How do we calculate Watts?

**anakin** · 8th Oct 2002, 15:42

Urmm..got this problem - I was told by this LFS that the lights he was selling me was 288W. But when I saw the PL bulbs it was 36Wx2x2 = 144W. When I called him back, he said we have to consider the reflector inside the hood which will double the light & therefore Wattage.

Is this true or is this guy taking me for a ride?

**anakin** · 8th Oct 2002, 15:42

Urmm..got this problem - I was told by this LFS that the lights he was selling me was 288W. But when I saw the PL bulbs it was 36Wx2x2 = 144W. When I called him back, he said we have to consider the reflector inside the hood which will double the light & therefore Wattage.

Is this true or is this guy taking me for a ride?

**anakin** · 8th Oct 2002, 15:42

Urmm..got this problem - I was told by this LFS that the lights he was selling me was 288W. But when I saw the PL bulbs it was 36Wx2x2 = 144W. When I called him back, he said we have to consider the reflector inside the hood which will double the light & therefore Wattage.

Is this true or is this guy taking me for a ride?

**anakin** · 8th Oct 2002, 15:42

Urmm..got this problem - I was told by this LFS that the lights he was selling me was 288W. But when I saw the PL bulbs it was 36Wx2x2 = 144W. When I called him back, he said we have to consider the reflector inside the hood which will double the light & therefore Wattage.

Is this true or is this guy taking me for a ride?

**vinz** · 8th Oct 2002, 15:48

Anakin, use the force and go smack him really, really hard please... he's taking you for a long ride on his speeder bike.

**bclee** · 8th Oct 2002, 16:31

Where is this place? We should be careful of this shop.

BC

**anakin** · 8th Oct 2002, 17:42

OK, thanks Vinz &amp; BC. I called back that LFS and asked him on the Wattage again. He said he'll check with his &quot;director&quot; of his company. The guy's got the cheek to ask me to change my cash purchase for someting else from his shop! I, of course, refused flatly. He said that the doubling of Wattage based on reflector is their &quot;practise&quot; (fraudish, I say) ALL these while, and there has been no complains so far.

Well, I'm to call him back on the matter again. If he's not giving me a satisfactoty reply, then rest assure that I'll broadcast this LFS's name FAR &amp; WIDE and bringing up the matter to CASE. I'm just so MAD!

Anyway, does anyone have an official website or book that reptains to this matter - I mean the calculation of wattage and reflectors? Does having reflection increase the wattage of a light source? Technical pple or engineers and even Physics teachers, I need your help here. [

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Thanks a lot guys. Need all your suppot in this time of despair and gloom.

**vinz** · 8th Oct 2002, 18:20

Layman point of view... (I get lost in the world of lumens, PAR, CRI, etc, I'll have to point myself in that direction agian sometime.)

Light and brightness is not measured in watts. Different types of light produce different amount of light with the same wattage. A reflector only diverts the light from a source towards another direction but the total amount of light produced per se is not doubled. The total amount of light going in that direction is multiplied.

If your lights have no reflector... light that shine upwards and sideways from your light tube will all go to waste, and not into your tank. When you add on a reflector, all these 'wasted' light are reflected back, mostly into your tank.

But, you never get 100% reflection (i.e. double the light) for several reasons.
- The reflectability (arghh... what's the right word(s)) and cleanliness of the reflector affects how much light is reflected back.
- The tube and fittings itself blocks some of the reflected light.
- The shape of the reflector and position of the tube affects the angle of reflected light.

Have read some figures somewhere... for a run of the mill FL reflector, the increase is only 65% (if I remember correctly). I think www.ahsupply.com sells one that claims up to 85%. Some LFS here do stock a reflector that claims higher then usual reflection.

**tawauboy** · 8th Oct 2002, 18:37

watts is a measure of power.
for electrical appliance, it is voltage x current.
adding a reflector does not increase the wattage of a light source. the reflector does not consume any power so how can it increase the wattage of your lights.

the reflector will increase the amount of light from your light fixture by reflecting the light from the inner side of the tubes. this increases the lumens of the light fixture, ie, increase the efficiency.

also, there is no 100% reflectance from the reflector. some light is absorbed and turned into heatand some are reflected back to the light tubes. ask the shop to prove that the reflector can double the light output. it will be very interesting...........

**lip** · 8th Oct 2002, 18:52

I don't think that adding a reflector would double wattage. However, it does have the effect of increasing the intensity of the light going into the tank (what do you call that?), which I believe is still beneficial to plant growth.

This is my personal experience. Used to have only 2x30W FL lights for my about 4 ft tank (when i did not know any better). Then I DIY a reflector on the hood by pasting aluminium foil to the underside of the hood. although the reflection is not even, but my plants really started to grow after that.

Just something to share.

**anakin** · 8th Oct 2002, 21:52

So what do plants thrive on - I know its the red section of the Spectrum, but which really helps plants grow - the Watts of the light or the Brightness (the lumens, right?).

What do you guys suggest I do in this case?[

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**lip** · 9th Oct 2002, 10:17

anakin, i suggest you get the neccesary wattage (not taking into account the effect of a reflector) for your tank, together with the reflector. the reflector is always good to have because it will minimise wastage of the light.

hope this helps.

**jacian** · 9th Oct 2002, 15:28

The 36W PL light produces X amount of light. 50% is shined on your tank while the other 50% is shined on light hood. Adding the reflector helps reflect some of that 50% back to your tank. The total amount of lights reaching your tank does not exceed the original X amount.

Anyway, you should pay him half the price and tell him that the notes are double-sided.

**anakin** · 9th Oct 2002, 22:09

hahaha [

]. thought of that too, Jacian. Wanted to give him a note with a mirror and tell him the value is doubled. The whole thing has managed to foul my mood somewhat adversely the last few days, but I'm trying to remain calm. BTW, you're really fast with Teo's planted tank. truly impressed [:0]

But you guys probably won't know how much I appreciate your encouragement and sarcarstic remarks about THAT LFS. kinda solidarity that stops me from feeling lousy about the whole planted tank thingy - for a second I was considering giving uo the whole thing - but decided i will not let THAT LFS stop me from realising my dream

A big &quot;THANKS&quot; again. Will keep you undated!

**anakin** · 11th Oct 2002, 12:29

ALRIGHT!!! THAT lousy LFS has agreed to return my $$$ after all! hahaha

I had to tell them firmly that I'll surface the issue up to CASE if they don't before they go against their &quot;Standing Order&quot; of non-refund.

So guys, do learn from my case - never pay in full initially. BTW, to launch a complaint to CASE, you need to be a member ($25 per year, $400 for life).

Thanks guys! I'll take this amount of cash &amp; go to some more reliable LFS to buy my lights! [

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**M0rph3us** · 11th Oct 2002, 12:34

[

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] all the best in yr hunt for lights.. i think you go nature better..

**vinz** · 11th Oct 2002, 13:57

***? To luanch complaint must be CASE member?!?!?!? Must PAY? What kind of consumer protection is that? Surely there's other ways to prevent fickle or petty complaints.

SHEESH!

**anakin** · 11th Oct 2002, 14:51

Hahaha. Cool it, Vinz. Just take it as a kind of service lah. Not the end of the story, so be calm as you read this ok?

If the sum concerned is less than $10,1000, $10 charge
between $10,000 - $50,000, $20
&gt;$50,000, $50

Nothing in Singapore is free.[

] sad...

Anyway, with justice served and my money on its way, does anyone know whether Chan can custom make a 6x36W PL e-ballast light for me? any other higher wattage PL lights? or has anyone bought/make a light holder that can house 6 PL tubes? I have a constraint - my tank is 45cm from front to back. and I have fans to be attached at the back of the tank. so the light holder cannot go beyond 30cm. Pls keep me inform. appreciate it

**anakin** · 11th Oct 2002, 22:18

BTW Vinz, just thought of this - why not become CASE's member and complain about them charging consumers to lodge a complain? maybe if the suit is BIG enough must pay $50 for admin fees too. [

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