# Lights for a 75cm tank



## Epiphyte (17 Feb 2021)

I have a non-"standard" sized tank at 75cm wide and am struggling to find a good light that will work with it. I've used in the past DIY flood lights to great success so I've rigged one up temporarily, but I'd like something a little nicer.

Does anyone know of a 75cm wide light? Would a 60 be too narrow? 90 too wide?

Tank is 45cm deep and I'm growing a Marsilea Crenata carpet with CO2 and lots of ferts.


----------



## Sarpijk (17 Feb 2021)

I I have an Aquael 100 litre which measures 75cm. I have been using a Twinstar 600EA.


----------



## Epiphyte (17 Feb 2021)

How do you find it @Sarpijk? Do you think the 60cm creates strong enough light for a 75? What are the other dimensions?


----------



## Sarpijk (17 Feb 2021)

It is a great RGB light, pretty strong for my no co2 tank so I run it at 50% using a S2Pro led controller.

My tank is 75 x 35 x 40 height.


----------



## oreo57 (17 Feb 2021)

Finnex makes 30" (approx 75cm) lights.
Couple of these would work..
Amazon product
Not sure how 2 would match up to your current light though.


----------



## alto (18 Feb 2021)

Twinstar S 60 (get the new version 3 for better color rendition) should be fine - if you‘re able to go with the SP version, then easy enough to raise the light for better light distribution across the tank length

With fixed leg, you may see some shade effect but it’s only several cm’s on each side (I’m assuming the Twinstar LED array runs the full 60cm or so)

I’d skip the Finnex/Nicrew as individual LEDs will be 0.2watt or less (which is fine for a 30 cm tall tank)


----------



## oreo57 (18 Feb 2021)

First off what a diode is rated isn't always what it's run at
You're right that the Nicrew I listed was a weaker model and I should have thought more about.
Using 2 makes up for this somewhat.
Nicrew sky led is more fitting.


*PAR*: 97 @ 12-inch depth (30-inch fixture)
*Ideal for*: most plant types
*Fixture sizes*: 30-36 inches (available 12-54″)
*For tanks*: 30-36 inches
*LEDs*: 80 White + 15 Blue + 10 Red
*Modes*: Day/night
*Wattage*: 30 watts
.28w per emitter, so prob. .5w " class" leds
But PAR matters more than electrical characteristics.
List:








						[PAR comparison] Best LED lights for planted tanks from small to large
					

Best planted aquarium LED lights with a PAR comparison table and guides for choosing high output lights that grow aquatic plants




					portlandaquarium.net
				




The o/p using led floods could have more or less par than any part. light mentioned
Funnex "standard" planted plus w/ less than .5w per diode:
PAR: 121 @ 14-inch depth (48-inch fixture)
Ideal for: most high-demanding planted tanks, red plants
Fixture sizes: 48 inches (available 12-48″)
For tanks: up to 55 gal
LEDs: (160) 7000K + (88) 660nm red + (16) blue
Modes: Day/moonlight
Wattage: 48 watts .18w per emitter on average not accounting for resistor losses btw


I've never had much love for the likes of 5050 diodes as an example of .2w emitters which were often driven at like .1 w but one can't argue results.
I' m at a disadvantage here since I don't know your market well here.
Heck could have suggested 2 AI Prime freshwaters hung over that tank at the cost of
$200-ish US each.
100 real watts for 2, full control and 90-ish lensing to punch deep  and call it a day.


----------



## Epiphyte (18 Feb 2021)

Any thoughts on the Chihros RGB Vivid II? Looks like it would suit my tank size and results look nice.


----------



## oreo57 (18 Feb 2021)

Epiphyte said:


> Any thoughts on the Chihros RGB Vivid II? Looks like it would suit my tank size and results look nice.





90cm light. 60cm will have less PAR.

Suggest hanging it vs using legs (Depends on leg length)
If you get  a 60cm light for 75cm tank. Just to even out the PAR.
Needs to be about 12cm off the water line.
45 + 12 - 5 = 52cm "effective" height.
Light spill front/back will increase a bit.
Higher it is the more even the light w/ more light loss outside of the tank.
Assumption is you want more even coverage at the top of the tank.


----------



## Kalum (18 Feb 2021)

I've got the vivid on my 75P and it's perfect for this size with good light spread right into the corners


----------



## alto (18 Feb 2021)

oreo57 said:


> First off what a diode is rated isn't always what it's run at
> You're right that the Nicrew I listed was a weaker model and I should have thought more about.


Don’t forget you can buy the same watt rated LED in low and high intensity


----------



## oreo57 (18 Feb 2021)

alto said:


> Don’t forget you can buy the same watt rated LED in low and high intensity


Right, using lumens as a measure you can get, say, 60 lumens/watt to 110 lumens/watt efficiency from different bins of the same diode same manuf and same form factor  much less different manufacturers.


----------



## Epiphyte (18 Feb 2021)

@oreo57 you have knowledge far beyond what I can comprehend! Where do you find the data on these lights or is it all your own work?

I actually found a brand new Vivid II RGB just up the road from me for £280 so I snapped it up, collecting it tomorrow.

I'll have to work out how to hang it though, I may just fabricate something up with some 19mm alu pipe I've got kicking around.


----------



## oreo57 (18 Feb 2021)

Epiphyte said:


> @oreo57 you have knowledge far beyond what I can comprehend! Where do you find the data on these lights or is it all your own work?
> 
> I actually found a brand new Vivid II RGB just up the road from me for £280 so I snapped it up, collecting it tomorrow.
> 
> I'll have to work out how to hang it though, I may just fabricate something up with some 19mm alu pipe I've got kicking around.


Yea good choice.
Here is a contrast manipulated image to show what I was alluding at.
The Chihiros really did  slightly better than the Fluval btw..
It visually will not look like this for a few reasons one of which is human vision "defects"..but this will give you an idea.
Oh, I collect work on retail lights. I build all my own.
The "no dead spots" is kind of my mantra..


----------



## alto (20 Feb 2021)

@oreo57 gorgeous tank 
Hope you’re going to do Journal given those photos


----------



## oreo57 (20 Feb 2021)

alto said:


> @oreo57 gorgeous tank
> Hope you’re going to do Journal given those photos


Not my tank....


----------



## Epiphyte (20 Feb 2021)

I installed the new Chihros light today and it's good.... I think! I've yet to get the colour rendition how I like it, it just feels "wrong", if that makes sense. The colours on my fish really pop though, they're quite stunning, especially the blue edge on the fins on one of my Apistogramas.

I would post a picture but the tank is going through it's ugly stage with fungus from the new wood everywhere 

@oreo57 you mention the light to be hung 12cm off the water line, how did you get to this figure? I've got it perhaps 20cm off right now but it's a little blinding from my sofa with the light bleed.


----------



## alto (21 Feb 2021)

Got Shades? Chihiros - Shade - RGB VIVID II - black


----------



## oreo57 (21 Feb 2021)

Epiphyte said:


> I installed the new Chihros light today and it's good.... I think! I've yet to get the colour rendition how I like it, it just feels "wrong", if that makes sense. The colours on my fish really pop though, they're quite stunning, especially the blue edge on the fins on one of my Apistogramas.
> 
> I would post a picture but the tank is going through it's ugly stage with fungus from the new wood everywhere
> 
> @oreo57 you mention the light to be hung 12cm off the water line, how did you get to this figure? I've got it perhaps 20cm off right now but it's a little blinding from my sofa with the light bleed.


Estimated from the normal beam angle of the diodes and maximizing for right left coverage at the water surface
The glare factor is known and they sell shields for it.








						8.09￡ |Chihiros Light Shade Reflect Hanging Stand For Wrgb 2 Led Lamp Aquarium Accessories Hanger Free Shipping - Lightings - AliExpress
					

Smarter Shopping, Better Living!  Aliexpress.com




					www.aliexpress.com


----------



## oreo57 (21 Feb 2021)

Epiphyte said:


> I installed the new Chihros light today and it's good.... I think! I've yet to get the colour rendition how I like it, it just feels "wrong", if that makes sense. The colours on my fish really pop though, they're quite stunning, especially the blue edge on the fins on one of my Apistogramas.
> 
> I would post a picture but the tank is going through it's ugly stage with fungus from the new wood everywhere
> 
> @oreo57 you mention the light to be hung 12cm off the water line, how did you get to this figure? I've got it perhaps 20cm off right now but it's a little blinding from my sofa with the light bleed.


Actually my math was way off. Not sure how I got 12 (may have somehow doubled my should have been est of 6cm) but here is a corrected graphic of various heights and light  err "cone"
I'll blame it on the metric system...
I assume 12" width (75x30).. height is irreverent.
Keep in mind that the edge area around an ind. "cone" will be considerably duller than the center area.
You can see the issue w/ 20cm..




You can use this calculator to get an idea of the spread of the light.
It will give you a diameter but you only use the radius
Example you light surface is 60x14cm
At a throw distance of 6cm the diameter of a single 120 degree lensed diode is 20.78cm
So your spread is
10.39 + 60 + 10.39 = 80.79
10.39 + 14 + 10.39 = 34.78
(yes just add diameter plus light )
LED Lighting Beam Angle Calculator

Once the light is in the tank it is "trained" by reflection/refraction.
Hopefully I got this right .. but the concept is sound.
Oh and to give you a number ..at 20cm your "cone of light" is 129 x 83.3cm..

Edit: Looking over my older post and I can see that I was concentrating on evening out the PAR which does change things a bit.. 
That's my story at least.. 
Split the difference.. 9cm..


----------



## Epiphyte (21 Feb 2021)

alto said:


> Got Shades? Chihiros - Shade - RGB VIVID II - black


Nope I do need to get them, but sadly Aquasabi aren't shipping to UK right now and Green Aqua shipping costs are a little high. I'll lower the lights to see if it helps but it's not the end of the world. I've got some 1.5mm aluminium sheet lying around so I could make something myself until I find an easier source of shades.



oreo57 said:


> Actually my math was way off. Not sure how I got 12 (may have somehow doubled my should have been est of 6cm) but here is a corrected graphic of various heights and light  err "cone"
> I'll blame it on the metric system...
> I assume 12" width (75x30).. height is irreverent.
> Keep in mind that the edge area around an ind. "cone" will be considerably duller than the center area.
> ...



Thanks @oreo57, this sort of stuff is fantastic information which is a little beyond what I would have worked out on my own. I'll drop the lights to 9cm and see how it goes. The corners of the tank mostly have stems in them so lighting isn't as crucial as the centre which has carpeting plants, so I can sacrifice a little corner light intensity.

Thankfully I've made some convoluted aluminium extrusion light fixing which is really adjustable for height, even beyond what the suspension wires can give.


----------



## alto (23 Feb 2021)

Don’t forget that as you reduce light intensity (running at say, 60% vs 100%), light distribution pattern also alters 
(this pattern is easy to see with a Kessil over an empty tank in a dark room)


----------



## oreo57 (23 Feb 2021)

alto said:


> Don’t forget that as you reduce light intensity (running at say, 60% vs 100%), light distribution pattern also alters
> (this pattern is easy to see with a Kessil over an empty tank in a dark room)


Don't think the pattern changes, just gets more visible to the eye..
Gamma Basics

Like you can spot differences between 20% to 10%  then 100% to 50% 
Whole thing is complicated..








						GUIDE TO TIR LENSES - LEDiL
					

WHAT IS A TIR LENS Most typical lenses in the LEDiL standard product range are the cone-like lenses. These lenses are often called TIR lenses as a big part of their design relies on total internal reflection. Typically TIR lenses are rotationally symmetrical designs which give a nice round light...




					www.ledil.com


----------



## alto (23 Feb 2021)

oreo57 said:


> just gets more visible to the eye..


perhaps ... but my plants also noticed - shade is shade


----------

