# How many light bulbs?



## Victor (23 May 2022)

Hi there. I'll set up a new tank, a large one, 200 cm X 70 cm X 50 cm (height), 700 L total. What's the best lighting set up, 30 x 7w led light bulbs (210 w total, 16750 lumens) or 40 x 7w led light bulbs (280w total, 21000 lumens)? I'm quite undecided, 30 or 40 light bulbs? Please, let me know your opinion. Thank you.


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## erwin123 (23 May 2022)

If you can afford it, always go for the maximum amount, because LEDs can be dimmed (and run cooler when dimmed).

FYI, my tank is 60x45x45, and I have 156.5w worth of LED.


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## Hanuman (23 May 2022)

Agreed. No much use in counting bulbs. Just get the right size for your tank. Unless you have some very specific requirements, most lights out there will do fine. Chihiros is one example that works well. You would probably need 2 units for that tank size though depending the brand you go for.


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## Victor (23 May 2022)

erwin123 said:


> If you can afford it, always go for the maximum amount, because LEDs can be dimmed (and run cooler when dimmed).
> 
> FYI, my tank is 60x45x45, and I have 156.5w worth of LED.



The problem is this kind of led can't be dimmed. It's a common light bulb, same of the picture below. Despite this, 280 w over 700 L doens't seem to much. The lights will be 8 cm above surface level (light angle is 100º).


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## Victor (23 May 2022)

Here's the lighting scheme. Each black dot will be a 7w light bulb. They will be well distributed over all tank width and lenght. It seems a good idea?


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## Hanuman (23 May 2022)

@Victor Sorry didn't realized you were going the DIY route. I think this is as far as my advise will go. I am not sufficiently educated in DIY lighting. This said, why not buy an aquarium light directly? Is it the cost?


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## Victor (23 May 2022)

Hanuman said:


> @Victor Sorry didn't realized you were going the DIY route. I think this is as far as my advise will go. I am not sufficiently educated in DIY lighting. This said, why not buy an aquarium light directly? Is it the cost?


Yes, because it's too expensive.


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## erwin123 (23 May 2022)

If cost is an issue, it might be cheaper to just buy 5 x 50w LED bulbs. (the plastic frosted cover is removable).
I'm using these 50w bulbs as my video lights.


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## PARAGUAY (23 May 2022)

Have you considered t5 fluorescents as in James C in UKAPS lighting thread. Or floodlights with DIY brackets(MD Fish tanks on you tube)


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## oreo57 (23 May 2022)

Victor said:


> Hi there. I'll set up a new tank, a large one, 200 cm X 70 cm X 50 cm (height), 700 L total. What's the best lighting set up, 30 x 7w led light bulbs (210 w total, 16750 lumens) or 40 x 7w led light bulbs (280w total, 21000 lumens)? I'm quite undecided, 30 or 40 light bulbs? Please, let me know your opinion. Thank you.


78"...185 gallons.
Amazon product

What about some bigger floods over so many small bulbs?

Two 2-packs... 20,000 total lumens.
6500K. 
62 pounds for 4 total lights.  
Amazon product


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## Victor (23 May 2022)

I thought about floodlights but the problem is that the light would be very concentrated over some areas at the contrast of some dim areas (between the floodlights). With numerous small bulbs it's easier to get a more uniform lighting. I think I'll put 210w of led  in total (17 k lumens). It seems enough.


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## Hufsa (23 May 2022)

If you cant make a dimmable DIY light I would at least make sure you can easily raise it further up from the water surface if needed, otherwise youre gonna have a very difficult time getting everything balanced I think


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## Victor (23 May 2022)

Hufsa said:


> If you cant make a dimmable DIY light I would at least make sure you can easily raise it further up from the water surface if needed, otherwise youre gonna have a very difficult time getting everything balanced I think


Unfortunately will not be able neither to dim the lights nor to increase the distance from water .  The light bulbs would be 7 ~ 8 cm from water surface and will remain fixed in a wood cap. So in this case it's better to use less light than more, ins't it? 210 w of led over 700 L is medium light?


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## oreo57 (24 May 2022)

Victor said:


> I thought about floodlights but the problem is that the light would be very concentrated over some areas at the contrast of some dim areas (between the floodlights). With numerous small bulbs it's easier to get a more uniform lighting. I think I'll put 210w of led  in total (17 k lumens). It seems enough.


Yea more is better. I'd convince you otherwise " if" you didn't have that height restriction of  7-8 cm.





						LED Lighting Beam Angle Calculator
					

A simple calculator that determines spot size by a light's beam angle




					store.marinebeam.com
				



8cm up and 100 degrees gives a spot size of 19cm in diameter.
Your pattern is 44 bulbs. 4x11
Your 17.5 and 15cm on centers look ok.
 With that kind of design and even spacing your initial lighting  "may"create a center hot spot though.
Gets  much better with depth.
Advantage of floods is you can uneven space them to actually get a more even spread than you get with multiple bulbs like that.
Gets complicated doing the same thing with many bulbs.
Bulb spacing should be wider on center from the middle getting progressively  smaller toward the edges.  Overlapping cone thing.
See at about 10 minutes in what I mean about floods. Same concept applies for your multi bulb array.


A bit nit picky  and since I haven't seen nor tested that large of an array the "imbalance" may not be that significant.
Second point is s floods can be balanced to avoid hot spots and dim spots.
Actually opaque bracing is more of an issue.
Food for thought.
 Keep in mind cameras and meters are a better judge of these imbalances. Visually you may not notice them.


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## oreo57 (24 May 2022)

As to " how strong is my array " well prefer to measure it. One issue though us since atm you can't t dim it you need to ve cautious at startup if you have a  low biomass of plants.

Water surface average par  est is 134 @ 14000 lumens.
assuming most light is entrained in 14000 sq cm.
200 @ 21000 lumens


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## Victor (24 May 2022)

oreo57 said:


> Yea more is better. I'd convince you otherwise " if" you didn't have that height restriction of  7-8 cm.
> 
> 
> 
> ...


Thank you, Oreo! I made another lighting scheme (look attached picture). I decided to reduce the amount of light bulbs to just 30 (210 w total), they're now more concentraded at the sides to provide a more difuse lighting. Do you think 210 w of led is enough or too little?


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## KirstyF (24 May 2022)

I can’t advise you on the light set up I’m afraid, don’t know enough about DIY ing lights, but would certainly advise that you consider having some diffusion available at outset. Even something as simple (and cheap) as the grey fly netting you can use to make fly screens will act to diffuse light somewhat. If you start out with a couple of layers between light and water surface (and maybe a bit extra spare) you can then add/remove as the tank grows in and stabilises.


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## kayjo (24 May 2022)

You could wire the lights as 2-3 individual circuits.  So, for example, you could have 3 switches on the light.  #1 controls 10 lights; #2 controls 10 lights: #3 controls 20 lights.  This way you could have options of 10, 20, 30 or 40 lights on.


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## oreo57 (24 May 2022)

Victor said:


> Thank you, Oreo! I made another lighting scheme (look attached picture). I decided to reduce the amount of light bulbs to just 30 (210 w total), they're now more concentraded at the sides to provide a more difuse lighting. Do you think 210 w of led is enough or too little?


Yep that is the idea ...
Should be pretty decent medium lighting .
Led efficacy looks to be about 75 lumens/ watt
Depends on what you want to grow.

You could get a cheap lux meter to get a ballpark reading. 
I' m a bit leary on phone apps but I think that depends on the software and what phone sensor they use/ have.


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## achourasweet (9 Nov 2022)

Ok, now I see that LEDs are way better. But how do I choose the correct ones? I just got the tank and need to figure out how to arrange the lights in a way that looks cool in the dark. 
Initially, I thought about a few amazon led light bulbs installed either inside the tank or on top. They are dimmable and can change colors to any I want. I can adjust these just by using my phone and the Wi-Fi connection. I like that I don’t need to get up from my sofa to make any changes. But now I lean towards LED strip lights from the same manufacturer. These are more compact and easier to install.


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## dw1305 (9 Nov 2022)

Hi all,


Victor said:


> Each black dot will be a 7w light bulb.


Can you get LED floodlights*? Have a look at <"(NO MORE) 2,000L High tech BEAST">. They still wouldn't dimmable, but it would simplify the build.

*edit: what @oreo57 and @erwin123  say.

cheers Darrel


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## dw1305 (9 Nov 2022)

Hi all, 


achourasweet said:


> They are dimmable and can change colors to any I want. I can adjust these just by using my phone and the Wi-Fi connection.





achourasweet said:


> But how do I choose the correct ones? I just got the tank and need to figure out how to arrange the lights in a way that looks cool in the dark.


Tell us more, but I think you would be much, much better splitting the two roles, have plant lights for the tank and a separate bulb array (on a time switch) for after dark. The night-time array could just be an LED strip, you can get them as IP65 rated. 

cheers Darrel


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