# Fluval Plant 3.0 Hanging Height



## pinchez (29 Oct 2020)

I have a 80L x 50D x 40H cms tank with a 60cm 32w Fluval Plant 3 light. Can anyone advise on the optimum height from the water surface to the light?


Thanks


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## lilirose (29 Oct 2020)

I use Fluval lighting and rest the lights directly on the rim of the tank, and still have difficulty with high-light plants, so I would say "as close as you can get it without permanently submerging it", unless you're happy with low-light plants.


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## pinchez (29 Oct 2020)

lilirose said:


> I use Fluval lighting and rest the lights directly on the rim of the tank, and still have difficulty with high-light plants, so I would say "as close as you can get it without permanently submerging it", unless you're happy with low-light plants.


Is there not a certain height I have to go to get spread from front to back 50cm?

thanks


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## lilirose (29 Oct 2020)

My biggest tank is 90x25x25cm. If it were double that in width, or any higher at all in height, I think I would use two lights (or a more powerful brand).


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## pinchez (29 Oct 2020)

I decided i had my light up too high so i dropped it down to 8 inches above waters surface. The tank itself is 16 inch / 40 cm High and I'll be starting off with easy plants, liquid carbo, Ferts and RODI water remineralised with Salty Shrimp GH/KH


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## tam (30 Oct 2020)

What have you used for mounting it? Looks very neat. I have mine on the tank rim, but I think it needs to come up a bit as I tend to get algae growing around the floating plant roots but not further down in the tank.


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## pinchez (2 Nov 2020)

tam said:


> What have you used for mounting it? Looks very neat. I have mine on the tank rim, but I think it needs to come up a bit as I tend to get algae growing around the floating plant roots but not further down in the tank.


I bought a floating shelf from Argos (£12) and used the spare brace bar that comes with the DD - Jump guard. Cut and drilled a couple of lengths of the bar and screw them to the underside of the shelf with 8cm extending out, the light sits neatly on it 👍


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## chrisfraser05 (2 Nov 2020)

i lowered mine down until there was no light spill on the wall.

if you can get it down that far then light hitting the internal glass will mostly reflect back into the tank. At this point you are wasting about 25% of your light onto the wall and into the room.


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## pinchez (2 Nov 2020)

chrisfraser05 said:


> i lowered mine down until there was no light spill on the wall.
> 
> if you can get it down that far then light hitting the internal glass will mostly reflect back into the tank. At this point you are wasting about 25% of your light onto the wall and into the room.


Thanks for the advise, I’m going to leave it as is for the time being as I’m pretty happy with it but if it needs it I’ll lower it further.

this is a photo from earlier with the light at peak, I’m currently running the planted tank setting from 7am to 10pm including 1 hour either end for sunrise and sunset. I’m going to cut the photo period to 3pm to 10pm with 30mins of sunset and sunrise eventuall.


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## pinchez (2 Nov 2020)




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## oreo57 (3 Nov 2020)

pinchez said:


> Is there not a certain height I have to go to get spread from front to back 50cm?
> 
> thanks


https://store.marinebeam.com/beam-angle-calculator-1/

So for a single row and if you want a "spot size" of 50cm....14.43cm from the diode lens face to the water line us where you would start.
Assume the diodes have a beam angle if about 120 degrees.
For multiple rows just use the radius for front to
back and add the front diode to back diode distance.
Say 6cm fron center of front diode to center of back diode.
So 50-6 =44 /2 = 22cm radius.
So tangent of 1/2 the beam angle =1.73
@13 cm height is approx 22cm radius.
22+6+22=50

Obviously the higher up the less par at the substrate.

All depends on your goals and wants/ needs.
Keep in mind generally the "spot"  is very unequal in light falloff w/ the majority un a small central region and "other things" as explained in my link.

FWHM concept of the beam
So in effect you can go lower than calculated and still gave some light in the entire 50cm at the surface. It will just be low.

Really you only need a starting point and adjust to taste.

For any tank over 40cm deep  2 lights are ususually beneficial unless shallow, say 35cm or less

In your case say 12+40-5 =47cm will be your farthest and weakest light point.

Par has reporteds to be about 63 w a 3" offset and at 19" depth (48cm) with all channels at 100%


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## pinchez (3 Nov 2020)

oreo57 said:


> https://store.marinebeam.com/beam-angle-calculator-1/
> 
> So for a single row and if you want a "spot size" of 50cm....14.43cm from the diode lens face to the water line us where you would start.
> Assume the diodes have a beam angle if about 120 degrees.
> ...



Great information, thanks for taking the time to explain 👍


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## ForestDave (21 Nov 2020)

lilirose said:


> I use Fluval lighting and rest the lights directly on the rim of the tank, and still have difficulty with high-light plants, so I would say "as close as you can get it without permanently submerging it", unless you're happy with low-light plants.


Hi. 
What model of Fluval lights do you use please. I'm thinking of getting the latest Plant 3.0. Thanks


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