# LED light output - too much ?



## tubamanandy (9 Apr 2016)

Recently solved a big algae problem on my 90 litre (72x35x50cm) tank by reducing the light output on my 28 watt LED light down to 45%.

I notice in the UK that Fluval has just brought out a couple ranges of LED lighting, the Aquasky 16W & 9W ECO Bright both with the ability to reduce the lighting down from 100% to 25%.

Would it be fair to say that my 28 watt LED is well over the top for my size of tank in view of my own experience and the fact that some top manufacturers are bringing out units with much less power ?


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## J Art (10 Apr 2016)

I've got 20 watts of LED over my 38l and it's proving to be too much light. Manageable, but can only squeeze 6 hours with good amount of CO2 before causing issues. 


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## Martin in Holland (10 Apr 2016)

LED watt are still a confusing to me too...how much Watt LED = Watt T5..??? But in any case we should try to know how much PAR they give us.


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## Dr Mike Oxgreen (10 Apr 2016)

Given that the Watts per gallon rule is very, very approximate, and LEDs only produce slightly more light per Watt than T5, you can roughly just apply the rule directly.

90 litres ≈ 26 US gallons.

So with 28 Watts you've got a little more than 1 Watt per gallon, especially taking into account that LEDs do produce a little more light anyway. That's not excessive, and I'm surprised you needed to reduce it as much as you have - except perhaps in the early stages of the tank.

But we also need to know not just the size of your tank, but what fertilisation and CO₂ you're using. Avoiding algae is all about the balance between light, CO₂ and fertilisation, coupled with good competitive plant growth: essentially, light without enough CO₂ and fertilisation will result in algae.


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## id_joker (10 Apr 2016)

medium led...30 lm/l 
high   led...50 lm/l  

medium t5 ...0.5w/l
high   t5 ...0.6w/l


no co2
medium t5...0.3w/l
medium led...20 lm/l


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## AndyMcD (10 Apr 2016)

I've got an 80cm Arcadia Classica LED OTL on (not suspended above) a 140 litre aquarium (80L X 45D X 40H). I'm running CO2.

It's total output is 89W. For me, this equates to 0.6 Watts/Litre.

However, they've measured the output to be 280 PAR at 300mm (see link at bottom of post).

If we say that anything above 80 PAR is high light, then I shouldn't be running this at much more than 30%.

My point is, be careful about creating a general rule, some LED PAR output can be very high per Watt. 

For a relatively new person to this hobby, starting with this light set too high has caused me lots of issues. I think everyone agrees it is better to start with your light set on the low side.

As I have had algae issues (due to insufficient water changes and melting plants at the beginning) I'm still running this light at 12.5%. I think I've read in one of CEG4048 posts that if you have algae issues, you should drop your light by 50%. Glosso is growing leggy indicating low light, but Monte Carlo is doing OK. Rotala is going nuts.

http://www.arcadia-aquatic.com/classica-otl-led/


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## tubamanandy (10 Apr 2016)

Forgot to say as original poster, tank is very mature & I run full EI with CO2 (drop checker is always lime green) and really good circulation and large Eheim external filter.

Going to start cranking the light up but only from 45% to say 55% as its the first time my tank has never had major algae issues for month. 

I really think some of these LED units dont half give off some power and I guess PAR readings would be high on full power.

Strange the new (2nd generation) Fluval LED light units are relatively low powered at 16W & 9W ??


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## AndyMcD (10 Apr 2016)

tubamanandy said:


> Strange the new (2nd generation) Fluval LED light units are relatively low powered at 16W & 9W ??



We've just changed our home lighting to LED. The cost of bulbs is coming down dramatically. Lots of market pressure to make very energy efficient, high output lighting.

Scapefu podcast about Build My LED (US Company) coming out of aquarium lighting to focus on booming terrestrial agriculture market. Lots of demand elsewhere.

My point is, lots of pressure to build more efficient LEDs. Technology not mature. I don't think we should be surprised power consumption of LED lighting is dropping.


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## rebel (10 Apr 2016)

I have 24W LEd and 20W CFL on my 30cm cube and it seems to be enough.  I get some BBA etc but only when the CO2 drops off too much. It depends on the efficiency of the LEd I think. Not all are made equal.


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## Daneland (10 Apr 2016)

For 90 litres 28 watts of LED should not be too much.I have a DIY LED unit and it is 54 watts for my 125 litres.No issue of algea other than some stagnated areas and green spot on the glass.


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## Finn (10 Apr 2016)

I agree with all Andys 

LED systems are incredibly variable - you simply cannot apply a standard rule to them. In my opinion the main advantage of LEDs (aside from their potential cost effectiveness over the long-term) are their capacity to be dimmed and programmed, and I would never buy an LED system without some degree of controllability for the very reason that you are likely to have no idea of it's true output (which is probably more than you'll ever reasonably need in the first place!).

Case in point: I came into the hobby with LED lights to start off. Confused about par and wattage, I followed the watts per gallon thing and decided on a TMC  grobeam 600 for a 60 l lowtech tank, it was only 11 watts so I skimped out on the controller and ran it at 100% thinking it would be fine as long as I dosed liquid carbon... 

Well, lets just say that it's now running at a stable 10%  Enough for my mosses, ferns and bucephalandra without me having to dose liquid carbon and if I'm not being lazy, I avoid most algae issues completely!


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## Chris Jackson (10 Apr 2016)

Yes I agree that LED's add new challenges and without access to a PAR meter it is very hard to know how much useful light is actually being output. Certainly I have had more algae challenges with my LED tank than I've ever had with T5 and Metal Halide lighting. It is however also more exposed to ambient light than my others have been. I have the luxury of 2 x 28w Giesmann Pulzar bars which at full power are pretty darn bright indeed and lead to rampant pearling and problems if run that way for too many hours. I have them computer controlled to ramp up and down and this leads to many new challenges also because there are just so many options. I have to rely on my experience to be able to judge what level is achieving appropriate growth for the plants I have.

So for a complete beginner variable output LEDs add another level of complexity and are hard to advise on, 5hrs at....what power? 
Perhaps what would be useful is a thread where people post their successful lighting regimes with different brands of LED? Could become a bit convoluted but might help? Some sort of shared spreadsheet even?


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## tubamanandy (10 Apr 2016)

Chris, just very curious what power output you are running them both at and your size of tank ?


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## Chris Jackson (10 Apr 2016)

tubamanandy said:


> Chris, just very curious what power output you are running them both at and your size of tank ?



Tank is 60x30x45 and below is my current lighting regime (as of the last month or so) which is working well with glosso and riccia growing happily at substrate level...the crypt parva is something of a BBA farm however but that is a work progress... I was running at much lower output (no more than 65%) over the winter but things were pretty slow.


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