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DIY light builders, how much is enough light?

Epiphyte

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Joined
15 Dec 2020
Messages
90
Location
Hemel Hempstead
I'm a bit of a DIY fan so the idea of building a light instead of buying one seems fun. I understand the light is unlikely to compare to something like a Twinstar or ADA light but my tanks aren't growing the most difficult plants if I'm honest.

I'm currently running my first DIY light which is 3x 25w LED flood lights, 6500k, which equates to approx 7500lm. I know "lumens are for humans" but it's the only quantifiable number available easily, PAR is hardly advertised as we all know.

The 3x 25w lights give a nice looking tank, lots of bright and shadow but I feel with a 60cm deep tank they're just not reaching the bottom too well for the carpeting plants. Also, given the beam spread, I'd like to raise the current lights a few inches but this will cause the light to become even dimmer, or should I say spread out wider and thus reducing the penetration through the water column. I'd like to up the lighting with some brighter lamps. Going by Tropica's advice, I should be looking circa 40lm per litre, so in my case 14,000lm in a 350L tank.

Does this sound right? Seems awfully bright to me? Given Something like a twinstar 1200 SA is less than half of this? Yes I know all light is not created equal, but as figures go, this is significant.

So DIY aquarists, what is your advice with this?
 

Nick potts

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Joined
25 Sep 2014
Messages
464
Location
Torbay
As you say all light sources are different, and when you mix in mon aquatic lights it gets harder.

The best advice I can give is to try them and see, sometimes stats and figures don't really help.

Sorry not much advice on the actual lights :)
 

jaypeecee

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Joined
21 Jan 2015
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1,713
Location
Bracknell
Hi @Epiphyte

I seem to recall that @zozo has quite a bit of experience with DIY aquarium lighting. I have linked him here so he will hopefully see this thread. Regarding the conversion of lumens to PAR (PPF*) and other lighting calculations, etc., you may find the following to be of interest:


* PPF = Photosynthetic Photon Flux

JPC
 

zozo

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Joined
16 Apr 2015
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7,642
Location
Netherlands
I did build quite a few lights from different LED types, but never for tall aquariums... Thus i have absolutely no experience with that. For relative shallow aquariums max 35cm it's relatively simple and easy to make sure you have more than you need and use a dimmer.

For tall tanks i suspect using some logic, it's best to choose for strong and compact light sources such as COB LED units. These give a higher concentrated narrow beam of light. The DIY downside is, because of the high performance at such a small footprint they get relative hot and could require adequate cooling, by means of a heat-sink and or fan cooling. This will bring some extra cost with it, the proper heat-sink could be relative expensive... The best price to get around this i guess, is stay with the LED floodlights but increase the output. Make it 50 watt instead and maybe take one extra. These are constructed to handle the heat. No need to spend much more with a DIY reinvention of the wheel.

Maybe this can bring you some ideas... @Filip Krupa uses 9 x 50 watt COB LED floodlights above his beast. And the thread speaks for it self, it seems to grow plants like a champion.
 
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Filip Krupa

Member
Joined
13 Oct 2016
Messages
603
Location
Liverpool
I'm a bit of a DIY fan so the idea of building a light instead of buying one seems fun. I understand the light is unlikely to compare to something like a Twinstar or ADA light but my tanks aren't growing the most difficult plants if I'm honest.

I'm currently running my first DIY light which is 3x 25w LED flood lights, 6500k, which equates to approx 7500lm. I know "lumens are for humans" but it's the only quantifiable number available easily, PAR is hardly advertised as we all know.

The 3x 25w lights give a nice looking tank, lots of bright and shadow but I feel with a 60cm deep tank they're just not reaching the bottom too well for the carpeting plants. Also, given the beam spread, I'd like to raise the current lights a few inches but this will cause the light to become even dimmer, or should I say spread out wider and thus reducing the penetration through the water column. I'd like to up the lighting with some brighter lamps. Going by Tropica's advice, I should be looking circa 40lm per litre, so in my case 14,000lm in a 350L tank.

Does this sound right? Seems awfully bright to me? Given Something like a twinstar 1200 SA is less than half of this? Yes I know all light is not created equal, but as figures go, this is significant.

So DIY aquarists, what is your advice with this?

Defo doable, and cost effective.
my flood lights are indeed 50w each. just to give you an idea, ive 9 of them over a tank area of 1700mm x 1700mm, at a height of 70cm from the substrate.

I remembered getting baffled by par/lumens etc, ended up finding a document which had actual par of those floods at several distances but I still pretty much eyeballed the nr of floods and the wattage.

Pearling even at substrate!
One thing I wish I did different is a warmer light colour, I was into cool whites at the time, but not anymore.

good luck,
drop me a line if youve any questions about my setup

Fil
 

oreo57

Member
Joined
19 Jun 2020
Messages
145
Location
USA
For more accuracy start with this to get an idea of height/beam angle needed

30cm from light to water surface and wanting a 45cm "spot" size you want a 74 degree beam angle.

If you don't coordinate your tank dimensions and desired height of the lights to your lighting it gets even more difficult to estimate par at depth due to light spill outside the aquarium
Once you get that down shooting for 90 actual watts total is a start
So assuming a standard 45cm wide tank 45 cm from waterline to face of bulb use 3 lights like par30s and high cri in the 5000 to 6500k range 50 degree beam angle.
30w each.

Using high cri COBs is easy though a full blown diy project. Without out lenses these should be about 13cm off the water. Native beam angle of about 120 degrees...
Above assumes one wants overall tank coverage from top to bottom, left to right.

Example, 5 of these 54cm off the water line

5000k, bit low in cri at only >80.
8500 total lumens. Line voltage dimmable.

Looking back your current lights may be fine if height adjusted correctly.

15248 lux at the water surface if you keep most of the light inside the tank water surface.
271 Par.
Should hit >50 par at the bed.
 
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