[H-Dguy]

I thought I was ordering a 150w MH to hang from one end of a new 75gal discus tank, but I ordered a 400w MH by mistake. I was thinking maybe I could hang it over my 120gal which of course is deeper and move the t-5 lights off the 120gal to the 75gal.. My question is how high to hang the 400w system above the 120gal?
Thanks

 

[epicfish]

It won't cover your entire 120 gallon tank. I'm guessing it's at least 4-6 feet. MHs cover an effective area of 2'x2'.

 

[H-Dguy]

Yea,
You're right. I'll probably get a 2nd 75-175watt system since the aquarium is
5'. I'll hang the 400w at 24''to 28" and a 75w at 18'', then pump in the Co2.
Thanks again

 

[attack11]

It won't cover your entire 120 gallon tank. I'm guessing it's at least 4-6 feet. MHs cover an effective area of 2'x2'.

that's a myth. it depends entirely on the reflector you use. such as this fixture designed for 5' x 5' with 8' x 8' supplemental coverage.

http://www.plantlightinghydroponics.com/yieldmaster4-400w-metal-halide-ss10-remote-grow-light-p-1251.html

 

[epicfish]

Er, wouldn't that be a good fixture for aquatic plants also? For $183 + shipping, that's 400 watts of lighting! I was planning to do 2x150W MH, but that'd cost well over this $183!

 

[attack11]

it'd be perfect for freshwater aquatic plants. they require the same light frequencies as terrestrial plants.

 

[turbosaurus]

that's a myth. it depends entirely on the reflector you use. such as this fixture designed for 5' x 5' with 8' x 8' supplemental coverage.

http://www.plantlightinghydroponics.com/yieldmaster4-400w-metal-halide-ss10-remote-grow-light-p-1251.html

This is exactly what I have been looking for!
But what mounting height are they talking about? Different mounting heights would have an effect on coverage, right?. Lower would mean less spread, higher would mean less intensity...

And I would imagine that the way light travels through water is not the same as through air, so I wonder if the same thing applies to fish tanks?

Has anyone tried it?

 

[attack11]

i'd say avg height of 6-8' from the floor. lower will focus the light more, but i doubt you want that much heat right above your water.

 

[turbosaurus]

That would be 6 or 8 feet from the floor? Which would be about 3 feet above the tank? or 5 feet above the substrate? give or take based on ceiling height, tank height and stand height.... Figure the average room has 8' ceilings, average stand is probably 30"? and any tank big enough to consider a 400w mh would probably be 24 to 30" deep? That sound about right? or are you thinking 6-8' above the substrate?

I wonder how that would look? you'd light up the whole room. Or maybe not, if your reflectors did a good job of focusing it?

 

[dipan]

That would be 6 or 8 feet from the floor? Which would be about 3 feet above the tank? or 5 feet above the substrate? give or take based on ceiling height, tank height and stand height.... Figure the average room has 8' ceilings, average stand is probably 30"? and any tank big enough to consider a 400w mh would probably be 24 to 30" deep? That sound about right? or are you thinking 6-8' above the substrate?

I wonder how that would look? you'd light up the whole room. Or maybe not, if your reflectors did a good job of focusing it?

Depending on the setup, it could be a problem with a rectangular tank. The lighted area is listed as square. That would mean considerable light in front of and behind the tank.

 

[attack11]

every light will do that unless it's blocked. granted, this one will definitely put more on the floor because it's designed to

you can make it work, or you can go with other reflectors. there's a lot. usually 400w lamps are free floating and hidden.

 

[epicfish]

Advisable to put a $169 250W or $189 400W MH over my 40 gallon, 36" long tank?

 

[attack11]

depends what's in it

the 250w is probably a better choice unless you're stocking a bunch of sps corals.

 

[epicfish]

http://www.plantlightinghydroponics.com/sun-system-250w-metal-halide-enclosed-grow-light-p-1327.html

or

http://www.plantlightinghydroponics.com/sun-system-250w-metal-halide-enclosed-grow-light-p-1246.html

For a 40 gallon FW planted tank?

 

[attack11]

you need to decide on your own; but the one for $190 has a better shaped reflector. i don't know what kind of ballast they use, but based on the price i'd assume it's not electronic so there would be a hum. something to consider.

 

[epicfish]

Holy moly. I might just stick with my DIY setup using a Brinks hood or a Regent pendant. Works out to be ~$200 also, but I get 2x150W with two electronic ballasts.

 

[attack11]

i bet that'd be easier to work with in the long run. trust me, a ton of par without enough plant mass is just a pita.