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Discussion Starter · #1 ·
Hi everyone!

I've often wondered why my duckweed seems to fry in my tank... My tank is a standard 75G. I have a T10 eclipse daylight bulb, the fixture is the Marineland 40 watt fixture with a reflector. The bulb is the "eclipse daylight bulb I think I remember it being 8000K. Behind it is the Marineland double bright Led 36" light. Lights sit directly on top of the glass cover.

Would this be considered low-medium-high light?
 

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If that is only one 40 watt bulb on a 75 Gallon would be considered low light. I have 130 watts on my 75 and I think I am still considered pretty low-med light. Duck weed seems to be growing well.

If Anything you may need some more light. When you say its getting fried what specifically does it look like. How long does is take to occur?
 

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Your Lighting Question

Good morning Norman...

Watts of light up to 1 watt per gallon of tank volume would be considered low light.

The problem with your Duckweed might be the light spectrum. If you switched your 8,000 K bulb with one in the 6500 to 6700 K range. Your plant might improve. GE makes an Aquarium / Plant bulb that's very inexpensive. You can get them at the local hardware stores for about $12.00 each.

I keep having to skim the surface of a couple of my 55 G tanks to get rid of the Duckweed. I have low light, low tech tanks and use a single 48 inch, 32 watt, 6500 K, T8 and the plants do extremely well.

B
 

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As far as spectrum I use 6700K but I've seen folks use 10,000K and be succesful as well so not sure that's the issue.

I said my duck weed was growing well in a previous thread but I meant frog bit. Duck weed is a surface taking over weed. I don't think it needs much if the way of lights or ferts.

What fish are in the tank? Is it possible much of it's getting eaten? I think some Goldies eat that stuff.
 

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Discussion Starter · #6 ·
My other light on the same tank is 16 LED bulbs @ 1 watt each which is rated by Marineland as 1200 lumens which I really don't know how to compare to fluorescent lights.

My duckweed was getting burned (yellow/dry not green and lush like it is in my low light 35G) and sucked into my HOB.

I have 2 HOB emperor filters and a Eheim 2073 on this tank, a powerhead for circulation. Inhabitants are youngsters: 4 Angels, 8 kuhli loaches, 2 BN Plecos, 3 Denison Barb, 3 SAE, 1 Rainbo and four clown loaches. The tank is moderately planted but I'd like to add more and thus my original question.

Is this a low light, medium light or medium high light? There is 56 watts over the tank but 16 of those are LED's and I know they dont quite compare equally to regular fluorescent tubes.

I will do a search on the "Eclipse Daylight tube" to figure out what it rates at...
 

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Hi everyone!

I've often wondered why my duckweed seems to fry in my tank... My tank is a standard 75G. I have a T10 eclipse daylight bulb, the fixture is the Marineland 40 watt fixture with a reflector. The bulb is the "eclipse daylight bulb I think I remember it being 8000K. Behind it is the Marineland double bright Led 36" light. Lights sit directly on top of the glass cover.

Would this be considered low-medium-high light?
You are probably pretty close to medium light. The watt per gallon rule goes out the window with LEDs. Although 1 watt emitters aren't as great as 3 watts.

Good morning Norman...

Watts of light up to 1 watt per gallon of tank volume would be considered low light.

The problem with your Duckweed might be the light spectrum. If you switched your 8,000 K bulb with one in the 6500 to 6700 K range. Your plant might improve. GE makes an Aquarium / Plant bulb that's very inexpensive. You can get them at the local hardware stores for about $12.00 each.

I keep having to skim the surface of a couple of my 55 G tanks to get rid of the Duckweed. I have low light, low tech tanks and use a single 48 inch, 32 watt, 6500 K, T8 and the plants do extremely well.

B
Keep in mind that the watt per gallon rule works best for t8s and power compacts, due to their light output vs efficiency. I advise you throw the rule out the window for anything other types of lighting. Too many people use it for other form of lighting, ending up with serious overkill.

Also, your plants I'll grow hunky dory from about 4000k to 12000k and everything in-between.

The problem with the duckweed is likely the heat from the fixtures baking them. It only has to be warm for it to yellow/ brown. Stick your hand under the lights while trying to keep everything in it's normal position to do a temp check.
 

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Discussion Starter · #9 ·
Thanks jcgd. Youv'e answered my question and confirmed my suspicion. If I wanted to obtain a little bit more light so that I could grow a few more high light pants would there be a way without having to add Co2? I do dose Excel (though I'm not even sure is beneficial with my lighting) and add weekly fertilizer but I don't want to get Co2 due to my fear of pressurized tanks in the home. I would really just like to see my Tiger Lotus to do better... The tank seems to be doing well otherwise, with the exception of my pathetic looking mossball. I have zero algae and everyone is happy.
 
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