optimal canopy height for MH lighting

[yraveh]

I have a 120 G tank with PC lighting. I would like to change to MH (2 250W bulbs). I was told that the current canopy's height of 9 inches is too low for MH lamps. Is it so? what is the optimal height for MH?
in case I decide to build a new canopy, adiitional advices would be appreciated.

 

[reefnetworth]

the norm is about 8" for MH with fans drawing and pushing the heat from the canopy.

 

[corals b 4 bills]

I biult this one out of two sheets of plywood and some 1x3's for my 155 bow front tank with three 250 watt MH's, think i'm 10" off the water.

 

[mfinn]

On all my tanks I have the bulbs 9" off the water, and I use 2 pc fans to blow air in.

 

[yraveh]

Great. So I do not need to build a new canopy. Do I need to put a lens between the water surface and the bulbs?

 

[widmer]

9 " sounds pretty average to me. I bet the average range is 6 to 14 inches. IMO your top priority is to do whatever you can to get the most light out of that bulb into your tank without overheating the tank.

 

[Gold Stripe]

You have to consider that depending on how you mount your lights the bulbs will be a good 2in lower than the top of your canopy so then you are only looking at 6 to 7 in off the water. Very marginal. If there is any way to just add some trim or something and raise up your canopy 3 more inches it would be a good thing!

 

[Gold Stripe]

By the way, Corals B, VERY NICE WORK! The only thing that kept me from going bow front was the thought of having to engineer a canopy.

 

[mfinn]

<a href=showthread.php?s=&postid=12563743#post12563743 target=_blank>Originally posted</a> by yraveh
Great. So I do not need to build a new canopy. Do I need to put a lens between the water surface and the bulbs?

Only if you are using de bulbs.

 

[yraveh]

I will check that out!

What about the lens? do I need one or is it the marketing need of hamilton technology's sales rep?

is DIY going to be significantly cheaper than retrofit kit?

Any recommendation for a specific lamp manufacturer and seller?

 

[Slakker]

If you're using a double-ended bulb you will need a lens. The shield filters out harmful UV as I understand it, and also protects the bulb itself from splashes, etc.

Single Ended bulbs have the shield built right onto them, so you would not want to add another pane of glass between them and the water.

Edit: I forgot to say, I'm 10" off the water over my TWELVE gallon tank with 175w MH. It blows my mind that you guys with bigger tanks aren't substantially closer.

 

[corals b 4 bills]

How much closer do we need to be to get the light we want without burning our forearms every time we get in the tank? I'm upgrading to a 215 this year and I will have an in wall with a fish room, the lights will be on a retractible light bar with luminarcs so I can get the light even closer.

 

[chrismhaase]

Mine is about 17" above the water. The reason for this is I have the lights on chains that I can raise to get them out of the way while I am working or when I add new bulbs I can raise them so I can acclimate corals to the new lights and then also lower them as time goes on.

Here is what it looks like when it is closed

 

[hllywd]

This is my build thread. Not sure exactly without measuring how high I am off the water, but for reference the tank is 24" tall x 48" long. When it's hot my water goes to about 82F or so. I have one 4" AC fan blowing into the canopy. This works great for me with 2x250W MH and2x96W PCs.

http://www.reefcentral.com/forums/showthread.php?threadid=1163749

Tim

 

[hllywd]

Mine are about 8" just went and measured. That distance wasn't designed, simply where they ended up after I built the canopy to look pleasing to me. You'd need to keep a close eye on heat and evap rate with 250s in an 8" tall canopy. Mine is 10" tall from the top of the trim to get 8" from the water.

Tim

 

[yraveh]

hllywd,
Looks great!
Did U DIY the MH or did U buy a retrofit kit? What manufacturer and store?
R the PC bulbs actinic blue?

 

[chrismhaase]

I have a hard time reaching 80.5 in mine. I have (4) 4" fans to hel p circulate air and it is controlled by a AC Jr.

 

[hllywd]

Thanks yraveh,

I built it of parts that came with the used system I purchased. Both CoralVue ballasts that came with it went bad in the first few months and I replaced them with CoralVue's new style 250W ballasts. I also replaced the twin reflectors that came with it with a single 36" PFO. The twin 96W PCs are the actinic/10000K daylight combos with a dual SunPaq ballast. I have them on in the late morning for a couple hours until the MHs come on then again as the MHs are going off for the day. The MHs run for about 8hrs a day for a total photo period of approx. 12 hrs. I put 4 LEDs in the canopy powered by a Lunar Tracker for moon light and it all seems to work pretty nice together.

I got the ballasts from phishybusiness.com (actually from the physical store).

The reflector came from a place I can't remember the name of online. It took about 3 weeks for delivery and the guy didn't communicate very well... just do a search I found lots of places to order them after the fact.

The sockets are standard SE moguls, Serdar @ Phishy Business should have all the parts to get you going fairly reasonably.

If I can help any more let me know!

Tim

 

[yraveh]

thanks for the info. I will keep searching.
So far several consumer rep claimed that I can't go wrong with the IceCap electronic HQI ballast . I was recommended the XM 10K bulb (I plan to leave the current PC actinic bulbs in place).