Tropical Fish Keeping - Aquarium fish care and resources

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-   -   watt per gallon rule (http://www.tropicalfishkeeping.com/saltwater-aquarium-equipment/watt-per-gallon-rule-4843/)

Mrmofo 04-08-2007 07:21 AM

watt per gallon rule
 
the unit for light intensity is the LUX, in my electrical course im doing u can get multimeters which are light sensitive.i think the watt per gallon rule should be abolished due to the efficeiencys of light fittings...a 400watt MH uses the same power as 4 100W light bulbs but gives off a higher efficiency where as a 40W fluro gives off about 300% of a 100 watt bulb, yet uses 40% of the wattage.which means to make up the same wattage u would need 10 40 watt fluros ot make up 1 400MH but the fluros would give off so much more light intensity.i believe it should be measured in LUX per gallon due to so many variables anyone else agree or see my point?this way u could compare the light given off by other fittings and reflectors/protectors and an actual measurment for light output other then how much power is consumed.sort of like a car can chew 20gallons of petrol compare to a car that can chew 10gallons but not have a distance to compare how far they get.i should copy right this idea if its any good hmm

herefishy 04-08-2007 10:50 PM

Oh my, a person who has taken up the ineffectiveness of the watts/gallon rule. My preaching has finally fallen on ears of reception and understanding. Lumens or LUX should be the determining factor when selecting lighting. Watts are just going to let you know how much the electric company is going to charge you each month. To figure the efficiency of your lighting divide lumens by the wattage. Lights not only have to have intensity, lumens or LUX, but the spectral curve should also be of the type that accommodates the need of the tanks inhabitants.
This is as much for those of us who keep saltwater critters as well as freshwater.

Mrmofo 04-09-2007 09:22 AM

hmmm well its a good idea and id luv to get really rich from making a device which measures the intensity and make it water proof n let it feed my bank account.just getting the point across to many ppl which have prolly been drilled since they started the hobby that the W/G RULE is definate...

Mrmofo 04-09-2007 09:39 AM

http://bigbro.biophys.cornell.edu/~t...ight_Meter.doc breifly read this and it looks like it would work, basicly using a light senstive resistor and measuring the output voltage i think from using continuety, gonna give it a go if i get the spare chance

caferacermike 04-09-2007 02:17 PM

It's a great post Mofo but it's not the first time I've said it on this forum. You all must take into account that the average tank owner does not have all this test equipment lying around. Keep in mind that a tank owner is already concerned about so many things they may not understand and then you throw LUX at them. hey you guys did not even mention PAR? So the average owner can relate to a somewhat simple idea of wpg since they understand home bulbs for their lamps. Get the average lay person to understand all about LUX and you are a better person then I am.

More to chew on. FLour bulbs cannot penetrate water for crap. Halide has the ability to reach into water. I am setting up a 400g 7'x3'x3' tank right now. I will be using 4x400w 12K MH and 4 72" VHO Uri super actinic tubes for color. Go ahead and get the average hobbyist to understand what I just said, and yet that isn't even complicated by lumens, LUX or PAR. I've heard it all as to what type of lighting I should get. I was told to buy 20 tubes of T5 lighting as the LUX will be super intense compared to 4 MH bulbs. Hey any of you ever priced out a generic T5 set up x 20? Oh gawd I could buy a lot of halide ballasts, bulbs, reflectors and sockets for that kind of money. So my pocketbook would take a hit for no reason at all. And after arguing online with the self proclaimed T5 King in front of an audience of about 200 people, I asked will the T5 penetrate the 36" of my tank. He sheepishly replied, no it will not. I won that round.

There are so many other possibilities and combinations, not to mention unique situations, that is is almost impossible to say that one system is better then another. Will some work in other set ups, of course they will. For example could you run 2x 150W halides over a 55g reef or 5 T5 bulbs of about 40w? Yes and both would work well. But time again has proven that the pulsing effect of halides has a life giving quality like that of the sun which produces healthy coral that is stimulated to grow faster.

We could debate this all day long.

Basically flouro style bulbs reach a depth of usuable intensity at 12", be it T12, T10, T8, T5, or PC.

Halides reach 12" at 70-150w, 18" at 175w, 24" at 250w and 36" at 400w.

So now that we've taken some of this into account it can greatly change your feelings towards Lumens, LUX and PAR in a controlled environment like a classroom and change everything in a particular case by case fish tank.

Now we can argue about what Kelvin ratings do to LUX or PAR ratings as well. Would you recommend a 6,500K bulb or a 20K bulb? And at what LUX?

What about measuring different types of ballasts? Just because a bulb is rated at X wattage does not mean the ballast is pushing that kind of power to the bulb itself. There are many types of ballast arrangements. Is a 400w magnetic ballast more efficient, or exactly the same, as a 400w electronic ballast? the electronic ballast is generally 30% more efficient. Say what? They are both rated for 400w right? So how can they be different? The magnetic ballast uses a lot of energy to convert the 120v of electricity into the usable form the light bulb can use. Ah settled then right? Nope. Mag ballasts have a tendency to overdrive bulbs thus making them brighter then electronic ballasts. So this means a mag ballast bulb burns brighter and has more LUX then the same bulb on an electronic ballast. Settled. Nope. The electronic ballast will cause the bulbs to burn more stable and give a longer usable life span saving money in the pocketbook both on bulbs and electrical savings. Settled then right? Nope. A reefer keeping stony corals might actually APPRECIATE the over driven bulbs and therefore the extra costs could translate into better growth and better color thereby justifying the added expense.

WPG is only a guide, not a rule.

If someone came to me and said " I have 40w of light over my 50g tank", I don't care what type of lighting it is, it is still to low for a coral supporting reef tank.

Mrmofo 04-10-2007 04:55 AM

yea i totally agree with u on that mike, the lux may not penetrate, im not saying fluros r better then anything by any arrangement just that the Watt per gallon rule is being out dated by technology being more efficient, if measured in lux u could preach a specific type of coral needs a certain amount of lux where by the owner could buy a MH if the requirments r high or if the requirments r low for the type of coral ,then they could buy accordingly.im just saying u could actually give coral more of a success chance if there was a measurment and requriment u could tie to a type of poly or mushroom,then people just buying somthing that looks pretty then killing it cause they thought there settup would support it...esp if the animal is worth alot...esp for anenomea type aswell.im building a prototype using a multimeter and a light dependant resistor to make my own specific unit.then hopefully rebuilt it small n water tite so it displays somthing and floats in water so u could actually put it in water, measure the unit to be made at the depth u require...


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