How much light is too much?

[gozetec02]

Will 220 Watts be too much for a 20 gallon long. People here are always talking about the more light the better but how much is too much. This would be 11 Watts of light per gallon.

Will this aid in keeping high light corals and anemones?
Will this make my aquarium grow algea like crazy?
Also is it ok to use 2 24" fixtures on a 30" long tank and stagger the lights to cover the entire top?

 

[scuba_steve]

heat will be an issue ! but after seeing the japanese tanks running 7 mh dont see a issue other than heat ! mabe keep the light a bit above the tank !

 

[lando]

Maybe that is the key to those awesome SPS tanks! Must have an auto-top-off running.

 

[scuba_steve]

lolol shoot just run your ro unit right to the tank lolol

 

[gozetec02]

The recomendation for my 20 gal long since it is only 12" deep is 65 watts. Naturally a tank that is 24" deep will require tons more light then a 12" deep tank. So if a 20 Gallon tall tank is 16" deep and mine 12" deep. Wouln't less light be required to reach the bottom of the tank. And being closer to the light wouln't the intensity be higher.

Take a look at this site and see what i am talking about.
http://www.marineandreef.com/Info/infolighting.html
http://www.marineandreef.com/Info/lightingchart_hood.html

 

[scuba_steve]

http://reefcentral.com/forums/showthread.php?s=&threadid=317782&perpage=25&pagenumber=1

check out this link and tell me that charts right well let me at least say look at all the light and the wonderful coral

 

[gozetec02]

But those tanks are very deep they would need lots of light to reach all the way to the bottom at optimum intensity. If a 24" deep tank needs 130 watts for opitimum intensity wouln't a tank half the depth require half the light?

Take a look at this http://hyperphysics.phy-astr.gsu.edu/hbase/vision/isql.html#c1

 

[scuba_steve]

yea the light will have to travel less true ! and if ya go the 220 watt and keep the tank cool and water quality great ya will have a miniature tank like those

 

[loganj]

But those tanks are very deep they would need lots of light to reach all the way to the bottom at optimum intensity. If a 24" deep tank needs 130 watts for opitimum intensity wouln't a tank half the depth require half the light?

Take a look at this http://hyperphysics.phy-astr.gsu.edu/hbase/vision/isql.html#c1

I'd have to disagree with the statement that a 24" deep tank needs 130 watts for optimum intensity. The depth of the tank is a major factor, but watts of light aren't the best measurement. Several members here have 55 gal tanks with 2x250w MH systems and are reporting excellent results. You will not put enough artificial light on a tank to approximate the natural sunlight that the reefs get. 400w MH systems are not uncommon on 24" deep tanks. I know of one tank, 32" deep, that uses four 400w MH's and three 1000w MH's. Since we're talking about 20g tanks though, I had a coral prop tank with 190w of PC over it. It did require a fan to keep the water temp down, but coral growth was excellent. Anyway, lighting is a controversial subject and it really depends on what kind of lighting you have. 250w of MH is not equal to 250w of PC or VHO. The MH is much more intense because it is concentrated over a smaller area. In the end, it depends on what you want to keep in the tank. If you're just going to have soft corals, you don't need MH. If you intend to have SPS, although you can keep them under fluorescent lighting, MH tends to be much better.

 

[loganj]

But those tanks are very deep they would need lots of light to reach all the way to the bottom at optimum intensity. If a 24" deep tank needs 130 watts for opitimum intensity wouln't a tank half the depth require half the light?

Take a look at this http://hyperphysics.phy-astr.gsu.edu/hbase/vision/isql.html#c1

I'd have to disagree with the statement that a 24" deep tank needs 130 watts for optimum intensity. The depth of the tank is a major factor, but watts of light aren't the best measurement. Several members here have 55 gal tanks with 2x250w MH systems and are reporting excellent results. You will not put enough artificial light on a tank to approximate the natural sunlight that the reefs get. 400w MH systems are not uncommon on 24" deep tanks. I know of one tank, 32" deep, that uses four 400w MH's and three 1000w MH's. Since we're talking about 20g tanks though, I had a coral prop tank with 190w of PC over it. It did require a fan to keep the water temp down, but coral growth was excellent. Anyway, lighting is a controversial subject and it really depends on what kind of lighting you have. 250w of MH is not equal to 250w of PC or VHO. The MH is much more intense because it is concentrated over a smaller area. In the end, it depends on what you want to keep in the tank. If you're just going to have soft corals, you don't need MH. If you intend to have SPS, although you can keep them under fluorescent lighting, MH tends to be much better.

 

[gozetec02]

So if i was to keep Button Polyps and soft corals like that not as much light would be needed. How many watts per gallon would be recommended for button polyp?

 

[vertex]

Even a single 65W PC would probably be enough on your 20 gallon long but it may not light very evenly so I would recomment the 2x65W PC fixtures to get it a little brighter and an even dispersed light. Either would be good for some corals, but most of them even if they will survive with on the 65W would grow better and faster with more light. That allows you to have an 10000K and one actinic as well which will give you much better color...