I used HPS before then switched to Mars leds. Lighting performance is amazing. I think more CAL, MAG will be needed under led and less water and nutrient under led.
Sorry, mate! But the later is nonsense!
Plants under intense LED light will actuall need more nutes. With a 600w HPS you get ~500 - 600μMol/s/m² depemnding where you measure, with "good" LED 30w/sft is already above that and delivers at least 800μMol/s/m². With 40w/sft it's already up to 1000!
When humidity and temps are in a good range (according to the VPD charts) plants use more water AND more nutes!
Only when the VPD is too high you need to lower the nutrient strength accordingly. Lets say you normally use 1000ppm at 30°C/65% RH and your humidity drops to only 55% for some reason. What will happen?
Because of the higher VPD plants take up 10-15% more water and therefor also take up more nutes!
So to avoid problems with over-fertilization the nutrient strength should be reduced by about 10-15%. The plants can take up and transpire more water but still get a healthy dose of nutriens.
The reason why you experienced less nute consumption is not because of LED light; it's because your Mars lights are rather weak and the intensity is probably not even 500μmol/s/m². Logically, that you needed less nutes with such low intensity.
Can I ask which Mars light it is and how big your area is?
That's what a well known member of this forum has done with his mars lights as he realized that Mars lights are of lower efficiency than hps. And this was already a few years ago when white quality COB's reached ~2,0μMol/J. Now we are in the range around 2,5μMol/J and the best available Mars light currently(1 Cree COB and a few XPE's) has just below 2,0μMol/J.
...but at least the case quality and resilience is amazing, lol!