Why dont use actinics in the planted tank?



This is a very controversial discussion. I have friends that actinics really helps their plants, but in all forums says: NO ACTINICS FOR PLANTED TANK. Yeah I want a scientifically response why because, this, this and this. I know about lumens, watts, spectrum, wavelenghts, etc... So if can include this terms I will aprecciate it.


Plant Guru Team
Lifetime Member
Sep 23, 2007
South Florida
Hi Brian.

For myself, it is simple aesthetics and need. I just don't care for the blue tint and my plants do well without them so far....

I know you are looking for scientific reasons, but to my mind, no need to get more complex than that :)

I look forward to the forthcoming reasoned and learned discussion...


thats can be a point, I really have a 9350K tube that tint the water also but I also use red and white tubes that make white light overall. So it can be solutioned. Still what make this ilumination a bad choise for plants.

Tom Barr

Staff member
Jan 23, 2005
I do not think they are bad, but most plants use more in the yellow and red, with as spike of blue.
They look very unnatural and tacky looking from most people' opinions.

A mix is better.

I use 8800K mostly(sorta like the ADA bulbs color temps), or the giesemann powerchromes, maybe 3 daylights and one aqua flora.

I chose mostly on my own asethetics rather than getting a little bit more PUR/PAR out of any one color temp. I honestly do not think it's worth debating since no aquarist can/are willing to measure the PUR differences between atinics and daylights.
So unless they do that, they really can just parrot what has been said by some theory, rather than test.

Practical matters: folks use them in tanks, the plants do not die, look weird colors, but the plants still grow.
Cool white's also work, as do 4000K and lower.........and perhaps better, so why not use those since the coloration is of no concern and they are much cheaper?
I have to wonder sometimes.

I guess aesthetics are not much concern?
They are for me.

So I use more natural appearing bulbs, or if I want to accent red like yourself, use a 9325 with some other more daylight colors to balance it.
I suppose a blue with some red/warmer colors is fine, as long as the total effect looks good to you.

PAR is PAR for the most part.
Beyond that, you need to do the growth studies to demonstrate that one light produces better growth/more biomass per unit time for PUR at the whole plant level.
No one has done that except in a very few rare cases and not for aquatics or aquarium specific bulbs.

Tom Barr


Lifetime Charter Member
Lifetime Member
Jan 15, 2009
I'd have to say appearance as well. Most of the reefers seem to do it as they think the corals look better under certain lights. Of course, this is probably the same group that adds UV LEDs and such to their lighting to get the colors to really pop.

In most cases I read that the new lighting made all the difference and that such and such a light was causing problems or not bright enough. In many cases the light that wasn't bright enough was pumping out so much PAR the corals were bleaching out. Most of it so subjective that any change must be better than what they had before.

Most of the time we have so much excess light that it really doesn't matter what spectrum is more efficient. You're already pumping out so much of one spectrum or another it just doesn't matter. Much like EI dosing. Once you're out of the really limiting areas it just does not matter for any practical purposes other than academic curiosity or for pummeling other people of forums with. :)

That said, I don't like actinics in general and think plants just look wierd when lit with blue light.


Brian20;47435 said:
Im convinced. :D


Prolific Poster
Oct 12, 2008
A couple of years ago, some Chinese scientists have had an experiment on anthocyanin's reaction to different light. Their paper said that anthocyanin was generating most fast (in a culture) when exposed to the light of 420nm. The anthocyanin did not generate at all at the red light.