Wpg And Compact Fluorescent Lights?

[vonjankmon]

I've heard that most of the time when people are talking in WPG for plants they're usually saying it in terms of a T-8's and I've heard that Compact Fluorescents are more powerful.

First, is this true?

And if so is there any kind of guide as to a decent conversion?

The lighting setup for the new tank I am putting together uses dual tube Compact Fluorescents and I want to make sure that I'm working off actuate information on how it works.

 

[Luketendo]

I think it's true.

I think 2 WPG of T8 is worth like 1.5 WPG of T5.

 

[chr15_8]

i thought i read somewhere that the wpg rule was designed when people where ising t12's? so even when you said you had 2wpg of t8 it was actually higher?

but yes t5 is better than t8.

 

[SuperColey1]

The second poster has got his figures the wrong way around. T5 is more equivalent to WPG rule than T8.

The WPG was calculated on T12

There is no exact conversion rate for the sifferences of light as it isn't a strict definition. If you have a 24W T8 that is the width of the tank compared to a 24W PC which is shorter but much more power you will have the central area where you have maybe 3x the amount of light whereas at the ends of the tank the PC will probs be ½ that of the T8 due to its shortness.

Overall if you have like for like wattages i.e. 4 T8s the width of the tank versus 2 PCs Left and right so that both the T8s and PCs are covering the length of the tank I would estimate that you could be looking at as much as 1.75x the equivalent T12 on the WPG rule whereas the T8s could be 1.25x

This assumes that you have a proper PC reflector as PCs are a ***** to get good reflectors for.

There is no strict definitive guide and these figures are total guesses as the whole calculation would involve light meters etc which I dont have and also relies on the user having reflectors designed for the type of tube you are using.

Assuming you were using the same brand of tube, the same type of light (ie spectrum), the same wattage etc the differences could be as much as follows:

T12 = 1WPG (<------The WPG rule)
T10 = WPG x 1.1
T8 = WPG x 1.25
T5 = WPG x 1.5
PC = WPG x 1.75
HO T5 = WPG x 2

These figures are purely speculative to say the least and are in no way me saying they are right. They are just my best guesstimate from the observations that I made from the switches I have made from T8 to PC to HOT5/T5HO. I have filled in the spaces in between of the lights I haven't used with no observations made.

From my observations though I prefer T5 linear lights or HO than PC due to the fact that they spread the light much better. Reflectors are also much easier to come by than the PC ones. The PC light when I used them gave so much light to certain areas and not others leaving some plants in swathes of algae whereas others wer trying to bend in towards the light or dying off. With linears you can space the tubes much better in your hood to spread the light whereas PC lights you are stuck with double tube in one area this is an example of what I mean (excuse the bad drawings)

Both of these example are using the size of my tank and trying to get equal wattages over it for the 2 types of unit. (Light intensity is shown as Green-yellow-cream-Red-Pink with Pink being high intensity)

This is an example using 4 tubes each being a 29" HO T5 30W = 120W. These tubes go from end to end in my hood.
You can see that the light is fairly evenly spread over the floor of the tank as the tubes are nicely spaced out from back to front

This is an example using 2 tubes each being a 21" PC 55W = 110W. These tubes are 9 inches shorter than my tank therefore the ends will be darker.
You can see that the light is reasonably spread over the floor of the tank but due to the fdact the 2 tubes are together has meant that there are some super intense lighting in vertain sections looking from the side whilst there will be some fairly shaded parts at either end of the tank due to the tube length.

These diagrams are in no way scientific. Just meant to show what I mean. When I used PCs I found that under the pink section every stem plant I grew like Rotala/Ludwigia would double in height each week BUT would be covered in algae due to the intensity of the light as it was growing at its top speed. I assume it was maxing out and could not go as fsat as the lights were providing for!!!

Under the HOT5 the growth is more equal across the tank. Still quite fast but a much more even growth.

Andy

 

[jollysue]

I am guessing that the PC is Compact flourescent?

I have a long way to go! I have some of each type. I have liked the t-5s. I didn't know about the compacts, but got one awhile back. I haven't used it yet for growing, but have chucked my new plants from ICEEGRL in that tank. It is a 30" 20usg L tank with a 30" light hood and one 2 x compact. The bulbs in it are 1 blue and 1, I assume, 10000 K. Should I change that or which type of tank should I use it on--like full planted or just Java moss and sword or show or what?

 

[SuperColey1]

I am guessing that the PC is Compact flourescent?

I have a long way to go! I have some of each type. I have liked the t-5s. I didn't know about the compacts, but got one awhile back. I haven't used it yet for growing, but have chucked my new plants from ICEEGRL in that tank. It is a 30" 20usg L tank with a 30" light hood and one 2 x compact. The bulbs in it are 1 blue and 1, I assume, 10000 K. Should I change that or which type of tank should I use it on--like full planted or just Java moss and sword or show or what?

Yes - PC is power compact which is sometimes labelled compact fluorescent

Do you mean it is a twin unit (2 x 65W) or 1 unit with blue one side of the tube and white the other.

Either way I would take the blue actinic out. That is a marine lamp. You should replace it with a pink and then the white in the other will balance it out.

If it is 2 x 65W then that is one hell of a lot of light over a 20USG (6.5WPG x ?) and this is going to spell trouble.

If they are independently switchable then I would just use 1 lamp for your photoperiod and if wanted the other for 2 hours in the middle (noon burst)

Under that kind of light you are going to need fast growers, proper dosing, pressurised CO2 and at least 80% substrate covered in plants!!! otherwise it will be green/brown with algae within a week.

Sorry to disappoint you here.

Andy