Ed nailed this in the first reply... I am also only into acropora and only apply this to keeping them...
It goes like this...
Step 1: some people believe the crap that shops, stores and shills can really get good results out of LEDs alone for acropora, or that each type of light can do the same thing.
Step 2: after a while, and once they get to a higher level of reefing awareness, they see the issues and add a few T5s
Step 3: the reefer is amazed by the difference a few makes
Step 4: start to wonder what will happen if they add more T5s since people that they never wanted to listen to have always tried to tell them that they were better for acropora... and they saw what only a few did
Step 5: they change the paradigm and start to have the T5 do the heavy lifting and keep around some LEDs to satisfy their hunger for thunderstorms and black light
Step 6: become less dependent on the LEDs at all since now they don't need them to make their corals look good when you "blue it up"... they just look good all the time now that you have better lighting.
I will also totally contend that the oft-mentioned coastal reef shops are only really impressive to those who are in step 1 mentioned above. Each time that I go, I only think: man... this could be so much better. Then, I remember that they are building/running a business and have different goals than us and catering the needs of people in Step 1 is amongst the highest priority for them. Their tanks are middling level for acropora hobbyists, and that is ok... they are not hobbyists.
Seriously, just skip to the end if you want to really work in Acropora, and work well. I would strongly recommend a 48" T5 fixture and then get some LED light bars for each end - that would look better and the ReefBrites (if you can get them in Spain) pop better than Kessils do, IMO.
Been reefing for more than 10 years, always with T5.
But because my tank was a cube, I switched to led, and I don't regret this years.
But have never forgot what T5 are and do. And I don't think led are a bad source of light either. Just than T5 for my setup is for sure better. But got no science to prove it.
Using a 48" T5 fixture would double or more the budget (the 36" is way cheaper due to excepcional causes)
And there would be little space for any additional bar, or similar.
therefor the idea of using the extra space on each side to use kessil. .
The use would be 8hours T5full. 2 hours dimming t5 (1rise and 1 sunrise) and 12 hours kessil with white peak
But maybe is not as good idea as I think.
The kessil thing.
I like kessil on the paper. Blue specter seems to be perfect for the fluorences and bringing up more colors, but seen many people use SB or reefbrite.
For me would difficult to find them, but could find them hopefully.
Is there so much difference?
Thank you all for your replies. You are really helpful
sorry for the quality, quick pic just as is getting dark...(or blue)