[bonjellybean]

Hello, I am in the process of setting up a 75 Gallon aquarium (will be planted) and just finished putting together the lighting. I bought fixture and ballast and 4 T-8's. The T-8's use 32 watts and I'm trying to figure out what sort of intensity I will be getting... as in will it be close to the "2watts/gallon" mark even though the wattage isn't enough? Or higher or lower? The problem is that the lighting puts out 2950 lumens, which is way more than your standard florescent and they have a CRI rating of 87. So, they are great lights but I don't know if they are good enough to get higher light plants or not. I don't want to spend a ton of money and lose my plants. Anyone know how to figure this out??? My tanks is 48"L x 18"W x 21"H

 

[Rex Grigg]

The WPG rule works. T8 bulbs are just bulbs. You will have 128 watts. That gives you 1.7 wpg. And since you make no mention of reflectors you are going to have a low light tank not even close to 2 wpg.

A 2x55 watt AH supply kit would actually put more light into the tank than the 4 T8 bulbs with no reflectors.

 

[SCMurphy]

What fixture did you get to use with the T-8's? Does it have a reflector? How did you wire the ballasts? Have you read the thread on overdriving standard T-8's? Rex is right that two 55 watt AHS kits will put more light in the tank than 4 T-8's without reflectors. If you Set up 4 T-8's and overdrive them 2X with reflectors you will get almost double the standard output and have even light coverage, and enough light to grow anything. My 75 gallon tanks are the only tanks that don't have AHS kits over them. The nice part about overdiving standard daylight bulbs is that replacing them is only a couple bucks.

 

[attack11]

The WPG rule works.

lol. so 5wpg of metal halide is the same as t8 fluorescent, and t8 fluorescent is the same as t5?

wpg doesn't work; it's just an approximation for t8 bulbs to get a good amount of par thru trial/error.

 

[BlueRam]

lol. so 5wpg of metal halide is the same as t8 fluorescent, and t8 fluorescent is the same as t5?
wpg doesn't work; it's just an approximation for t8 bulbs to get a good amount of par thru trial/error.

*In the context of the question asked in the original post.*

 

[attack11]

bonjellybean, read this and this.

you could do the par calc yourself if you're interested in finding out what you'll have, but realistically carbon is going to be the limiting factor.

 

[attack11]

*In the context of the question asked in the original post.*

not at all, since lumens to par can fluctuate drastically between t8 bulbs.

 

[Urkevitz]

I was using 2 t-8 shoplights for a long time and had no problem growing plants. The lighting is more even than PCs.