I think switching from T5 to LED and the experience you get and perception is very much down to what you buy in terms of LED. There are numerous units on the market all stating "full spectrum" "high intensity" etc etc, but thats not the important part, instead how the lamp delivers that light is.
Majority of people will look for the "affordable" option or feel a cheap lamp is as good as an expensive unit because it lights the tank right? This here is the make or break in many cases where the lamp will make you feel the switch was a success.
Ok lets break that down further and much of it comes down to the tools used to deliver that light to your corals.
Doing enough research you will see many LED companies are using the same diodes now. That does not make them all the same. Forgive me for using the highest end LED on the market as an example but it is important to see how people who buy cheap units or less equipped lights can get a bad experience where as those that opt for the full bells and whistles will sing from the roof tops how LED has transformed their system in the long run saving them money as not feeling LED was not for them.
Any LED (as proved by DIY) can illuminate your tank, however multiple diodes shining down on your tank in different colour patterns does not create a spectrum corals are used to. For example a T5 bulb creates a combined light output of varying colours to create the spectrum it delivers, so a GOOD LED unit should do the same.
As an example GHL Mitras uses a unique reflector system that took 2 years in development. The biggest wow factor of the light is that the individual LED's are allowed through refraction to converge, the reflector allows for over 98% of refractive light back to the tank. This is the key point here, you get what you pay for, system like this cost money to develop. Developing such a reflector as the Mitras uses has enabled the lamp to compete with T5, probably the first LED light to be able to do this.
Points of failure for an LED unit are
Hot spots, where the lamp directs beams of light to small areas of the tank, yes this creates huge PAR values but also risks burning the coral at worst, stress at best
Disco ball, This is seen in so many lamps, look at the bottom of the tank and you will see colour separation of the LEDS, they have not converged, this is not how T5 work or look so how can this be of benefit.
Dimming?
One of the biggest draws to LED is the programmable benefits for dimming, however it needs to be deployed correctly. LED lamps are driven by a digital signal for control. Most here I think will understand the digital workings = 010101 binary code = 0-5v or similar control line voltage. there is no in between it is either one or the other.
When an LED dims it does so by a signal line voltage change (a step up or step down) if you look at an LED unit especially at low level of light you will noticeably see the light dim from one set point to the next, set a dimming pattern of 5 minutes from 20% to 0% and just watch it.
How to address this?
Going back to high end units and getting what you pay for . For example the GHL Mitras using a technology (pattented) called LDT "Linear Dimming Technology" what this does is turn the digital output signal into a linear analogue signal with over 4,000 dimming set points between each step, this is way and beyond anything the human eye can see, so when you want rolling clouds across your tank you dont want to see a choppy dimming curve you want a smooth curve, only generated in LED units by changing the output signal to linear analogue.
So in conclusion, to get a real T5 vs LED experience you do need to look a lot closer than just PAR output and price. The lamp has to have the inbuilt technology to compete against T5 in terms of convergence of output of the LEDS at least. We all spend a lot on our tanks and how many times do we buy something and then wish we bought that other one, whether it be food supplement or equipment. Look at the whole package being offered, look at the long term aims of what you want to achieve and look at longevity, its a waste of money buying something cheaper only to throw it away 18 months later.
Ask the manufacturer -
Does your lamp converge all LED's without any disco ball effect? will they guarantee it? return
Genuine indpendant proven spread? will I need more of your lower cost lamps than I would of a more expensive. (often making the more expensive cheaper)
Does the lamp employ LDT? Will I see steps in dimming?
Warranty? should be 2 years in my view.
So is LED worth the switch?
YES - If you buy the right lamp and invest short term in something that delivers what a T5 delivers. If you cut corners then there is a good chance you will regret switching.
Good luck with everyones choices and I hope this insight is of some benefit to the community.
