of 3.
 
more watts really shouldnt give you more "spread" of light.. your still going to only have 2 good feet of coverage.. I would suggest planning it out that way (one foot of space total somewere isnt going to be getting enough light so put low light critters there if you get my drift)
personaly currious to see if you can get this to work.. it sounds kinda risky to have overpowered MH but what do I know :?
 
greenmaji said:
. it sounds kinda risky to have overpowered MH but what do I know :?

I must have missed something. From where do we know it is going to be overpowered? I agree that more watts will not increase coverage. The other thing to note is that if you plan on raising the height of the bulbs, you will get a nasty glare in the room. Heat most definitely will be an issue. You will not want to have any glass on the tank that will trap the heat in for sure. You may even need fans for the water. Or a chiller.
 
Just a idea but how about 250w sun replicator pendants? You will not have the big heat issues that come with 400w MH and they put out considerably more light than a 250w retro. I went from 250w retros to these and I can see a big difference. I found a good deal on them. If you want price info I found PM me.
 
So it would seem you guys are saying to step down to a 250w kit. Meaning that I would need to buy new lights and ballasts right?
 
400w lights are just not going to acclomplish what you think they are. You will still not have any better coverage than you would with 2 -250 watt lights. You will have a lot more heat and power usage. I thought I wanted 400w lights due to my tank depth. Everyone I talked to told me to go with 250w due to heat and coral bleaching.
 
I have taken a picture of my tank with one of the light boxes on. I only have one done so I can only test it with one. (see picture below). You can see that it covers at least half the tank (the blocks holding it up are blocking some of the light).

I picked these lights/reflectors/ballests up for $90 each, so it was quite a bit cheaper than any other MH option I've seen.

I'm not sure what coral bleaching is, so please elaborate on that. Otherwise, for the cost, I need to figure out a way to make these lights work.

Brenden, I appreciate the PM, but that's a very expensive option that I just cannot afford right now.

These lights are also about 9in closer to the water line than they will be in my canopy.

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No problem. I have 6 of the sun replicator pendants on my tank and I am very happy. If you have already purchased the lights then it only makes sense to make them work.
Coral beaching is the same as something faded in the sun. The 400w MH are very intense and corals will fade unless they are placed far enough away from the light. Since your tank is not tall this may be something you want to look at.
If it were me I would cover the inside of the wood box with aluminum flashing. Is is very cheap at lowes or HD. I am not comfortable with high heat items next to wood. I would cut a hole on the end of the box and put a 4" "computer" fan to keep the bulb cool. I would also look into purchasing some small fans to blow on the water. I bought two 10" personal fans at lowes cheap. It is doable you just need to make sure you have enough cooling in place.
Why are you using a box instead of just putting the lights in the canopy? Seems like they will just hold heat. I had retros at one time. I put a spacer between the reflector and just screwed them to wood. That way there was a air space between it.
 
Brenden said:
No problem. I have 6 of the sun replicator pendants on my tank and I am very happy. If you have already purchased the lights then it only makes sense to make them work.
Coral beaching is the same as something faded in the sun. The 400w MH are very intense and corals will fade unless they are placed far enough away from the light. Since your tank is not tall this may be something you want to look at.
If it were me I would cover the inside of the wood box with aluminum flashing. Is is very cheap at lowes or HD. I am not comfortable with high heat items next to wood. I would cut a hole on the end of the box and put a 4" "computer" fan to keep the bulb cool. I would also look into purchasing some small fans to blow on the water. I bought two 10" personal fans at lowes cheap. It is doable you just need to make sure you have enough cooling in place.
Why are you using a box instead of just putting the lights in the canopy? Seems like they will just hold heat. I had retros at one time. I put a spacer between the reflector and just screwed them to wood. That way there was a air space between it.

I appreciate your insights into cooling. I only put the lights in a box because that is how I've seen them be sold (usually it's a metal box though. If I don't need the box and you're saying I can place them directly in my canopy then I will defiantly go that route.
 
Sounds like a plan. (y) Would be easier to cool that way. Put a spacer between the reflector and the canopy. If nothing more than a couple washers on the screws you use to mount them.
 
Brenden said:
Sounds like a plan. (y) Would be easier to cool that way. Put a spacer between the reflector and the canopy. If nothing more than a couple washers on the screws you use to mount them.

I'm sort of glad that I don't need the box now. When I was building it, I was thinking to myself how nice it'd be to have a box like this to hold misc pieces of wood. Now I have one.
 
I've been testing the one light I have the last few days to determine what I can expect in temp increase. My 120 gal is heating up approx 4 degrees over the 9 hours I've had the light on. This increase is happening without any fans blowing on the tank or expelling hot air from the box. The light itself is also about 6in closer to the water line than it will be when my canopy is completed.

The bulb for my second retro kit is in the mail so soon I'll be able to test it with two lights.

The canopy will be completed and ready to be painted by the end of this weekend hopefully, and then ready for the tank by about the 22nd I hope.
 
You don't need to run your MH for any longer than 6 hours a day. Keep in mind that the summer months are going to be harder on the heat retention than the winter months (try running your heat at 76 while the MH are on).

Raising the 400w MH up higher over the tank is definitely going to help with the light spread and keep the dark areas under control. By adding a PC/VHO fixture into the canopy you can mask the effects. The canopy should help contain any overspray of the light.

You'll probably want to start your corals low in your system and move them up over the course of weeks as they become acclimated to the stronger lights (new ones as well unless they were kept high under 400s originally). Some LPS and Monti species will want to stay on the bottom as they don't really like a lot of light to begin with.

Coralvu makes a ReeFlux bulb for the 400w MH in a 10K that is supposed to be out of this world for color and growth. I run 250s over my 120, but know others who've run 400s over a 30" tank with no ill effects.
 
Hara said:
greenmaji said:
. it sounds kinda risky to have overpowered MH but what do I know :?

I must have missed something. From where do we know it is going to be overpowered? I agree that more watts will not increase coverage. The other thing to note is that if you plan on raising the height of the bulbs, you will get a nasty glare in the room. Heat most definitely will be an issue. You will not want to have any glass on the tank that will trap the heat in for sure. You may even need fans for the water. Or a chiller.

Maybe I was assuming too much.. isnt a 120 gallon only like 24 inches deep?

you would need to use sheilding to prevent the uber glare and it might not be attractive..

side note: the mention of the ciller made me think of this.. Ive had an idea for a DIY chiller as of late (though I really dont think I would need one exactly I just figured out a really good way to do it.. :p )
 
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