[nanocoldwaterfish]

I want to use an led bulb (100 lumens per watt) and around 5500-6500k. I have a severely underlighted 7 gallon tank.

 

[mistergreen]

go for 15-23watts

 

[nanocoldwaterfish]

go for 15-23watts

15-23 watts in what lighting? CFL or LED. wattage is pretty inaccurate for LED lighting as some LED lights can produce more than 100 lumens per watt while others can produce about 85 lumens per watt.

 

[nanocoldwaterfish]

go for 15-23watts

I assume you mean CFL, what would your equivalent in LED will be?
Thanks

 

[mistergreen]

I meant led but Who knows. It depends on the bulb. You have to experiment.
I use PAR, photosynthetic active radiation values From a light.

 

[nanocoldwaterfish]

I meant led but Who knows. It depends on the bulb. You have to experiment.
I use PAR, photosynthetic active radiation values From a light.

Yeah, generally people recommend 2-5 watt per gallon but in CFL. Infact most light wattage measurements on the internet are in CFL. 15 watt to 23 watt led would be way too bright for such a small tank, I guess that wattage in CFL might fit.

 

[tiger15]

I use a LUX meter to measure lumens per unit area at a distance and convert it to PAR. Low light is 30, medium light 50 and high light 75 PAR and above. You can download a LUX meter into your phone for free, and conversion factors from LUX to PAR are available from the Internet.

 

[morenmore]

By coincidence, I was just figuring this out myself.

My example is a 3 foot tank, and I have a AQUA One Tropicglo 28W LED light on it. The product sheet says it is equivalent to 2x30 watt T8 lights. Measuring roughly, I get about 1600 lux at the bottom of the 18" deep tank. Not sure of the exact conversion factor for the LED combination in it ("TropicGlo contains 2 strips of RGB & White and 1 strip of blue LED’") but I reckon that's about 40 PAR. As expected, that's a low to medium light level.