watts per gal

[kzickovich]

stupid question but when you figure out the watts per gallon for your lighting do you include the actinics. For example is a duel 150 watt MH + 2 54w t5 + 2 54w t5 actinics is it enough for a 90 gal tank.

 

[Michael]

is there such a thing as watts per gallon? ive only 2 watts per gallon in my tank and cant imagine it being any better, ive got approx 190 watts over a 92 gallon tank, i think yours sounds fine imo

 

[vyerous]

From what I understand its all about PAR readings (meter that measures the strength of light, in a nutshell) not necessarily watts per gallon, that was more of a generalization.

The setup you suggested is more than enough to run SPS IMO.

 

[der_wille_zur_macht]

Watts per gallon is a poor measure, for many reasons. Depending on the MH bulbs you choose for that fixture, you could double it's output, or cut it in half. At any rate, it'll be fine for most photosynthetic livestock, just keep the more demanding corals higher up and centered under the MH bulbs.

 

[thegrun]

...but in answer to your question, yes most people include the actinic bulbs in the equation...with 4 to 5 watts per gallon being the standard reef numbers. It's not all that accurate, but it gets you in the ballpark as to what to look for.

 

[davewbush]

Every thing I used to read in the past talked about watts per gal. When I got on reef central I found out that its not the way to do it, or not the sugested way. It was news to me too.

 

[dots]

<a href=showthread.php?s=&postid=14837640#post14837640 target=_blank>Originally posted</a> by davewbush
It was news to me too.

It was an older method of lighting estimation. One of the reasons this is such a great hobby is that we are always learning new things and adapting new information......as a result many "rules" are modified or discarded as needed.

Nothing is set in stone, but there is an amount of logic behind some of the "do's and don'ts" you might enounter. Most of the time it is to avoid future problems that can be devasting down the road, or otherwise set you on the path of success with the best odds.

 

[KarlBob]

One big reason why watts per gallon is not a good rule of thumb has to do with depth. A 12" Long x 12" Wide x 36" High tank and a 12" Long x 24" Wide x 18" High tank would have the same volume in gallons, but even with the same fixture, they would have very different amounts of light reaching the bottom of the tank. The farther light has to punch through water before it reaches your corals, the weaker it gets.

The construction quality of a light fixture can make a big difference, too. T5HO or MH lights with cheap reflectors will not penetrate as far as lights with good reflectors.