# LED Light Issue



## Tanktop (3 Jan 2018)

Hi

Long time reader first time poster.

I have a 120x43x40 200L planted community tank and I have a question regarding lighting. This time last year I replaced my 2x T8s with one Zetlight Lancia. Over the last year all my plants have slowly melted away/ stopped growing. I have Anubias, Jungal val, and Cryptocoryne Wendtii (Bronze I think), all of which were growing like made and I was pulling handfuls out to give to friends.

My guess is the light is the issue as I have not changed anything else from the year before. My question is would a second Zetlight Lancia help? Is it just a case of not enough light or is the light not good enough?

I can’t find many reviews of this light online and was wondering if any of you guys had had any luck with it?

The manufacture clams 4100LM 6500k colour temp blue LEDs 465-470nm, and red 620-630nm., if this helps.

Thanks


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## markk (3 Jan 2018)

It looks like you have roughly halved your light output. So no real surprise that things have changed.

That said, I would still expect c. Wendtii to soldier on regardless (and probably anubias - but I've never grown anubias).

Regards,
Mark

Sent from my A0001 using Tapatalk


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## tam (3 Jan 2018)

Are you sure nothing else has changed e.g. using a substrate that's run out of go or changed hours so your feeding your fish less etc.?


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## Edvet (3 Jan 2018)

Tanktop said:


> not good enough?


Shouldn't be a problem,, Can't judge the amount compared to your  before situation. Sadly some realy subpar LED's are sold too.


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## Tanktop (3 Jan 2018)

Thanks guys. 
I think you right MarkI have just 1/2 my lighting. The Wendtii has just soldier on, it’s just not flourishing like before. 
But as Edvet has just put it, it could also be the light.


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## kadoxu (4 Jan 2018)

When comparing different types of lighting for plants, you should look for PAR (Photosynthetically Active Radiation) measurements and light temperature (Kelvin), everything else (in my humble opinion) is basically worthless.


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## Edvet (4 Jan 2018)

kadoxu said:


> you should look for PAR


Sadly most of the time not provided (especially if the numbers are to low for the price)


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## kadoxu (4 Jan 2018)

Edvet said:


> Sadly most of the time not provided (especially if the numbers are to low for the price)


Sadly true... usually it's up to us to take some measurements and share them with others.


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## Tanktop (4 Jan 2018)

Unfortunately I am now wishing i had done a bit more research in to this last year.
So assuming that my issue is too low a PAR level, will adding another Zetlight help? will this double the PAR levels?


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## kadoxu (4 Jan 2018)

Tanktop said:


> Unfortunately I am now wishing i had done a bit more research in to this last year.
> So assuming that my issue is too low a PAR level, will adding another Zetlight help? will this double the PAR levels?


It will help for sure, but as far as doubling the PAR levels, it's not as simple as that... a light unit will give you different PAR readings depending on distance from the light, light dispersion, light refraction in water and tank walls, etc.

I.e. this image shows PAR readings for a reef tank with 4 light units.


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## markk (4 Jan 2018)

kadoxu said:


> It will help for sure, but as far as doubling the PAR levels, it's not as simple as that... a light unit will give you different PAR readings depending on distance from the light, light dispersion, light refraction in water and tank walls, etc.



Really? The OP is suggesting, I assume, adding another of the same light. This will double the PAR - the details may sway it a few % points either way but otherwise it is as simple as that.

Regards
Mark
(who considered a rant about his pet hate -PAR - but thought better of it!)

Sent from my A0001 using Tapatalk


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## ceg4048 (4 Jan 2018)

Tanktop said:


> Hi
> 
> Long time reader first time poster.
> 
> ...


Hello,
        Modern LED lights typically produce more PAR than the T8 they replace. One cannot tell from Lumen rating as this measurement is not applicable to plants.
Melting plants are symptomatic of poor CO2. You have not specified whether this is a CO2 injected/Liquid Carbon tank or whether this is a non-CO2 enriched tank.

Higher PAR triggers a higher demand for CO2, therefore, contrary to other posters who insist that you have less light, it is more likely that you have too much light.

If your LED comes with a controller, then try reducing the output, or return to using the T8 if you do not have a controller.

Anubias, Crypts as well as ferns and moss can practically grow in the dark, so it is always unlikely that they would fail due to an insufficiency of light.

Cheers,


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## markk (4 Jan 2018)

ceg4048 said:


> Hello,
> Modern LED lights typically produce more PAR than the T8 they replace. One cannot tell from Lumen rating as this measurement is not applicable to plants.
> Melting plants are symptomatic of poor CO2. You have not specified whether this is a CO2 injected/Liquid Carbon tank or whether this is a non-CO2 enriched tank.
> 
> ...



I'm going to do it again....

Really? Are you actually suggesting that replacing two T8s with one averagely spec'd LED fitting is going to increase PAR?

Regards,
Mark

Sent from my A0001 using Tapatalk


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## ceg4048 (4 Jan 2018)

Hi,
    Yes, really. I do not know what "...averaged spec'd LED..." means in comparison to the PAR output of a T8 because I have never measured the PAR of an "...averaged spec'd LED...".
Perhaps you have these numbers or perhaps you have the Lumen/PAR conversion coefficient of this unit, or perhaps you are coming from a Reefer background where megawatt lighting is the norm.

In any case, Anubias does not typically melt under a PAR reduction, usually under a PAR increase without an accompanying CO2 increase.
The OP offers very little additional information about the tank or about his procedures, so I cannot say for certain. 
What I can say for certain is that there are very few occurrences of plants failing due to insufficient lighting, and that Anubias is virtually bulletproof, having a Light Compensation Point of less than 15 micromoles, so the most probable cause is melting due to poor CO2, not due to poor light.

Not sure if this is the same model but this is what I lifted from a supplier website:


> *Zetlight Lancia ZP-4000-1200 LED Waterproof Aquarium Light, 48-56in Plant*
> 
> (**Adjustable color ONLY with the compatible I200 Light Controller & I200R Signal Receiver! - Sold separately!**)
> 
> ...



Cheers,


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## kadoxu (5 Jan 2018)

markk said:


> Really? The OP is suggesting, I assume, adding another of the same light. This will double the PAR - the details may sway it a few % points either way but otherwise it is as simple as that.
> 
> Regards
> Mark
> (who considered a rant about his pet hate -PAR - but thought better of it!)


Yup, really... PAR calculation is not simple maths, it depends on loads of variables. Adding another light will definitely improve PAR distribution in the tank, but as far as doubling the values you get, I wouldn't bet on it.


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## kadoxu (5 Jan 2018)

Also, these lights are specifically designed to replace T8s. This is what the manufacturer claims:
*
Zetlight Model: ZP4000-M-1200-46W*
- Replaces T5 lamps: 54w
- Replaces T8 lamps: 36w

Meaning @ceg4048 is probably (and as usual) right on spot.


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## Tanktop (7 Jan 2018)

Thanks 
I will try ceg4048 suggestion. Liquid carbon is going to be a lot cheaper than replacing the light.


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## zozo (7 Jan 2018)

http://organicsoiltechnology.com/understandinglumens-lux-watts-par.html


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