# Watts per gallon



## Twisted Melon (9 Feb 2018)

How do you work out the watts per gallon for a set of lights?

I searched the forum but can’t find any info. 

Thanks


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## mow said (9 Feb 2018)

first off what are you using the tank for high tech or low tech. what type of lights are you going to use led or t5 . Lights are measured by par not watts per gallon and you need a meter to do so and its not a cheap device. 

here are some links to work out how much light you need.

https://www.ukaps.org/forum/threads/watts-per-gallon.38506/
PAR Readings - what are good readings ? | UK Aquatic Plant Society
Breaking rules | UK Aquatic Plant Society
Par meter recommendations | UK Aquatic Plant Society
DIY PAR meter, Yeah you heard me
DIY PAR meter - Reef Central Online Community
Apogee Instruments Quantum Sensors and PAR Meters - Measuring PPF, PAR and PPFD
Aquarium Equipment: PAR Meters and LEDs - How Accurate are the Measurements? A Comparison of Three Meters and Lux to PAR Conversion Factors for LEDs — Advanced Aquarist | Aquarist Magazine and Blog


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## Tim Harrison (9 Feb 2018)

This may help https://rotalabutterfly.com/light-calculator.php


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## Twisted Melon (9 Feb 2018)

Sorry I should have said about setup. 

I’m going for a high tech tank with led lights.  

I only mentioned wpg because the manufactures seem to always list it, and I’ve only seen a few list the par values, but as I don’t have a meter to test it in my actual setup, it’s not that helpful. 

Cheers for all the links! I’ll have a look at them now.


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## mow said (9 Feb 2018)

tank size and led wattage i can help you with leds as i use them my self on my high tech set up


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## Twisted Melon (11 Feb 2018)

I thought learning about CO2, flow and ferts was complicated! 

Without a par meter, how do I work out the light intensity at substrate level? 

Seems I should be aiming for 50 micromols? Is it trail and error trying to get that?


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## mow said (11 Feb 2018)

lumens per litre 40 to 50 lumens . I have a 160 litre tank which has 7520 lumens which is 47 lumens per litre for my high tech tank.
here is my thread 
https://www.ukaps.org/forum/threads/led-diy.49569/


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## ceg4048 (12 Feb 2018)

Twisted Melon said:


> How do you work out the watts per gallon for a set of lights?
> 
> I searched the forum but can’t find any info.


That's because watts per liter or lumens per meter are irrelevant measurements. A decade or so it was the only guide we could use because PAR meters were (and to some extent still are) beyond the reach of most hobbyists and PAR was generally misunderstood. Any number used on a per volume basis is terrible because of the way light energy decays. The energy decay roughly follows the inverse square rule, so this means, for example, if you measure the energy at a certain distance from the bulb, the energy will be four times lower if measured at twice the distance. It will be nine time lower at three times the distance.

Volume does not take this behavior into account, because it has three dimensions (Length, Width, Height) from which the value can be increased, whereas it is only the Height dimension that really matters.

WPG is therefore a lottery because it is possible to have the same volume in tanks of differing Heights and the energy distribution will vary wildly.. Likewise, it can also occur that tanks can increase in volume but the Height may not increase proportionally, so it has happened that massive amounts of energy is thrown at a larger tank and the result can be devastating.

It is also a fact that the tall a tank is the more difficult it is to get CO2 (which is more important than light by a wide margin) to penetrate to the lower depth and traditionally, hobbyists have ignored this, most important factor. So as you can imaging, the combination of excessive light energy plus the habit of paying poor attention to CO2/flow/distribution led to the recurring issues of poor plant health, which then leads to algal blooms.

When shopping for LEDs therefore, it is always a wise choice to ensure that the PAR levels are published or otherwise known by other hobbyists, and if possible, a controller that enables you to limit the output is available.
When shopping for a T5 or T8, typical PAR data is available such as this:



 

So the idea is to limit the number of bulbs so that you can stay in the blue zone if possible, especially when starting the tank, and only stray into the pink and yellow zones when CO2/flow/distribution is good.

Cheers,


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## Twisted Melon (12 Feb 2018)

Cheers ceg. 

So if I’m reading that correctly, 1 x T5HO needs to be just over 25 inches from the substrate to be in the blue zone?

My tank is only 16” deep. I’m struggling how to work out what I’d need to get going by that graph. Could you give me s pointer please?

Thanks again.


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## ceg4048 (12 Feb 2018)

Twisted Melon said:


> So if I’m reading that correctly, 1 x T5HO needs to be just over 25 inches from the substrate to be in the blue zone?


Yes, that is about right. 


Twisted Melon said:


> My tank is only 16” deep. I’m struggling how to work out what I’d need to get going by that graph. Could you give me s pointer please?


Well this is the problem that arose as a direct result of the emergence of T5 bulbs in the 1990's. If you look at the T8 curve it was very forgiving and multiple bulbs could be used without any worry.
If you have a single bulb T5, and if you are not using CO2 via gas or liquid, then there are simple ways to reduce the energy. For example, floating plants can be used to reduce the penetration. If your tank has a glass lid, wax paper can be used on top. It's just a matter of using your imagination to find ways of blocking some of the light.
The problem with using a single bulb though is that the spread isn't very pleasant. It would be much better to use a couple of T8s.

Cheers,


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## foxfish (12 Feb 2018)

LEDs have only been popular for the last few years, before that, 2 x T8s the length of the tank for low tech & 2 x T5s the length of the tank was the recommended for high tech.
Before T5s.... 2 x T8 for low tech & four x T8 for high tech.
During the early days of this forum, T5s were really popular. Most folk, found great success using the standard recommendations but of course there were the few who had everything right & could use 3, 4 & even 6 x T5s.
Mercury Vapour hanging lights & even Metal Halides have been used but you were always on the edge with these!
I can remember a time when  the new generation of household 12 volt down lighters became popular (maybe 30 years ago) & they were tried as well.
For me, I still favour T5s, however I have problems using my TV remote , so I guess I am old tech in myself!


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## Twisted Melon (12 Feb 2018)

I don’t really have a favourite at the moment between led and tubes. I’d happily get either. 

I do like the controllability of leds. Especially being able to dim them. 

Finding the PAR values for leds is proving a bit of a pain though to be honest. 

I’m considering either Kessil a160we tuna sun or the Fluval plant 2.0. I’ve found the PAR for the Fluval but not the Kessil. Only that it drops sharply outside 45-50cm. 

Plus I’d need 3 Kessil which is kinda expensive!!


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## alto (12 Feb 2018)

@ceg4048 

Any origin or source on that light chart - it's ubiquitous but I've yet to find the "Materials & Methods"


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## alto (12 Feb 2018)

For some reason Kessil requested removal of non-affiliated PAR data - you might request information from the company 
(Sanjay Joshi had included Kessil in his light analyses)

Giesemann also withholds this information (& has proffered reasonable explanation)

T5 is definitely lower cost, though if you want even light distribution across the 45cm tank width, there are some considerations 

I've been running a 60cm x 45cm x 55cm (height) with a T5 fixture, finally switched (temporarily) to a Kessil A160 (the A360 would provide more even coverage if I were buying a light for this tank) & really prefer the access & dimming  control etc, plants seem well enough though there are some shadowed areas that need to be taken into account- I adjusted hardscape etc


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## mow said (12 Feb 2018)

the best way to test led without par meter is lumens per litre but you still wont have a clue what the par value is. What i would do is start of with 5 hours 50 percent power if its too much then lower it and if you do not see any algae and plants are growing as you want them to then leave it as it is. Once the tank has more plant mass then increase the the time to 8 hours and intensity. If you have any problems with algae then you know your light is too much. Take your time as too much light do cause algae and many other problems. I built myself an led light and i have a good understanding of how much light i need to use when i use leds without a par meter.


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## Edvet (13 Feb 2018)

alto said:


> Any origin or source on that light chart


It comes from the USA, the planted tank forum, member Hoppy:
http://www.plantedtank.net/forums/10-lighting/184368-lighting-aquarium-par-instead-watts.html


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## dw1305 (13 Feb 2018)

Hi all, 





foxfish said:


> For me, I still favour T5s, however I have problems using my TV remote , so I guess I am old tech in myself!


I still like T5 lamps as well.

cheers Darrel


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## Tim Harrison (13 Feb 2018)

I prefer the colour rendition of T5s, especially the combo of Arcadia's Freshwater and Plant Pro lamps - they really make critter and plant colours pop - nothing I've seen in LED comes close. 
Although, the new ADA LED - Solar RGB - is supposed to be pretty good; it costs an arm and a leg tho'.

The best way forward with LED is to buy something that is controllable/adjustable - with at least a dimmer - and start off with moderate light, like mow mentions above, and go from there.


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## ian_m (13 Feb 2018)

You can get a rough guide to work out if your new LED fixture is going to be high, medium or low light for your tank volume get a rough idea of watts per gallon.

You should be able to get a lumen output for your LED fixture, either quoted by manufacturer directly or look up the lumens per LED  and multiply by no of LED's. If light is from China or Ebay and not a well known name divide the lumens by at least 2 maybe 3 or 4 as they do tend to overstate the lumen outputs. 

Good quality reputuable makes (Arcadia, Juwel etc) T5 HO tubes generally produce about 60lumens per watt (considerably more light than cheap LED fixtures of course).

Thus you can get rough T5 wattage ratings for your LED light.

Then work out tank capacity in US gallons to workout watts per gallon. This generally assumes the tank is a "typical ratio" where depth is approximately equal to width. Obviously very deep and very wide tanks the Watts/gallon doesn't hold.

Anything above 2W (T5) / US gallon is high light region. Below 1W / US gallon is low light.

For example my tank is 180litres with either 2 or 4 T5 35W tubes.

180litres is 50US gallons.

My T5 lighting is 70W or 140W, thus I get 1.4W/G or 2.8W/G. So four tubes, as I know, are well in high light requiring spot on CO2 and EI dosing and frequent plant trimming and water changes.

This is all a rough guide, to be used in conjunction with cegs graph, to allow you to work out the rough magnitude of tank maintence, CO2 injection perfection, ferts dosing and algae growing you will be heading for.

Generally from my experience a single T5 tube in a typical "ratio tank" (ie depth about same as width) with maybe some foil rings on the tube to reduce light levels (and/or no reflectors) will be classed as low level.


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## Twisted Melon (13 Feb 2018)

alto said:


> I've been running a 60cm x 45cm x 55cm (height) with a T5 fixture, finally switched (temporarily) to a Kessil A160 (the A360 would provide more even coverage if I were buying a light for this tank) & really prefer the access & dimming  control etc, plants seem well enough though there are some shadowed areas that need to be taken into account- I adjusted hardscape etc



 Is that just the 1 a160 you’re running on that rank?

Cheers


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## Twisted Melon (13 Feb 2018)

mow said said:


> the best way to test led without par meter is lumens per litre but you still wont have a clue what the par value is. What i would do is start of with 5 hours 50 percent power if its too much then lower it and if you do not see any algae and plants are growing as you want them to then leave it as it is. Once the tank has more plant mass then increase the the time to 8 hours and intensity. If you have any problems with algae then you know your light is too much. Take your time as too much light do cause algae and many other problems. I built myself an led light and i have a good understanding of how much light i need to use when i use leds without a par meter.



Sounds like a plan mow! There are sooo many variables that I thought I’d just start off really slow, with low intensity and see where I end up. Hopefully not the Algae Forum. 

I think I’ve decided on getting 2 Kessil A160 or 2 AI Primes. 

My first scape is going to be setup so that most of the plants and hardscape are on the left, with them petering out to a bare area of substrate at the right of the tank. 

So I’m thinking I can get away with 2 of the lights instead of 3 to start with, then buy another later on if needed. I can then have the 2 lights slightly more to the left to keep within the 24” spread of the lights. 

Does anybody see an issue with that?

My tank is 54” x 18” x 18” by the way. CO2 injection, EI etc. 

Thanks for all the replies above peeps!!


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## mow said (13 Feb 2018)

so the tank you have is 300 litres. 2 kessils won't be enough as i looked at them and they are rated 40w per light. And also your tank is 147 cm long those kessils won't spread and cover the tank well you will have dead spots. If you are going for a high tech set up i suggest you get at least 120w - 140w led set up.


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## mow said (13 Feb 2018)

A friends tank 120cm x50 x 50 300l using 144w led 8 hours a day full power. Thats a diy led build same as the one i built on one of my threads. The tank is new and still growing.


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## mow said (13 Feb 2018)




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## mow said (13 Feb 2018)

cant leave these pictures here but thats an example of what i was talking about let me know once you seen them i will delete them


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## Nigel95 (13 Feb 2018)

Twisted Melon said:


> I think I’ve decided on getting 2 Kessil A160



If you are planning to use red plants don't choose for kessil. They don't pop reds and you pay relative a lot of money for an outdated spectrum. 

What about a pendant style lighting and go for 2x twinstar s series 600 sp? Only thing is you have 45 cm depth. So maybe you should put the lights a little more to the back so the stems get full light. Carpet plants in front can do with lower light.


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## Twisted Melon (13 Feb 2018)

I’d like a pendant but I’ve no way of hanging it, and none of the universal brackets I can find are long enough. 

Well I did find one, but it’s not something I’d be happy to have in my lounge. 

I’m not really a DIY’er so making one isn’t really my thing either. 

Wish I’d stuck to a standard sized tank now! Ha.


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## mow said (13 Feb 2018)

well buying these leds will cost allot of money in my opinion. My friend was able to build his led for less than 200 pounds i helped him with the build. If he bought 144w leds then it would cost him over 800 pounds. anyways you have a lot of options to choose as nigel said twinstar 600s would be good but your tank size you would need 4 of them.


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## mow said (13 Feb 2018)

I know a guy in poland that builds leds maybe he can build you one for a good price. 

https://www.facebook.com/PowerLedTOMALED/
https://www.youtube.com/channel/UCA3t-6z0FfW-lB4u61_tZvA/videos


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## Twisted Melon (13 Feb 2018)

mow said said:


> I know a guy in poland that builds leds maybe he can build you one for a good price.
> 
> https://www.facebook.com/PowerLedTOMALED/
> https://www.youtube.com/channel/UCA3t-6z0FfW-lB4u61_tZvA/videos



Cheers mow. I’ll have a butchers now.


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## Twisted Melon (13 Feb 2018)

mow said said:


> well buying these leds will cost allot of money in my opinion. My friend was able to build his led for less than 200 pounds i helped him with the build. If he bought 144w leds then it would cost him over 800 pounds. anyways you have a lot of options to choose as nigel said twinstar 600s would be good but your tank size you would need 4 of them.



Wow 4 of those twinstar would be expensive!

Arcadia Classica are cheap. Not sure how good they are like. I could get 4 of those for the price of one Kessil or AI.


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## alto (14 Feb 2018)

Edvet said:


> It comes from the USA, the planted tank forum, member Hoppy:


The chart displayed above predates Hoppy's version by many years 

As to M & M, I was looking for detail such that included by Sanjay Joshi in his Aquarium Lighting articles


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## alto (14 Feb 2018)

Twisted Melon said:


> Is that just the 1 a160 you’re running on that rank?


Yes - I'd picked up an A160 on sale & decided to try it on this tank

I'm still of the opinion that this tank really needs an A360 & was intending to buy one, but decided to wait on the  possibilty of a new model coming (Kessil recently did a discount promo on the A360)


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