MH Light Height

[cbong]

I remember seeing a thread on how high to hang the MH light, but couldn't find it with search. It shows a diagram on spread of light, with calculations of how to position the lights.

Found threads suggesting 20-30cm above water level. Any suggestions for a 4 x 2 x 2 feet tank? Thanks

[Goondoo]

I remember seeing a thread on how high to hang the MH light, but couldn't find it with search. It shows a diagram on spread of light, with calculations of how to position the lights.

Found threads suggesting 20-30cm above water level. Any suggestions for a 4 x 2 x 2 feet tank? Thanks

I am using a pair about 30cm above "sea" level

[Livaio]

It should hang 6" above the water level to be exact!!

[Goondoo]

It should hang 6" above the water level to be exact!!

Don't ever try it unless you running chiller

[Livaio]

2x Fans and chiller is used for the 6" way

[budak]

With MH, I think you will have to tinker with the height as you go along....if algae develops, all things being equal, you could try raising the light level and/or reducing the lighting hours (for my own tank, my 150W light is 25 cm above the water (+ 2 AC fans) and anything above 8-9 hours triggers algae). Observe on a weekly basis and adjust accordingly.

[Rupert]

On my tank I have my Dymax Hi-lux MH’s [300 watts] & FL [60 watts] six inches above the water, but a chillier is definitely needed as the intensity/heat of the emitted light is impressive. The MH’s are on 6.5 hours.

Tank - 122cm (L) x 61cm (W) x 76cm (H) or in inches 48 x 24 x 30

[Livaio]

Ya.. All depends on the condition of the plants and the water.

[augi_ow]

i've read at dennerle website saying a break in between lighting periods will prevent algae...
my 150W MH is about 25cm above water level..running chiller at 26 degrees cause mine is a moss tank...
the lights are on from 7-11 in the morning and 7-11 at night...
the website on dennerle say 4 hours is a good length for plants to photosynthesis and they too mention that algae dislike "light breaks"
just quoting from dennerle website and trying out on my 3 feet tank now... =) will let ya guys know about the results..

[gchoo]

depends on the type of plants. for plants that require high light, have to put it closer 6". you will have to raise it higher for the other plant types or risk burning them or turning them into emmersed form

[theodore]

cbong,

I run my 2x 150W MH ~30cm above water surface for 6hrs a day. It's the nearest I can go before temperature hits 29deg C since I do not have the luxury of a chiller.