What's my wpg?

[nickmcmechan]

OK, so I have 3 x 25W fuorescents (specific plant type) over my 55G, giving me ~1.5wpg

I have refectors over each bulb, the reflectors (parabolic shaped) claim to increase output by 100%.

Does this mean, in effect, I have the equivalent of 150W over my tank, i.e. ~3wpg?

 

[Plecosterone]

No. You still have only 75w. The reflectors only help re-direct the lighting into the tank. Light from bulbs goes up, to the side, as well as down. The reflectors just re-direct the light where it is usable (into the tank instead of all over the place.

 

[nickmcmechan]

so, if i didn't have reflectors, but had 150W over the tank, would the plants recieve as much light as my current state of play, i.e. 75W with reflectors?

 

[Plecosterone]

In theory? Probably, but the only way to to tell is with a meter. Most people want as much light as needed for as little as possible (cost, maint and electricity). It is always better to use reflectors and get as much light coming off the bulbs into the tank. But you could use higher light and have a lot wasted into the air and still grow plants as long as they get enough.

 

[nickmcmechan]

therefore, theoretically, on the assumption I have good relectors, i have in effect, 3 wpg?

 

[Plecosterone]

No. You cannot get 150watts out of 75. The reflectors just let you use more of that 75 watts giving you close to 1.5 wpg since reflectors will not reflect 100% of the light.

 

[nickmcmechan]

ahh, i see...so have i wasted my money...i started off with 2 x 25W with refectors, how much additional benefit do i get from the additional 25W with reflector...

the cost was about $80 for this additional bulb (cost of bulb, reflector, starter unit and glue)

 

[Plecosterone]

You get an addition 25 watts of light if the reflectors are any good. Manufacturers can claim almost anything but in reality most is not very true. The best reflectors I have seen ( I do not use them but many in here do ) are from AHsupply.com.

 

[nickmcmechan]

so, the claim that the reflectors will double light output is probably false?

 

[Plecosterone]

Double output = FALSE. Doubling light into the tank = PROBABLY TRUE.
The only way to get more usable light out of a NO flourecsent is to overdrive it with an electronic ballast. Simply put it puts more power into 1 bulb and therefore increases wattage. Bulb life is not as long and some people don't like doing it for safety reasons but it perfectly safe if done properly. I use overdriven bulbs on my 75 and 90 gallon tanks.