too much light?

[Andy16]

Can you have to much light for FW plants? Like two 55 watt powercompact lights in a 20 gallon long tnak?

[OrionGirl]

Yes, you can have too much light. Some plants don't like the high watt lights, and will wither away, and there is a limit to how much light the plants can utilize. If the nutrient level is too low, or there isn't enough CO2 available, all the light in the world won't help the plants. And, if this is the situation, you often end up with problems--algaes, browning leaves, etc.

So, 110 watts on a 20 might be too much, or it might be perfect--it depends on other factors. I am running 120 on my 40 right now, and about 100 on a 55. Plants in both tanks are doing well, with minimal fertilization (good substrate for both, though) and a bit of CO2 supplementation.

[mogurnda]

You should be able to keep most plants, even those that like high light levels, with half that light. I use 130 watts for the corals in my 20 reef, but 110W on a 20 FW could be a management nightmare, requiring a lot of nutrient input to keep the plants growing.

[Andy16]

The light im looking at is the 2X55 watt at www.ahsupply.com. I couldnt jsut put one the bulbs in too if its too mcuh light. OR maybe an actinic? It seemed like a great deal for only 65$.

[caffeine]

I have a similar question, with a CF kit like the 2x55 mentioned above with a single ballast, is it possible to control the two bulbs individually? Like install a switch in the wiring going to one of the bulbs so it can be turned on and off while the other still functions? Or you have to have both bulbs connected to the ballast for it to work properly?

[djlen]

Andy, unless you have a lot of experience with lighting and nutrients, I would think twice about going 5+watts/gal. of CF lighting.
It would be a challenge to say the least, for an accomplished aquarist for one. But another good reason is it's totally not necessary. Even the 2x36(over 3/1) would be a big challenge for most people.
Can you give us some idea why you want that much light, other than it being a good deal?
Len

[caffeine]

bigalsonline.com (http://www.bigalsonline.com) has a 55W strip light for $68. Search for ASWO#13151 Ignore the picture, it's only a single tube.

I have a 20L tank as well and it is fairly hard to light these with CF bulbs. There's not really a cheap combination of lighting for a 30" long tank that's not overkill for only 20 gallons. Right now I just have 2 20W regular fluorescent bulbs over mine, but I wish I had a third one.

[Andy16]

I want so much light so i have more options. MAybe if i want a reef someday i wont have to buy different lights again. I figure if it is so hard i could just use one CF bulb instead of the two that i can put in it.

[OrionGirl]

Running a light for 2 bulbs with only 1 in there is hazardous--the empty slot means the fixtures are more exposed to condensation. If water gets in there, it will spark and short, if not start a fire. Not a good plan, IMO.

[Andy16]

Is there a way i can only turn on one bulb then? Then ill just put the bulb in the other slot for the condensation thing.

[OrionGirl]

It depends. The new compacts from corallife that come with the built in fans do have a switch for each light, as well as a plug for each. I hadn't seen any other lights with this option.

[superjohnny]

If you buy the 2x55w kit just don't wire in the second kit... leave it out. I'd contact ahsupply before hand and ask them if that would be an ok idea just to be sure.

You can not run two lights off one ballast and have them on/off at different times. If you want to run them independently you need two ballasts.

[Andy16]

Thanks for al your help guys;) Im going to email ahsupply and ask then about the ballasts.

what if i put a dark blue bulb instead a bright one for the second bulb? would that still be the same?

[Andy16]

I have a better idea now. I will buy the 1X55 watt kit and then if i want anotehr 55 watt ill just buy another one.

[nvision]

my current 20g is doing fine with 65w of pc. before i even added another 55w for a few weeks to speed up the growth of glosso and marselia. i didn't keep that setup for long-term since 6wpg really made me nervous.