Another light question red/green

[mark freshwater]

Hi,
im still trying to decide on led lighting for a reef coral tank, soft/hard coral.
A question about red and green leds,
Are they necessary?
im looking for a 4ft light/lights there are so many choices ,
ive been looking at the cheaper BB's which look great but i would have to make a bracket for the mars aqua or viaspectra etc, as im renting and cant drill holes in the roof.
Is the red and green that noticable ? because there are alot of cheaper lights with a 4ft housing but only have white and blue, 10 years ago when i had my last tank it was a T5/compact floro with white and blue, i had corals and never had a problem but would like led.
I want to make sure i dont get caught up in the hype and spend more money for different colors and a hanging light that i dont need /have to make a bracket for.
I nearly ordered 2x 165w marsaquas today then thought i would research more ,
also ive noticed that alot of people say you need 2x 165w units on a 4ft with 2-3w leds and smaller wattage lights (not led bulbs) will not cut it , but then they run there lights on like eg 40-70% ,
so if running them at a lower % to stop corals bleaching etc wouldnt it be easier to get lower wattage.
Also if getting a light with a housing that sits on top of the tank can it be lower wattage (are higher wattage lights built with more watts because they hang 8-12 inches above the tank?
Still confused .
thanks mark

 

[mcarroll]

You're asking exactly the right questions about exactly the right things.

Red and green is where all the hype is, so there aren't very many blue plus white fixtures left on the market.

Of the ones that are left, most seem to be designed for fish only tanks so they are very low intensity.

If you can find one made powerful enough for reefing, or use enough fixtures to get enough power for reefing (As in multiple T5's in one fixture.), it'll work great.

Post any you find!

 

[oreo54]

T5/compact floro with white and blue,

LED w/b spectrum is inherently different than the above.. thus the current "add ons"...

say you need 2x 165w units on a 4ft with 2-3w leds and smaller wattage lights (not led bulbs) will not cut it

More a geometry thing.. Smaller diodes are rarely lensed so the bigger ones have better depth penetration.

The normal next "size down" is usually .5w so "roughly" you need 6 for every one in the bigger ones..

Dimmable LED's:
You can never buy too much light..
You can buy too little..and the geometry thing..
Thus the over wattage...

Depending how deep your tank is small emitters can work fine.. w/ enough of them..

Also if getting a light with a housing that sits on top of the tank can it be lower wattage (are higher wattage lights built with more watts because they hang 8-12 inches above the tank?

See lens thing..Lenses drive the height and higher up more "watts" needed ..sort of...
Want to lower the hanging height?.. pop off the normally 90 degree lenses and run "native" 120..

A sort of "compromise" fixture:
https://www.amazon.com/Green-Element-Aquarium-Light-Fixture/dp/B00AS479EI

This is only 10000k so not really ref specific but your w/b ones are available and in a
"quad" form i.e really just 2 side by side..

Lower efficiency LEd's ect but use-able.. and not "hung' normally, though many will pop the lenses..
Oh here is a 24" example:
https://www.amazon.com/Timer-Aquari...pID=41sZ8gz6XbL&preST=_SY300_QL70_&dpSrc=srch

At that price though.. well 2 hanging boxes are not much different..
They do not work well end to end ( 2 4ft over 8ft tank) though.

 

[Dana Riddle]

It depends upon your definition of 'green.' The aqua LEDs (actually a green-blue with a peak of about 505-515nm) should work well as this is in the sweet spot of absorption by peridinin. I'm not a big fan of high amounts of red - a 'white' LED should produce enough. But it is a matter of personal preference, as I have learned over the years. I've spent hours discussing spectral qualities, and in one case, only to be over-ruled by the inquirer's significant other (she didn't like the way it made the carpet look.)

To qualify my opinion - look at this chart (particularly the green line (rate of photosynthesis, denoted by rETR, or relative electron transport rate on the y-axis) and the orange lines (photo-protection.) The red LED produced the highest rate of photosynthesis, but photoprotection never occurred (meaning photosynthesis and potentially harmful by-products aren't being regulated by this important process. They were when the coral was exposed to other spectra.)Sure, some red light is OK. Just don't over do it. My 2 cents worth.

 

[mark freshwater]

Thanks everyone , very informative.

 

[John3]

I can’t say what red does for growth but I like running it low, around 20-25% and it adds a little different “pop” to the corals. I don’t have any algae issues and my coral growth is great. I’m running a radion G4.