Is this right? Wpg
 

I've been doing a little reading on lighting and was wondering if the type of bulb would matter for watts per gallon. I am currently running an aquatic life 36" t5ho fixture on a 75 gallon tank that holds 4 bulbs. The bulbs are all different that's why I have this question. 1x67000k coralife, 1x10000k coralife, 1x actinic blue, 1xblue coral I believe. All are 39 watt fixtures. Is it correct to say 4 x 39 = 156 total watts from fixture. So 156 / 75 = about 2.08 wpg. So I have about 2 wpg or my setup. I guess my question is do the colors of the bulb matter? Another question what kind of bulbs would be best for using for my setup as I don't like the yellow water tint from just 67000k bulbs? I do use co2.

Watts Per Gallon was only really applicable with standard tanks and old T8 bulbs. Since you're using a modern fixture, it's something you should completely ignore.

Go here and read through the lighting sticky. Pay close attention to the thread about measuring light with PAR.

Bulb color is all up to you. 6500/6700k seems to be the basic daylight bulb most in the planted tank hobby use. Some use 10,000K and 14,000K bulbs because they like less yellow/more white lighting. But there are all kinds and colors of bulbs available on the T5HO market.

I thought the WPG guideline was only applicable to T12 bulbs; even with the T8 bulbs, the guideline was starting to get a little skewed...

T8/T12/old hat. Point being, the OP has a modern fixture and PAR would be a better measurement.

Your Lighting Question
 

Hello g...

Even though the watts per gallon rule is a bit outdated, it can be a step in the right direction to getting you to the right lighting. 6500K bulbs are recommended for planted tanks. These come closest to natural daylight at 5500K. The color is light blue to the eye.

If you keep to the less demanding plants, then 1.5 to 2 watts per gallon, even using the watts per gallon rule, puts your tank into the moderate light range. This amount will grow more than enough plants and a wide variety to fill a 75 G tank.

CO2 isn't necessary unless you get into the more demanding plants. When you increase the light, you tell your plant to grow faster. In order for the plant to do that, you need to increase the food accordingly.

A nicely planted tank isn't difficult. But, you need to research the plants you want and then give them the proper lighting, nutrients and pure water conditions.

Just a couple of thoughts to consider or not.

B

Thanks that cleared up a lot for me.
Based on those par vs distance charts, they are comparing the fixture itself not the type of bulbs correct? So with my current setup I have more than 50 par making it a high light setup. BTW Both blue bulbs are ATI

I'm trying to grow some hc but there are some plants in there that do not require high light. Would this effect low light plants. I plan on getting some dry ferts as well as some capsules for rooting plants such as osmocote capsules.

Sorry, Watts Per Gallon doesn't work for T5HO bulbs. Please refer to the lighting sticky, BBradbury.

Specifically, the lighting with PAR thread.

It discusses the "myth" of WPG.

Watts Per Gallon applies roughly to T-12, and not too bad to T-8, though it is a little bit off. By the time you get to better bulbs and better reflectors it is so far off that it is not worth asking about.

Like asking how many miles you get from a bale of hay.
When horses were in use, that was a valid question.
Useless when 'horsepower' refers to a car.

If you have a 55 gallon tank, with one of the wood tall light hoods over it, with two 40 watt T12 bulbs mounted at the top of the hood, say 16 inches from the top of the tank, will you have enough light? What if you make some \_/ shaped polished aluminum reflectors to put under each bulb? Suppose instead you sit the bulbs on the glass top of the tank? Surely, no one believes that 80 watts of T12 light defines how much light you have for all of those variations.