# WPG? T5's V T8's and/or T12's ?



## chris1004 (1 Jan 2009)

Hi I am new to this forum and find the whole site fascinating, I have looked elsewhere for the answer to my question but haven't found it but with the plethora of info on the forum it could take me a long time as I keep getting side tracked  .

Anyway I am after some clarification when trying to determine the WPG value of T5 HO flourescent tubes. Do I just count them as (in my case 54w x2) their power rating face value (ie. 108w) or do I add some sort of multiplyer into the equation as I understand that they are upto 80% more light output than a standard t8 tube (i.e 108w x 1.8= 194w equivalent?) . Or was that just sales talk in my LFS  ?


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## aaronnorth (1 Jan 2009)

The shop was right, T5's are 80% more efficient, if you want you can work out the correct sum like you have done or most people just double their answer then take a bit off for quick.


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## Behold (1 Jan 2009)

I never new 2 t5's at 108w was actually nearer 194w when working out the WPG..... or should you just go with 108 is what 2 gives and go with that as a guide???


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## ceg4048 (1 Jan 2009)

All of these measurements are essentially useless but they do serve as a reference and general guide when attempting to determine whether your lighting is low, medium, high or very high. Since T5 lighting appears to be the de facto reference lighting just use it's numbers directly. 2wpg of T5 lighting is enough light to grow any plant and should be considered high lighting. Anything higher than that is considered very high. Reflectors boost the lighting even further but there is no official correction factor for this. T8 lighting as mentioned delivers less energy to the leaf surface so you can get away with higher wattages.

But why do we care about whether the tank is rated as low, medium or high? Well, with low to medium lighting you can away with not using CO2 and with low levels of nutrient addition. With high lighting you will be punished with algal blooms if you don't pay attention to CO2 and nutrients.

You should not get too hung up with being exact with the wpg values because as I said they really are completely meaningless values outside of the context of the general ratings of high energy versus low energy. If you have 100 watts T5 over a 50gallon tank then all it means is that you have 2wpg T5 and that you need good flow, adequate CO2 injection and a robust dosing routine.

Hope this helps.  

Cheers,


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## GreenNeedle (1 Jan 2009)

Behold said:
			
		

> I never new 2 t5's at 108w was actually nearer 194w when working out the WPG..... or should you just go with 108 is what 2 gives and go with that as a guide???



As Ceg says it is getting harder and harder to use the WPG rule or explain what high light is as lights become better.  Even now I am seeing that 8W of high power LED is better than 18W of T8!!!  In 10 years time we wil be saying 0.25WPG is high light. lol

AC


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## chris1004 (2 Jan 2009)

Thanks for your answers guys but the main reason that I am trying to understand how to work out my WPG rating is to try to determine where abouts on the high/med/low scale my particular lighting comes to so that I can understand more clearly many if not most of the threads on this forum which repeatedly refer to WPG when refering to lighting (only an observation not a critiscism).

I understand that there has to be some sort of measure in place or there simply wouldn't be any point of referance to effectivly communicate with, I just wish it was easier to work out (for a numpty like me  ) so that I could then go on to understand more confidently some of the excellent technical pieces on this forum and relate the relevant information to what is actually happening within my own tanks.


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## ceg4048 (2 Jan 2009)

Well it's best to keep things simple so just add up the T5 wattage directly and divide by US gallons. Just round to the nearest tenth and you'll be fine. 

Cheers,


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## chris1004 (2 Jan 2009)

ceg4048 said:
			
		

> Well it's best to keep things simple so just add up the T5 wattage directly and divide by US gallons. Just round to the nearest tenth and you'll be fine.
> 
> Cheers,




If it is really that simple why did I bother getting T5 HO's in the first place when I could have had the same WPG rating with similar rated less expensive T8's?


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## chris1004 (2 Jan 2009)

aaronnorth said:
			
		

> The shop was right, T5's are 80% more efficient, if you want you can work out the correct sum like you have done or most people just double their answer then take a bit off for quick.


 
Not wishing to start an argument but there also seems to be a differance of opinion/conflicting advice therefore I am still non the wiser really.


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## GreenNeedle (2 Jan 2009)

If you take a T12 as being 1 on the WPG scale.
T8 a tiny bit more maybe 1.2x
PC CF as 1.5x
T5 as 1.75x
T5HO as 1.8x
You will be in the ball park there.

As an example:
when I had 1WPG of T8 I got growth at a reasonable rate but the tank still looked quite dark
when I had 1.75WPG of PC CF I got much much faster growth but the tank still looked quite dark in some areas.
I currently have 0.9WPG of T5HO and the whole tank is light and growth if anything is even better and faster than I had with the CF even though it is nearly half the WPG.

Then I have to factor in the different plants I had under each light, the length of photoperiod, differing CO2 injections, different fert regimes, distance above the tank and thats how I come to the (still very rough) multiples I have at the top of this post.

So in essence we know 2WPG of T8 grows anything.  3WPG will carpet well.  Therefore 1WPG of T5HO will grow anything and 1.5-2WPG will carpet well 

The LED test will come soon. lol but will be much harder to work out due to the complicated lighting schedule I will use with it.

The distance above the tank is quite an important one.  stock lighting (within cheap canopies) is approx 2" from the water level in some cases which means that the light will be god where the lights are but the light spread to the eye wil not be brilliant.  When the lights are raised higher the light spread to our eyes may make it look better but the actual light to the tank will be lessened.

Think of a torch.  If you point it at the floor next to you you see a small but bright circle. If you move the beam away the circle gets larger but not as bright.  So there isa balance between getting the spread and retaining as much intensity as possible.  Therefore If you have dark areas then you can raise the light up an inch or 2.  Adding a little more light will maintain the intensity from raising it.  Alternatively raising the light away can lower your WPG if required whilst also giving a better spread. 

So those people who already have more light than they now now they wanted don't need to rip it out and downgrade.  They can just raise their light with the same lights and the spread will be better whilst achieving a lower light level within the tank.  Arcadia suspension kits are only Â£15 from AE or you can use chain and S hooks like I have.  The Arcadia kit will obviously look better.

AC


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## chris1004 (2 Jan 2009)

SuperColey1 said:
			
		

> If you take a T12 as being 1 on the WPG scale.
> T8 a tiny bit more maybe 1.2x
> PC CF as 1.5x
> T5 as 1.75x
> ...



Thanks for the clarification superColey1, just 1 further question though and please excuse my ignorance what is PC CF an abbreviation for?

I have read some posts where  reports of upto 4WPG of T5 HO lighting have been detailed. Do you think they are using the multipliers when they quote these figures or using the more simplified power rating divided by the us gallons way of working it out? Or as i expect would different people be working these figures out in different ways? I am interested in your opinion as to whether some of the figures quoted sometimes should be taken with a pinch of salt or not.


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## ceg4048 (2 Jan 2009)

Hi Chris,
             You've hit the nail on the head when you surmise that different people use different methods. Very few people take pains to use any correction factors. They just divide their wattage by gallons and they get a number. There really is no discernible difference between T5 and T5 HO. A PC is a Power Compact bulb which is the same as a CF which stands for Compact Fluorescent. Examples are shown here: Lampspecs CF 

Lighting is very complicated because it's effects are based on quantum physics and is related to bulb wattage only on a superficial level. The shape of the bulb, the length of the bulb, the distance from the bulb and the color of the bulb all have a significant effect on the amount of energy delivered to the leaf surface in the form of particle energy packets called photons. There are other issues such as distance from the bulb to the water surface, reflectance of the surface light re-strike which cancels output energy. To make matters worse there are optical illusions because the human eye is very sensitive to green wavelengths but much less so red and blue so that bulbs with green content appear to us to be brighter but may not deliver as much photon energy to the leaf. There is no way that any wattage rule by itself can account for all these factors. Few people understand these principles and that's why there is so much confusion and conflict.

What you should take from AC's data is that T5's are generally brighter than T8 or T12. Normal T5 tubes whether marketed as HO or whatever are longer than CF bulbs so that the distribution of light is different and more even per unit area. The same wpg can have vastly different effects in a nano tank versus a large tank simply because of the different area of coverage and the distances from the bulb to the bottom of the tank.

My advice is to take a step back and try to decide what your objective for your tank are. If you want a high growth high tech tank then you can generally achieve that by using 2wpg or more of T5 lights whether normal tubes or CF. If you decide that you don't want to inject CO2 then lower the value to about less than 1.5 or use T8 of similar wattage. Again, depending on your tank these limits can be stretched but only by experimenting with various lighting configurations can this be verified in your particular case. They may or may not be consistent with AC's data.

Cheers,


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## chris1004 (2 Jan 2009)

Thanks ceg4048, that makes perfect sense, mind you I had a bit of a palpetation when you said "quantom physics".   

I have a much clearer understanding of lighting in general terms now than I did. I have been keeping fish for years and have only relativly recently taken the plunge into a showpiece planted tank in my living room and I must confess to rather enjoying the new learning experiences that this branch (pun intended ) of our hobby is offering.

Although unrelated to this topic in general I do have another question with regard to light in that I also have on my planted tank a standard 40W T8 tube which I have on first thing in the morning and last thing in the evening to give a more pleasant subdued light for viewing (i.e. the times we are most likely to be around). Both the twin T5's and the  single T8 tubes are controlled via timers. At present I have the T8 set to give me 4hours of light in the morning and again in the evening and the twin T5's 8 hours of full light in the middle giving a total photoperiod of 16hours (4hours @0.6wpg then 8 hours @3wpg then a further 4hours @0.6wpg (aproximatly  )). Is this photoperiod too long overall for the plants? The plants do grow well and do seem healthy but obviously we all strive to create absolute optimum conditions for our ecosystems and I do understand that each and everyone is different and should be treated on an individual basis. I was also considering leaving the T8 on all day adding to the overall wpg during the high lighting period in my tank but think that it is probably unnecessary at the moment following on from the comments received with regard to the T5 lighting that I have. 

I would appreciate any thoughts / comments / constructive critiscsms that anyone has on the subject.


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## aaronnorth (2 Jan 2009)

This might help a bit: viewtopic.php?f=34&t=2271&p=23845#p23845

16hrs is to long, most people use an 8-10hr photperiod, 12hours being the absoloute max. You can see when a plant has had enough light because some species close their leaves to stop recieving extra light.


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## GreenNeedle (2 Jan 2009)

I would add to what Aaron says that there is no need for 16 hours.  However if you are 'getting away' with 16 hours without algae outbreaks I can't see a problem with it.

It will give algae more of a chance though.

Another thing to add to Ceg's statement is that while without PAR meters etc we are fumbling in the wind really when guestimating these multiples.  Even if wew did know an exact conversion we are still only guestimating what is high and low.

Another thing to add is water clarity.  Dark Water or tannined water will further diminish the light.  If you took 2 identical tanks with exactly the same light. One tank has Purigen crystal clear water and old presoaked bogwood in it versus a tank with new unsoaked bogwood and a tea colour to the water from the tannins etc.  Then the light in the crystal clear tank will be much better.  It will penetrate deeper etc.  This is maybe the simplest thing to sort out. lol

AC


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## chris1004 (2 Jan 2009)

I have noticed leaves closing up particularly on some of the faster growing stem plants which I have quite a lot of. My water is crystal clear and I don't have any major issues with algae but I do have 5 fat otos and a large SAE in the tank as well as a reasonable sized gold nugget pleco who does an excellant job of keeping the bogwood clean.

I am going to reduce the total photoperiod immediatly thanks for the advise.


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## cor2008 (7 Jan 2009)

Hi,
I read that reflectors are already included in working out the WPG rule. If this is right can you remove the reflectors to decrease the WPG rule for T5's (ie i have 2 45w T5's on my Juwel 180, so could I remove the reflectors to decrease the WPG as I only have DIY yeast co2 at the moment. Looks like it could take me another while getting all the gear and my head around pressurised co2    )

Thanks


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## GreenNeedle (7 Jan 2009)

> I read that reflectors are already included in working out the WPG rule. If this is right can you remove the reflectors to decrease the WPG rule for T5's (ie i have 2 45w T5's on my Juwel 180, so could I remove the reflectors to decrease the WPG as I only have DIY yeast co2 at the moment. Looks like it could take me another while getting all the gear and my head around pressurised co2     )



At the end of the day it makes more sense to use less light with reflectors than more light without reflectors.  For several reasons:

1 - Using the same wattage of T8 as T5 will give you less light but more tubes.  This means you can 'spread' the light more over the tank and get light into every part of the tank.  For example in your room there is 1 ceiling light.  Put a 100W bulb in and the corners are still dark.  Get 5 ceiling lights and put 20W then the corners won't be dark anymore and the light will be more even.
2 - Reflectors utilise more of the available light so less waste which means less electricity used to get the same 'useable' light.
3 - It gives you much more options on how much light you have.  You can choose to have 1,2,3,4 T8 bulbs turned on so have 4 different options on 'WPG' compared to 1, 23 on T5 etc.

I am swaying towards options of using more lights rather than less these days whilst trying to retain modern efficiencies.  I do however currently use T5s as I like many went for the latest thinking when I bought them and it is only just starting to turn the other way and as you can see we don't all agree on this much as people didn't all agree on what causes algae and still don't in many cases.

There are many different views on this sort of subject so you won't get one definitive answer because unlike fertilisers where the element stays the same lighting technology advances much like computer technology and as soon as it looks like a definitive answer is close a new technology comes into the mix and we are all back at the start again.

One thing that is not mentioned so much is reflectors.  There is a huge difference between using a T5 tube with a poor reflector compared to using the same tube with a top quality reflector.  Notice I haven't used the words cheap or expensive here.  It doesn't necessarily equate to the cheap ones are rubbish and the expensive ones are good.  There are lots of different ideas out there on reflection using different shapes and angles to using different finishes.  Many assume that the 'mirrorlike' ones will give the best results but from what I have seen the almost white brushed aluminium ones seem to be better.  This is also hard to judge too because it will be hard to find a mirror like one that has exactly the same angle and shape as a polished one.

Difficult subject to answer as you can see. 

AC


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## cor2008 (7 Jan 2009)

> I like many went for the latest thinking when I bought them



haha me too. as i read more & more now im starting to think i have too much light, theres no winning   

i think at this stage i am going to continue with my t5's without reflectors for 8 hours using the diy yeast method (3 seperate bottles) and pray i can keep algae problems at bay (small amounts dont bother me but having BBA or something everywhere would probably eventually do my head in). I will have a fairly good turnover with the standard filter & external tetratec (as soon as it arrives) so am hoping along with a heavily planted well maintained tank i can keep things at reasonable levels. Guess ill see over the next few weeks if i need to get a move on finding all the gear for my fe. 

Thanks AC for that detailed reply, much appreciated


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