# 120p Chihiros Selection; 1x120cm vs 2x60cm vs 1x90cm



## StiekIsOnIt (2 Mar 2021)

*Hi!*
My name is Robin. I am from the Netherlands. Obviously the ukaps forum has been a welcome resource over the past years. I read and searched a lot on the ukaps forum, but couldn't find a suitable answer to my specific question. So I decided to register and ask it here, hoping it would bring me to a definitive conclusion.
To be honest, I've polled this on the r/PlantedTank reddit for the 120cm vs 90cm, which got me a 11 vs 9 voting result. Not significant if you ask me. Well, it makes me Google endlessly!

*My tank*
I own a rimless 120x40x50 tank. I don't have a light for this tank, but Chihiros as a brand has caught my fancy.

*What size light(s)?*
Balasz Farkas from green aqua indicates that a 90cm fixture is enough for a 120p tank at around 7:50 in this video ([link]https://youtu.be/7kOSrg_smy8[/link]). I tend to take his advice on ANYTHING. But with a long lasting purchase like an LED light, I wanted some more opinions, which eventually led me here. I'd love your opinions if you have time!

*Chihiros



*
So I was looking to get a Chihiros WRGB II, of which the 90cm one is readily available to me, but the 120cm is not. The 60cm is also readily available, but I am unable to imagine if that would look bad, since 2x60 equals the width if the tank.

I will be suspending the light above the tank. Either from the roof or with a system.

*The moneys?*
2x60cm goes for 2x€165=€330
1x90cm would be about  €240,
while the annoying 120cm would need to be imported from further away so estimating import tax and such fun would mean
1x120cm would be about €450.

*Budget?*
I have a max budget of 400 euros for a new light. So dual Solar RGB is not an option if you're wondering 🤗, and sadly that also excludes the Vivid 2.

WDYT?


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## Djoko Sauza (2 Mar 2021)

Welcome! 
A full length light fixture would give the sides and corners of your tank plenty of light. A shorter light fixture wouldn't but in my opinion looks nicer suspended.
So I'd say it's up to you and what kind of scapes you're planning to keep.

In my opinion 2x 60cm would just look odd.


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## Paulus (3 Mar 2021)

Green aqua will release a new lighting video shortly. They mentioned it a couple video's ago if i am correct.
But same here. Planning to get a 120cm tank and also still looking for a light


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## oreo57 (3 Mar 2021)

Diogo Sousa said:


> Welcome!
> A full length light fixture would give the sides and corners of your tank plenty of light. A shorter light fixture wouldn't but in my opinion looks nicer suspended.
> So I'd say it's up to you and what kind of scapes you're planning to keep.
> 
> In my opinion 2x 60cm would just look odd.





StiekIsOnIt said:


> *Hi!*
> My name is Robin. I am from the Netherlands. Obviously the ukaps forum has been a welcome resource over the past years. I read and searched a lot on the ukaps forum, but couldn't find a suitable answer to my specific question. So I decided to register and ask it here, hoping it would bring me to a definitive conclusion.
> To be honest, I've polled this on the r/PlantedTank reddit for the 120cm vs 90cm, which got me a 11 vs 9 voting result. Not significant if you ask me. Well, it makes me Google endlessly!
> 
> ...


First thing is are you going to suspend it higher than the normal mounting height?

See if you can find these:
Amazon product


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## Wookii (3 Mar 2021)

The 120cm light will give you the best coverage of course, but a 90cm light may be sufficient, as its only 150mm at each end of the tank - as long as you don't place demanding plants at the ends, you should be fine. The WGRB II is a fairly bright light, but due to the inverse square law relationship between the light intensity and distance, you can't raise it too far above the tank.

If it weren't for your budget restriction though, my default advice would be 2 x Vivid II's which would allow you to suspend the lights much higher due to their output power, and it makes for nicer viewing of the tank from above, and much easier access for maintenance.


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## Zeus. (3 Mar 2021)

Wookii said:


> If it weren't for your budget restriction though,



ADA RGB solar are very very nice, shame you cant control the intensity via controller, for the price you should get an ADA agent to come round and switch them on/off for the first year at least


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## Wookii (3 Mar 2021)

Zeus. said:


> ADA RGB solar are very very nice, shame you cant control the intensity via controller, for the price you should get an ADA agent to come round and switch them on/off for the first year at least



Agreed. I'm hesitant to comment given I haven't seen ADA Solar RGB's in person, but their published spectrum looks to be identical to the Chihiros one, so I'd wager they use the exact same LED's. Given you have complete control over the spectrum, the individual red, green and blue output, and daily intensity scheduling of each channel on the Chihiros app, I really struggle to see a compelling reason to consider the ADA version.


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## Zeus. (3 Mar 2021)

Having seen the ADA solar RGBs at Green Aqua they are the 'DB's' or would be 'if' intensity was controllable, I was very impressed with the specs/vids on the Chihiros when I checked them out some time back. If I was buying I would be looking at them seriously as my present 'dated' Chihiros LED lights was great value for money IMO and easy to control with cheap TC420


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## StiekIsOnIt (3 Mar 2021)

Diogo Sousa said:


> Welcome!
> A full length light fixture would give the sides and corners of your tank plenty of light. A shorter light fixture wouldn't but in my opinion looks nicer suspended.
> So I'd say it's up to you and what kind of scapes you're planning to keep.
> 
> In my opinion 2x 60cm would just look odd.


Ok! Agreed, you confirmed the odd look of the 2x60cm. 
I am looking to go for a wild scape with a lot of hardscape. Most demanding plants will probably be Alternanthera Reineckii, Hygrophila Pinnatifida, but I do want bushy Rotala that turn red. 
Now while those won't be on the sides, it would be a shame if I regret the lights in the long run. 


oreo57 said:


> First thing is are you going to suspend it higher than the normal mounting height?
> 
> See if you can find these:
> Amazon product



Well, depends on what you call normal mounting height. They will be higher than they would be with the brackets they come with. But I think I'll just be going for Chihiros brackets tbh. But I think the link is not for the brackets but for the lights? I don't think I'll go for those, but thanks for the tip! 



Wookii said:


> The 120cm light will give you the best coverage of course, but a 90cm light may be sufficient, as its only 150mm at each end of the tank - as long as you don't place demanding plants at the ends, you should be fine. The WGRB II is a fairly bright light, but due to the inverse square law relationship between the light intensity and distance, you can't raise it too far above the tank.
> 
> If it weren't for your budget restriction though, my default advice would be 2 x Vivid II's which would allow you to suspend the lights much higher due to their output power, and it makes for nicer viewing of the tank from above, and much easier access for maintenance.


I am looking to usu the  brackets from Chihiros, for which I found these dimensions;


<<<< these, would have me end up at ~30 cm above the tank I think.
So not too high. (right?)
And yes, I would love the Vivid 2's, but I need to draw the line somewhere. Also need a second filter and a ton of wood.


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## Paulus (3 Mar 2021)

Here still thinking to get a twinstar.
In the search for information i found these 2 videos (first one to see the difference between the II and III versions)


And another comparison:


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## Wookii (3 Mar 2021)

StiekIsOnIt said:


> Ok! Agreed, you confirmed the odd look of the 2x60cm.
> I am looking to go for a wild scape with a lot of hardscape. Most demanding plants will probably be Alternanthera Reineckii, Hygrophila Pinnatifida, but I do want bushy Rotala that turn red.
> Now while those won't be on the sides, it would be a shame if I regret the lights in the long run.
> 
> ...



I think the standard WRGB II legs put the light at around 100-150mm off the tank rim. Given your tank is 500mm deep, and if we assume say 50mm of substrate, using the supports you pictured above instead will increase the distance to substrate from 550/600mm to 750mm.  if my inverse square law calculations are correct, that would result in a 35-45% reduction in light intensity at the substrate.


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## StiekIsOnIt (3 Mar 2021)

Wookii said:


> I think the standard WRGB II legs put the light at around 100-150mm off the tank rim. Given your tank is 500mm deep, and if we assume say 50mm of substrate, using the supports you pictured above instead will increase the distance to substrate from 550/600mm to 750mm.  if my inverse square law calculations are correct, that would result in a 35-45% reduction in light intensity at the substrate.


I did not know that law.
The example woud be with double distance.;
If we take
600mm = 1r,
1200mm = 2r,
We take 2^2=4. Intensity/4, means 25% of the intensity at double distance. So that works.

My situation would be at best
550 = r, 750=1.364r, 1.364^2=1.86, Intensity/1.86 is .538%. 46.2% loss.
600 = r, 750=1.25r, 1.25^2=1.563, Intensity/1.563 is .64%. 36% loss.

So yea! Nice calcs there!

That seems valid for all suspension systems obviously. I'm assuming the WRGBII still has enough power when at 100%, but might be stretching is. I would want to suspend the 120cm one as well tbh, would you advise against that Wookii?


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## StiekIsOnIt (3 Mar 2021)

Paulus said:


> Here still thinking to get a twinstar.
> In the search for information i found these 2 videos (first one to see the difference between the II and III versions)
> 
> 
> And another comparison:



I believe he's making a Twinstart III vs Chihiros WRGBII video as well.


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## Wookii (3 Mar 2021)

StiekIsOnIt said:


> I did not know that law.
> The example woud be with double distance.;
> If we take
> 600mm = 1r,
> ...



It's hard to say to be honest. The WRGB II's do put out a lot of light. If you accept that Chihiros's PAR diagrams to be accurate:





Then on your 400mm wide tank you're looking at between 90-120 PAR at 550mm depth (not clear whether that's through water or air). With your 46.2% loss, you'll be down to around 48-65 PAR. As I say, it could be lower if Chihiros's measurements are actually in air rather than water, but then you'll also get some reflection off the glass which will give some increase.

It will come down to what plants your want to grow, and only a dense carpet plant might the sufficiency of the light to the test - though again, CO2 might be more important in that case. My gut feeling is you'll be fine, particularly with the 1200mm unit.


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## Paulus (4 Mar 2021)

* by the way is there an option to make these videos smaller in the forum?


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## StiekIsOnIt (5 Mar 2021)

> _Sidenote;_ I was thinking of asking my wife for some more pocket money to get 2 Vivid II's, but decided against it. The new Biomaster 600T, a buttload of hardscape, a 120cm WRGBII; I'll be good to go for the foreseeable future. I'll keep my 400 euro budgetary limit for lights in place



@Wookii I did some more calculations, but I was not entirely about them.
I just used Pythagoras to calculate the diagonal to the edge of the tank, which would net another 3.5 percent loss. But as said, its not fair, since LED is very directional so you'll lose much more in the fat corners. I could not find a reliable function for dissipation of intensity from the center of the LED. 

But then I looked back at your post and saw that image;



So at -15xm,-15cm you'll find a value of ~95. 

R1​1,364​^2 =1,86​=53,78%​CM550​750​
So this, would roughly end you up with a value of 51 given the manufacturers graphs. Well, we can substract a bit more, but that better still better than I expected.  
In any case, your comment is valid, I don't suspect any problems with the 120cm. I actually think it would be the perfect fit for a 120cm tank 😉.

But then in came @Paulus with that video. Quick post there! That was a cool video. Tommy actually talks about putting a 90cm light on a 120p from 20:00. I think he verbalises what we've calculated. The corners get darker, can add to the drama of the build, and it can be something you might be looking for. My interpretation of that though, is that while getting a smaller light can add something to certain specific builds, it must be missing something for most other builds. So it is a less flexible setup.


Together with our calculations, I've reached a decision; 

I'm getting a 120cm light. I think I'll enjoy the flexibility more and TBH, it will give my tank a better look.
I will use it for a number of years and I don't want to be limited by it. 

Thanks for all your help guys! Cheers.


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## Wookii (5 Mar 2021)

StiekIsOnIt said:


> @Wookii I did some more calculations, but I was not entirely about them.
> I just used Pythagoras to calculate the diagonal to the edge of the tank, which would net another 3.5 percent loss. But as said, its not fair, since LED is very directional so you'll lose much more in the fat corners. I could not find a reliable function for dissipation of intensity from the center of the LED.
> 
> But then I looked back at your post and saw that image;
> ...



Yeah, I wouldn't sweat the numbers too much, I think you're making the right decision going with the 1200mm. 

If you want to increase the light hitting the substrate (and also reduce the light spill outside the tank), you can add some reflectors to the edges of the light. I wouldn't use the Chihiros ones, as they will be too wide an angle for your proposed light height, but you can knock up some custom ones with a a mirror polished interior and that will effectively narrow the light beam and mitigated the inverse square losses.


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## Johnwaz42 (5 Mar 2021)

I’m in the UK, can you recommend a good site to purchase either chihiros or twinstar lights please. My tank is 50cm deep running Co2 any other thoughts useful.  Thank you


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## StiekIsOnIt (5 Mar 2021)

I think you're a bit screwed with taxes?
You need to import the light from Asia, basically. So VAT and stuff is an issue. They have the lights on Aliexpress for _cheap_ shipping from Spain or Poland. You then dodge any additional VAT, but I don't think thats true for you because of Brexit. Soooo, I wouldn't know buddy.


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## Zeus. (5 Mar 2021)

Johnwaz42 said:


> good site to purchase either chihiros or twinstar lights please



Aquarium gardens supplies twinstar modes and ADA and has great customer support, well worth a visit IMO


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## StiekIsOnIt (7 Mar 2021)

Was just about to switch to a Twinstar S, since the WRGB2 120cm was out of stock everywhere in Europe.

While I was waiting for a GreenAqua order with my additional filter and painting the cabinet, I figured I had a few days to wait. So googled every day, available nowhere at a normal price or delivery date, buuuut

It just became available from Poland if anyone wants it. Threefitty, so not a bad price either.








						US $383.99 20% OFF|Chihiros WRGB 2 120 Aquarium Lighting Aquatic Plants Sunrise Sunset Aquarium LEDs for Water Plants Fish Tank LED Light Lamp 130W|Lightings|   - AliExpress
					

Smarter Shopping, Better Living!  Aliexpress.com




					a.aliexpress.com
				



 (not an affiliate link if you're wondering)


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## Paulus (7 Mar 2021)

Nice.
Which filter(s) will you use on the tank?


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## StiekIsOnIt (7 Mar 2021)

Paulus said:


> Nice.
> Which filter(s) will you use on the tank?


I already owned a Eheim professional 3 and I'm adding an Oase Biomaster 600 thermo. Heating inside the filter woohoo.


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## Bent17 (13 May 2021)

Hi all very informative thread! 

I am looking in getting the Chihiros WRGB2 also for my 200L tank. The tank is 100cm wide so the 90 would be the one to go for yeah? Also Im scared that by placing the rights on the rim would be a disaster waiting to happen as I could end up dropping the lights into the water..


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## Paulus (13 May 2021)

Did you got the light and if so, how is it?


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## erwin123 (16 May 2021)

I recently got a WRGB2 for my 60x45x45 tank.

I have bunches of stem plants at the back of my tank and there was quite a bit of shadow which affected the leaves of the stem plants nearer the substrate. The stem plants also started bending forward. Fortunately I had a narrow but bright 1" wide Aquazonic LED strip with 15 x 1.5w bulbs  which I put right at the back.

While the diffuser improves the quality of the light and reduces some harsh shadows, it certainly cuts down the light output compared to LED fixtures that don't use diffusers.  As your tank is 40cm wide, I think the WRGB will just be enough to cover the front and back but it might also depend on what you're planting at the back of the tank.


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