Required Watts per Gallon

[AndyH5512]

Hello everyone. I am about to take the plunge and buy some MH lighting this week. I would like to know what everyone has to say about the required watts per gallon on a reef tank that will include clams. My tank is 120 gallons. Also, when figuring the WPG, I include all lights that are in the lighting system, correct? For example, I add the actinics that accompany the MH, right? I have been looking at the Current USA model at the LFS. Thanks.

 

[Snoopybdb]

i have 6 wpg in my 30 gal tank. I have a clam and it is doing VERY well. I've had to move it because it got to big for when i had it in the tank. http://www.marineandreef.com/shoppro/power_satellite.html
This is the brand i have. I have the 36" dual light (2x96w)

 

[Snoopybdb]

i have 6 wpg in my 30 gal tank. I have a clam and it is doing VERY well. I've had to move it because it got to big for when i had it in the tank. http://www.marineandreef.com/shoppro/power_satellite.html
This is the brand i have. I have the 36" dual light (2x96w)

 

[DragonForce]

If you're going to spend the money on MH I would get atleast 4 wpg. I have 2 clams in my 37 and have about 4.7 wpg.

 

[DragonForce]

If you're going to spend the money on MH I would get atleast 4 wpg. I have 2 clams in my 37 and have about 4.7 wpg.

 

[greenmaji]

how deep is your tank?
Im assumign its 4 foot long and under 24 inches.. if so.. 2-250 watt MH bulbs is what your going to be looking for..

the wpg rules dont appy with MH.. the wpg numbers are much greater on smaller tanks then the same amount of light in a larger tank..

MH is more about the depth of the tank and the coverage.. 2 foot per bulb..
depth and watts.. for high light critters..
175 watts for 18 inches or less
250 watts for 18-24
400 watts for 24+

diffent bulb and ballast combinations will give you more PAR or usefull light then others.. soo.. for example if your looking at somthing closer to 24 inches deep a good 250 watt setup would be better then a not so good 400 watt setup.. HTH

 

[garth7]

MH lighting

I have to agree with greenmaji here. I believe that wpg is a good rating but from what I have read in my endless search of knowledge is that the dept of the tank may matter more.

I would say watts per gallon is a good rule of thumb when going with a typical tanks setup. But the real factor should be the light getting to the bottom of the tank. The deeper the tank the less the amount of light will be at the bottom of the tank.

I did read once in a book that there is some long drawn out way to calculate the amount of light needed. I think it was developed by some rocket scientist at NASA (it would take one to figure it out). If I can find this at home I wll post it.

But as always, these are my opinions and I could be wrong. I am in the process of upgrading to MH as well and have used VHO for 3 years. I need to learn that if it aint broke dont fix it.

Happy reefing.

 

[AndyH5512]

It is 24" deep. Both of my reputable LFS's say that the Current USA MH unit will do the job. I just wanted everone here to chime in with experience, comments, etc. I am really looking forward to adding some nice pieces of coral in the near future.

 

[macman7010]

the depth of the tank is the main thing to consider when looking at wpg. Naturally deeper tanks need more wpg and more wattage. For any system that is keeping clams, 6 wpg or more is needed in my opionion.

 

[greenmaji]

If your going with 250W MH I would recomend PFO electronic HQI ballasts and some 6500K bulbs.. with some 03 suplement for color.. that would be the only ballast and one of the only bulbs up to PAR, pun intended, for the job..

If you go with 400's your current USA would work fine..

you'll find LFS advice to not exactly be in your best intrest.. do they expect you to be buying your livestock from them? if so.. they have a vested intrest in your failure.. we on the other hand have nothing to gain from giving you our advice but a consern for your success so youll stick around and post up this board instead of getting frustrated and quiting the hobby.. just something to think about..

 

[garth7]

Green is right. I love the old man at my lfs, but lets face it, he is the only one in town. If I sucseed, then I dont come back quite as often. If I fail, I am in there more regularly. This is why I got addicted to these posts. It is the best way to learn. Books are good but this is personal and great! I have a 55 gal and am looking to get 2 175W MH. Then supplement with some actins. If you go by the watts per gal rule then its over 6. But then I found that you have to watch the kelvin ratings on the bulbs for color and color growth.