MH for 5 ft.

[cbong]

I am thinking of having a forth planted tank.
A 5x2x2 footer.

Wonder if it is more economical to use MH lamps instead. Would 2 such lamps be enough? if so, what wattage per bulb?
Where can I buy them at good price?

Alternatively, what can I use?
I am currently having 6 x 36W PL for my 4 feet tank. Already looks crowded ... can't imagine the number for a 5 ft tank.
Any DIY design available?

[vinz]

For PLs, I would put 6 x 55W in three rows.

For MH, 2 or 3. I think 2 should be enough spread.

[plantmania]

I think MH is a better option for 4 ft & above.... Running cost is cheaper as the bulb last 2+ years and less prone to breakdown and intensity lost. Initially cost is higher but in the long run, MH is cheaper. Also the penetrating power of MH enables the light to have much strong light intensity for deeper tank( e.g 2 ft and deeper)

5ft, like yours, is around 110 to 150 gal depending on the depth of water. This equates to 330 Watts to 450 Watts for 3 Watts / gallon rule, So I would recommend using 2 sets of MH lights each 150 Watts. MH comes in 150 ,175,250 and 400 W....

Pricewise I don't really know where's the best. You can try lighting shops and ask for quotation. 2 sets of hanging MH , 150 Watts each , colour temp 6500K. Should only cost about 500 bucks, much more for those aquarium type MH though ( multiply cost by five times).

I agree 6 x 55 W is freaking clutter.....and 55W PL lights are more expensive than the 36Ws too. Imagine the amount of wiring too....

[cbong]

Thanks so much guys. I used the AQ Calculator and it says 448 W/USG. Wouldn't 2 x 150W MH be too low?

I suppose the volume is full volume and does not consider water-level and gravel depth??

[cbong]

[quote:876399def9="plantmania"]2 sets of hanging MH , 150 Watts each , colour temp 6500K. Should only cost about 500 bucks, much more for those aquarium type MH though ( multiply cost by five times)..[/quote:876399def9]

Besides the looks, why is the price difference so high??? Would I lose out on quality? E.g.

MTD150D 6,500K Ra96
150W Rx7s
SGD45.00

MT250DL 6,500K Ra90
250W E40
SGD95.00

The above cost of bulbs are from http://www.viclite.com/viclite/Eye20k.htm

[loupgarou]

2 x 150W MH bulbs at 6500K - 7000K will do for a 5ft.
thats what I'm using myself.

Anything more is going to be overkill

--

the 3 watt per gallon rule only applies to PL/FL lights.

NOT TO MH lighting.

a 150W MH bulb is much much brighter than 150W of incadescent and possibly 150W of FL as well.

[vinz]

The 3WPG guideline is not very relevant for larger tanks. Large tanks can make do with 2 to 2.5 WPG for light demanding plants. My own guideline for a 2 feet deep tank is 3 rows of PLs.

And like loupgarou said... it does not apply to MH. 150W of MH and cut through 2 feet of water and deeper. You just need one over each approximate 2'x2' area or slightly wider. 2 for a 5 ft should be enough.

What I don't like about MH, for you to consder and decide for yourself.
- Can't lower the light output. With PLs I can remove bulbs. (Unless dimmers work on the MH... I'll have to look into that. Maybe someone can answer.)
- Has to be high above the water to reduce heat, which means either hanging from the ceiling, or very high stands. I'm not keen about wires or trunking running on my walls and ceilings.

[cbong]

Guys,

how high should the MH be above the water level??? Pls advice, thanks.

one more thing, are MH lights attached to a 3-pin power-points???