I was thinking about LED lighting but haven't a clue where to start. Does the wattage/litre still apply or are led's different. I'm happy to have I medium light amount so minimal co2 but want the plants to thrive. I've seen some on Amazon but wouldn't know which ones are any good and the ones at the aquatics shop are a stupid price.
It's the same but way different....
watts/gallons or lumens/liter hold SOME validity still. Physics hasn't progressed that much.
Generally LED efficiency (photons/watt) is equal to (or better, sometimes much better but lets leave that out for a bit) a t5 or t8 (8's and 5's have similar watt efficiency, only one uses more watts).
Now the tricky part is LED's are better at directing those photons so in effect they are higher in overall efficiency.
The plus (big plus) is they are easy to dim so going overboard isn't an issue like using 4 tubes and only really being able to handle 3 tubes so now you need to dim, somehow.
So picking led's on the same watt/gallon basis usually works out in your favor.
Of course there is more to it than merely numbers of photons. Tank needs to look good as well which is a whole new story.
Your 60w on about 60gal works fine. 60w of "good" leds should be stronger. In reality sometimes 2x stronger at best, generally 1.5-1.25 is a fair estimate.
If all you see w/ leds is lumens..go about 4000+. your t8's are about 5400 lumens for parity.
Keep in mind some cheap leds may not equal t8 efficiency but even the worst shoudn't be lower than about 3/4's. Some old 3w diodes may still be around 60l/watt where tubes are about 90l/w
You make up for the losses w/ better delivery.
Point is going 1:1 watt/watt should be "safe" if not better than what you have.
PAR measurements are best but one needs to start somewhere.
lighting guide
corrections: GE lists 30w t8's at 1850 lumens each so 2 = 3700 lumens. So adjust accordingly. Sorry, don't want to re-write the whole answer.
But to answer your question better,an led of 3700 lumens or better will push up your light output.
80 to 100 lumens
Today it is commonplace to find T8 fixtures producing on the order of 80 to 100 lumens per watt of output, putting fluorescent lighting at the top of the efficient lighting ratings in terms of lumen per watt efficiency.Nov 15, 2013
Best leds are approaching 200L/w but most average around that 90-100L/W. But remember at 120 degrees (common) targeting is increased.
LED strength and weakness (more shadowing not as diffused as tubes)