MH Bulbs - Retrofit installation

[steve149c]

Hi all,

I'm really struggling with my Watts/Litre. My tank is a 270L Bow fronted, which means that the rectangle section at the back is 120cm x 26cm, and then the front bows out 19 cm more. I can't buy an off the shelf lighting system.

If I install regular T5 tubes I can only get 3 x 34" tubes, producing a total of 117 Watts, which is about 0.5 Watt/Litre.

Therefore I have looked at mounting two 150W Metal Halides in the rear section, and a single T5 or possibly another 150W MH in the front section which would give 2 Watt/Litre. My questions are:

(1) What's the spread on the light, ie the footprint of the beam?
(2) How hot do 150W's get?
(3) How much gap above and below the lights do I need?

I may well resort to building a new lid for the tank, but before I do I'd be interested in the answers.

My tank will be Fish & reef, with soft coral/polyps to begin, but I might move onto hard corals later.

Any advice greatly appreciated,

Thanks

Steve

[cmor1701d]

I believe that a MH bulb sitting 6" -12" (15cm - 30 cm) above the water line should have about a 2' x 2' (60cm x 60cm) beam to the bottom of the tank.

I would think that you could get a 4 or 6 bulb fixture to go over the rectangualr part of the tank, but I have not researched that.

[Ziggy953]

I have dual 175w MH 2x110w VHOs and 2x54w T5s over the same tank. The rectangle part of the tank is equal to that of a standard 55g tank.

[steve149c]

Thanks for all that,

I think I am going to probably a 6 or 7 T5 system over the tank, mixture of lights for specific temp colours etc. Then I have some good control for the photoperiod of sunrise and set, plus lamps for a moon lamp.

So that should be 6x39Watt day lights, and 1x39Watt night light, giving me 234 Watts at day, or just shy of my 1 watt per litre aim (270L tank).

Thanks again,

Piccies on the way as I progress,

Steve

[Ziggy953]

Originally Posted by steve149c

Thanks for all that,

I think I am going to probably a 6 or 7 T5 system over the tank, mixture of lights for specific temp colours etc. Then I have some good control for the photoperiod of sunrise and set, plus lamps for a moon lamp.

So that should be 6x39Watt day lights, and 1x39Watt night light, giving me 234 Watts at day, or just shy of my 1 watt per litre aim (270L tank).

Thanks again,

Piccies on the way as I progress,

Steve

Just curious, why go with the 39w (36" bulb?) rather then the 54w 48" bulb? I used the 48" bulbs (54watts) on my 72 and could easily have gotten 4-6 over it. Just curious as to your choice there.