# Will adding 2 of the same light, double the intensity?



## Keetchy (12 Jan 2022)

OK this might be an obvious answer but gonna ask the question anyway 😜

I'm only running 1 light, which is a good light for the money. Problem I have is the piece of wood shades parts of the tank. If I move the light to the middle, the MC does good but the Palustris in the back corner is shaded so doesn't grow well. If I move the light back, the Palustris grows well but the MC starts suffering. I'm thinking of buying the same light again and run both of them front and back so all plants are getting decent light.


Would this increase the intensity of light in the tank? Or would it stay the same because the intensity is determined by the power of the output from the light, and I'm not fitting a more powerful output light.


If any of that makes sense 🤔 I'm just worried that if I increase the intensity, I'm gonna struggle with algae as I have a decent balance at the mo which is keeping the algae away 🤞 In a previous tank i had, as soon as I fitted a Twinstar 1200, the algae went crazy and I couldn't keep on to of it so shut the tank down. I don't want that to happen again


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## Mr.Shenanagins (12 Jan 2022)

First of all, great thank! Looks like one of the budget led setups, I think you’d be fine with another one to give proper spread. The solution to the issue with your old Twinstar is a dimmer.


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## dw1305 (12 Jan 2022)

Hi all,


Mark Keetch said:


> Would this increase the intensity of light in the tank?


Yes it will, you will have twice as many photons entering the tank,  and a brighter area of higher light intensity where the light cones, from the two lights, intersect. 

cheers Darrel


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## Hufsa (12 Jan 2022)

If you can dim your light, I would buy the second light for spread, and dim both down 50% (relative to what you have now), then monitor plants and adjust if needed.
Should be fine and your plants will appreciate the added spread


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## Wookii (12 Jan 2022)

As another option, you could also consider buying a more powerful light, and suspending it higher above the tank. It would give you easier access to the tank for maintenance, and would hopefully eliminate much of the shadowing.


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## Keetchy (12 Jan 2022)

Mr.Shenanagins said:


> First of all, great thank! Looks like one of the budget led setups, I think you’d be fine with another one to give proper spread. The solution to the issue with your old Twinstar is a dimmer.


Thank you man. Still a long way to go before its full. Lol. Ah yeah I think I had a dimmer for it as well. I know it started off at about 50% when it came on and then increased to 100% and then started dimming back down again as the day went on. But I still managed to fail with that tank


dw1305 said:


> Hi all,
> 
> Yes it will, you will have twice as many photons entering the tank,  and a brighter area of higher light intensity where the light cones, from the two lights, intersect.
> 
> cheers Darrel


OK yeah that makes sense. So it will only be increased intensity wherever the 2 light cones meet?


Hufsa said:


> If you can dim your light, I would buy the second light for spread, and dim both down 50% (relative to what you have now), then monitor plants and adjust if needed.
> Should be fine and your plants will appreciate the added spread


Good shout, but unfortunately these lights can't be adjusted. All I can do is reduce the time they are on for. Like @Mr.Shenanagins  said, it's a budget LED light.


Wookii said:


> As another option, you could also consider buying a more powerful light, and suspending it higher above the tank. It would give you easier access to the tank for maintenance, and would hopefully eliminate much of the shadowing.


At the moment I can't do either bud. Funds is stopping me from buying a better light in the first place, and I live in a rented place so can't be drilling too many holes in the walls or ceilings. Lol


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## Maf 2500 (12 Jan 2022)

How about alternating your light - one day at the front and one at the back? (Or if you are at home half a day at front and half at back?) Might be enough to keep both sets of plants happy without introducing extra photons...


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## Nick potts (12 Jan 2022)

Mark Keetch said:


> OK yeah that makes sense. So it will only be increased intensity wherever the 2 light cones meet?



Technically yes, if it were me I would treat it as most of the tank is now at a higher intensity.

What brand is the light? You can usually buy inline dimmers or there are more DIY options such as black tape over some for the LED's to reduce intensity. Also, you may need to up your CO2 if you do and another light.

What I did with one of mine is to replace the legs and make them much taller, I used 4mm steel rod from b&q and the light now sits around 40cm over the tank.


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## Keetchy (12 Jan 2022)

Maf 2500 said:


> How about alternating your light - one day at the front and one at the back? (Or if you are at home half a day at front and half at back?) Might be enough to keep both sets of plants happy without introducing extra photons...





Nick potts said:


> Technically yes, if it were me I would treat it as most of the tank is now at a higher intensity.
> 
> What brand is the light? You can usually buy inline dimmers or there are more DIY options such as black tape over some for the LED's to reduce intensity. Also, you may need to up your CO2 if you do and another light.
> 
> What I did with one of mine is to replace the legs and make them much taller, I used 4mm steel rod from b&q and the light now sits around 40cm over the tank.


I like both of these options. Thanks guys. The light is a Jayhill light and I got it from amazon so I doubt they will do dimmers for them. Lol. But I can check. If not, I will try both your suggestions before forking out for another light. The light is only £65 but if I can save myself £65, then happy days


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## Keetchy (19 Jan 2022)

So as expected I am seeing algae growth on the plants. The plants that are suffering the most is the Trident attached to the wood in the middle of the tank. Which I guess is where the cone of light is hitting from both lights combined. I will cut out the algae infested leaves and monitor again. If the algae comes back again quickly, I will put each light on separate timers and maybe only have both of them on at the same time for 1 or 2 hours of the day, the other 4 hours will be just 1 or the other.


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## arcturus (19 Jan 2022)

Mark Keetch said:


> OK yeah that makes sense. So it will only be increased intensity wherever the 2 light cones meet?


No. The total amount of light (photons) that will be available inside the tank will double. In the areas where the light beams overlap the light will also be more intense.



Mark Keetch said:


> Good shout, but unfortunately these lights can't be adjusted. All I can do is reduce the time they are on for. Like @Mr.Shenanagins  said, it's a budget LED light.


Since the lights are not dimmable you should reduce the total time they are on to avoid algae and to damage the plants due to nutrient deficiency. You can get a generic LED dimmer but first you need to first if the lights you have can be dimmed.



Mark Keetch said:


> At the moment I can't do either bud. Funds is stopping me from buying a better light in the first place, and I live in a rented place so can't be drilling too many holes in the walls or ceilings. Lol


I would say that the easiest option is to raise the current lights. You do not need holes in walls or ceilings to raise or suspend a light fixture. Just extend the feet of the light using dyi fittings from an hardware store. Or suspend the light using metal (e.g. aluminium) rods attached to the side or back of the cabinet. Raising the lights would not only improve the light distribution but also reduce the overall light flux that gets into the tank. Then it would be a matter of setting an appropriate light period.


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## Keetchy (19 Jan 2022)

arcturus said:


> No. The total amount of light (photons) that will be available inside the tank will double. In the areas where the light beams overlap the light will also be more intense.
> 
> 
> Since the lights are not dimmable you should reduce the total time they are on to avoid algae and to damage the plants due to nutrient deficiency. You can get a generic LED dimmer but first you need to first if the lights you have can be dimmed.
> ...


OK cool. I can look into raising the lights. So do you think I should go back to just one light and raising it for now, or keep both lights running and raise both of them?


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## arcturus (19 Jan 2022)

Keetchy said:


> OK cool. I can look into raising the lights. So do you think I should go back to just one light and raising it for now, or keep both lights running and raise both of them?


No way to answer that. You will need to check both options. Raising the two lights should help achieving a better light distribution but will also reduce the overall light flux. You need to check if this is still too much light or not because you cannot dim them. You also need to check what is the optimum height since some fixtures spread light on a wide angle. I would test both options with a makeshift setup just to check what works better.


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## Keetchy (19 Jan 2022)

arcturus said:


> No way to answer that. You will need to check both options. Raising the two lights should help achieving a better light distribution but will also reduce the overall light flux. You need to check if this is still too much light or not because you cannot dim them. You also need to check what is the optimum height since some fixtures spread light on a wide angle. I would test both options with a makeshift setup just to check what works better.


Yep I can try that. But for now just reduce the time the lights are on for. Thanks


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## Keetchy (19 Jan 2022)

The only plants that are suffering with algae since the 2nd light was fitted is the MC at the front and the Buce and Ferns on the wood. The stems and Crypts have no sign of algae on then yet


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## arcturus (19 Jan 2022)

Keetchy said:


> The only plants that are suffering with algae since the 2nd light was fitted is the MC at the front and the Buce and Ferns on the wood. The stems and Crypts have no sign of algae on then yet


Increasing the light level will increase the CO2 and nutrient demand from the plants. Have you adjusted CO2 and fertilizers after this change? Algae are a usual result of plants running into CO2 and/or nutrient deficiencies. Unstable CO2 levels also cause similar issues.


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## Keetchy (19 Jan 2022)

arcturus said:


> Increasing the light level will increase the CO2 and nutrient demand from the plants. Have you adjusted CO2 and fertilizers after this change? Algae are a usual result of plants running into CO2 and/or nutrient deficiencies. Unstable CO2 levels also cause similar issues.


Ah damn dude, we could be getting somewhere now. Yes I increased the C02 when I added the extra light, but i never increased the amount of TNC I'm putting in. I am still dosing the same amount as when i was running 1 light. So this would make sense to why my ferns and Buces are getting algae and the MC is going brown (I'm guessing it was algae but it could be dieing)


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## Keetchy (19 Jan 2022)

OK so I got options now. Do I......
1 - Leave the tank with just 1 light but raise it up like in the pic (but not with DVD cases I know LOL)
2 - Stick both lights on and leave them at the height they were at but increase the C02 again and ferts
3 - Stick both lights on, raise them both up and increase the C02 and ferts


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## arcturus (19 Jan 2022)

Keetchy said:


> OK so I got options now. Do I......
> 1 - Leave the tank with just 1 light but raise it up like in the pic (but not with DVD cases I know LOL)
> 2 - Stick both lights on and leave them at the height they were at but increase the C02 again and ferts
> 3 - Stick both lights on, raise them both up and increase the C02 and ferts
> ...


I would start with option 1. This would work with several LED lights in the market. But you need to check if it also works with the light you have. The backup plan is option 3. I would discard option 2 because you cannot dim the lights.


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## Keetchy (19 Jan 2022)

arcturus said:


> I would start with option 1. This would work with several LED lights in the market. But you need to check if it also works with the light you have. The backup plan is option 3. I would discard option 2 because you cannot dim the lights.


Perfect. Thanks for your help bud. Appreciate it. At one point earlier on I was thinking about shutting the tank down.


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## hwscot (19 Jan 2022)

have been pondering something similar. I went with a £30 hygger unit off amazon for my 45cm wide cube. It has fairly basic dimming and timing functions. I've considered adding a second, to give a little more light towards the front of the tank, with the option of running both of them at a lower level or on different timer settings. In retrospect, have wondered if paying more for a light with better control, but in general am pleased with the hygger, for the money. They've now launched a version with much better controls, the 957 which looks great value compared with the big name brands, but seems at the mo to be only available in the US. There are reviews on several US youtube channels, but this one was what I watched.
I'd say, if you do add a second light, there's no obligation to use the same unit as your existing one if you find something, say, at a lower wattage, or with better controls.


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## hwscot (19 Jan 2022)

Keetchy said:


> At one point earlier on I was thinking about shutting the tank down.


oh, no .. it's a really lovely tank .. shame to tear it down


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## arcturus (19 Jan 2022)

Keetchy said:


> Perfect. Thanks for your help bud. Appreciate it. At one point earlier on I was thinking about shutting the tank down.


No reason to shut this tank down. It is already looking good and will look great in a couple of months once you sort out the fertilizers and make sure CO2 is as stable as possible (which is easier said than done). Systems with strong lights and CO2 injection are quite sensitive and small changes can destabilize them, and the end result is often an algae outbreak...


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## Keetchy (19 Jan 2022)

hwscot said:


> oh, no .. it's a really lovely tank .. shame to tear it down


Thank you. And I will definitely look into a dimmer for the lights. It'll save a lot of hassle 


arcturus said:


> No reason to shut this tank down. It is already looking good and will look great in a couple of months once you sort out the fertilizers and make sure CO2 is as stable as possible (which is easier said than done). Systems with strong lights and CO2 injection are quite sensitive and small changes can destabilize them, and the end result is often an algae outbreak...


Thanks man. I gave up far too easily last time on a bigger tank I had, I'll try not to do that again this time. Lol. I'll take baby steps into changes and keep an eye on the effects of the changes


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