How much light is too much light?

[AllSignsPointToFish]

I currently have three Kessil A360WEs on my 125 gallon tank. If each Kessil is roughly equivalent to a 400W metal halide lamp, that would seem to be enough light.

However, I've heard that people have had good luck supplementing the LED lighting with T5HOs. As such, I've been toying with the idea of adding two 80W T5s to the mix at some point. I also ran across a 4-bulb T5 fixture on Amazon for a pretty decent price. How much light is too much light? If I add 320W of T5 to the 270W of Kessil LED lighting, would that be enough light to grow Acropora, Millipora, and such? Would that be too much light? At least with the Kessils, I can always dim the LED fixtures to balance the total light input.

Thoughts?

 

[saltyfilmfolks]

Par meter or lux meter. Read up on dana riddle in advanced aquarist.

 

[hart24601]

How much flow do you have? This gets overlooked too often, excess heat from the light is released as heat. Higher flow allows for more light before bleaching. What coral do you have in there now? If lps or softies do you see them start to shrink as the day goes on? That generally means your at their light limit if you see that.