Reflectors mount length or perpendicular?

[scubadude]

Well the Subject says it all. Im building my own canopy and Im wondering which would give better spread. The tank is 72"x24"x30" (220gal) and Im looking at one of the 2 lighting options.

Option 1

2 - 250HQI double ended Ushio 10k
1 - 175MH Ushio 10k

Option 2

3 - 250HQI double ended Ushio 10k

I dont know if I want one long reflector (length of the canopy) or 3 seperate reflectors mounted perpendicular. your opinions and suggestions would be appreciated.

[Ninong]

Scubadude,

Usually the decision on whether to mount perpendicular or parallel is based on the design of the reflector. Often, folks who have a tank that is 30" front-to-back will choose a parallel reflector and those whose tank is only 24" front-to-back might choose perpendicular reflectors. It appears that your tank is 24" front-to-back.

However, everything depends on the type of lamps you are going to use and the type of supplemental actinic lighting, if any.

Looking at your options 1 and 2, it appears that you are not planning any supplemental actinic lighting, right?

Most people mount the double-ended HQI lamps parallel to the front of the tank. All of the German lighting fixture manufacturers mount double-ended HQI lamps parallel, even if the fixture contains only a single lamp. (I believe the little PFO mini-hoods may be designed to be mounted perpendicular.)

One question for you: in option 1 you show two HQI double-ended lamps and one mogul base lamp--is this because you already have the 175w Ushio 10,000K mogul base lamp? Just wondering why you would want to mix the two different styles. According to Sanjay's testing, the 250w Ushio 10,000K HQI double-ended lamp puts out a little more than double the PAR of the 175w Ushio 10,000K mogul base lamp. Also, they are normally mounted in different style reflectors.

Here is a killer idea, but probably on the expensive side: use three 250w Ushio 10,000K HQI double-ended lamps plus two 150w 20,000K HQI double-ended lamps (250-150-250-150-250). Run the 20,000K's as "actinic" supplementation and as dawn/dusk effect.

Regards,

Ninong


Facta, non verba. Fiat justitia.

[golfish]

I would go with option 3 and use 3x400 watt 20K bulbs.....Your going to have to raise the HQI's up pretty high to cover that size tank. I know I use them on my 150 and they don't come close to covering a tank like I have, 48" long x 24" tall x 30" wide. I also use a 400 watt Iwasaki on my 150 along with the two 250 watt HQI's.......

If you don't have the lights yet you might want to consider the 400 watt 20K's ran on an HQI ballast........IMO, you'll need more then three 250 watters.....