Tropical Fish Forums

[AquariumChicky]

Check later post.
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[FloridaBoy]

Hmmm, is this a Quarantine system or a reef system?
20 gallons is really too small for a beginner marine tank, especially a reef system.
If you are doing a QT you don't want live rock or inverts.
Please clarify your goals, and forget about the anemone for at least 6 months to a year.
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[AquariumChicky]

Would 7.5WPG be too much light for an anemone, mushrooms, and possibly a few other corals???
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[djchristone]

wpg rule is crap. same as inches of fish per gallon.

for example, 30 watts over a tank 5 inches tall versus 30 watts over a tank 10 inches tall. say both hold the same amount of water. obviously whatever is at the bottom og the 10 in tall tank is going to get a lot less light

and if you plan on having an anemone, you'll need metal halide lighting pc's or flourescent lighting just doesn't seem to work for them
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[AquariumChicky]

Yeah. I am settin up a 24" 20gallon reef tank. There is a metal halide fixture I want to use but they only sell a 150watt. I figured the anemone would be fine as they for the most part enjoy light, but I wasn't too sure about the mushrooms.
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[dale]

Hey Dj,

If the WPG rule is crap how do you calculate how much light to add to the tank? So you measure and your tank is 5" or 10" deep - how do you then calculate the size of bulb to use?
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[djchristone]

OK the 5" and 10" example is crap. take a 10" tall tank vs a 24" tall tank. the 24" tank is going to have significantly less lighting at the bottom rather than the 10. the lighting will disperse over the water. one can see this example applied to our oceans as well. the sun is the greatest source of light, yet it doesn't penetrate that far down into the ocean does it? even when it gets to the deeper levels, it's really dim right?

so for your lighting, in aquariumchicky's case, she's going to use a mh bulb, 150w, that's pretty much good for anything. some might opt for 250w or once or twice I've seen a 450w mh pendant over a tall tank (which in my opinion is a little extreme) but nevertheless, she's set for anything in a tank like that. I've never had a tall tank before since the only sw tank I his a 12gal jbj nano cube (which I'm going to tear out the lighting in the hood for an external ballast and 150w mh lighting system instead) and a 1 gal pico (soon a 3 gal pico and a 2.5 gal pico...maybe a 5 gal too) so I'd only tell you to be a little careful about placing things on the substrate but I think you'd be fine in most cases for instance, high light clams such as croceas or maximas might need to be placed on the rockwork rather than the sand

er and I think you mean wattage of the bulb rather than size but if she's going to have a nem, which needs very high lighting, mh is a must. but there is no set rule to go by wpg. also consider, bulbs go dim after a while. for example, just because you have 96watts flourescents over a tank doesn't mean it's going to always be 96 watts. after I believe it was 6-8 months, depending on how you use them, they go dim and have to be replaced I believe. also a thin layer of dust could restrict up to half the light coming out of a normal bulb in a house so I would assume such things could also apply here. isn't this why the fish per gallon rule is useless? a 30 inch long carp wouldn't be happy in a 30 gal tank right? there's way too many variables to consider. so this fad, as you stated in the other thread, of having high lighting is pretty much being employed simply so no coral is left out on lighting no matter what level it is in the tank
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[unissuh]

You can actually find 70w metal halides, although from looking up endless online retailers and asking at endless LFSs you might as well go with a 150w MH...70w MH just has too few choices in terms of units and bulbs. You'll probably end up paying the same amount for a 150w MH as a 70w MH. Also, you can just raise or lower the 150w unit to increase/decrease intensity (see inverse square law of radiation) although your electricity bill will be higher.

I like the 'rule of thumb' for MH lighting that says you have one MH per every 2' or 60cm with the intensity dependent on the depth of the tank.

[AquariumChicky]

Thanks everyone.

I had looked into 70W fixtures, but I want an anemone. So. I decided to go with the higher lighting.
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[dale]

illuminating post unissuh
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