Anyone here went from hps to mars hydro?

It only depends on if you have to run a heater or not. Plants metabolism seems different under led. And it would make sense as some elements - like Ca, which is often involved in issues under leds - are transported via transpiration. So to offer the optimal conditions, one would want slightly higher temps than with hps. And that's the big issue with leds. I do love growing with leds and i would never go back to hid. But if you aim for optimal temp and have to run a dedicated heater for the major part of the year, the saving would be much less than expected, especially lately...

efficacy is directly proportional to watts saved -- as long as you are applying same umol/s of photons to the plants -- you may want more than you were giving, if upgrading and not quite reaching max DLI... hps are something like 1,8 umol/J efficacy. wow, says 'new' ts3000 is 2,7 umol/J, which i find a bit hard to believe, but maybe true. it's got bridgelux chips. i'm gonna call bullshit on this one. They tend to fib a bit on the cheaper models. The price is good though. I'd wager it's closer to 2,3 to 2,5 efficacy range. if you want to dig into that, read up on the bridgelux chip and compare to lm301.. i highly doubt running it at nearly ,5 watts per diode is what bridgelux tested those diodes at, unless they are "1w chips." So it'd poduce at least 40% more photons per watt than your 600w HID (,7 / 1,8) based on efficacy difference, give or take. It will last longer (not 50-60k hours if i am right about efficacy fib, above) -- i used 2,5 umol/J for the ts3000. 2,5 - 1,8 = ,7 it would be an improvement. it will reduce heat in garden. it should last at least 4-5 years of heavy use and even longer if not year round use. what you get if you spend a bit more -- better samsung lm301 diodes, little better efficacy - a true 2,8 ish range - which would reduce heat further. longevity will definitely reach 50-60k hours if run at samsung com spec sheet parameters (longevity is usually the point at which it is 90% as bright as day 1 = 50,000 hours or more). You get what is advertised in this regard when the diodes are powered as the original manufacturer tested them. FC4800 (480w) is an option. you may not need to run it at 100%, though. You only need 380-400watts, if you were hitting 'max DLI' with you HID light. (google daily light integral - best apples to apples comparison of how much light you give a garden). You may find you can give more. FC4800 can cover 4x4 area for photoperiods on a 12/12 schedule. for autoflowers, it can cover 150% more on a 18/6 schedule. hours of use are just as important to DLI as power and area of coverage ( 12 -> 18h - 150% more DLI at same power/distance/area, so it can cover 150% more area and still provide same DLI as before with 18 vs 12 hours - proportional). 35-40 DLI is your goal with ambient co2. 50-60dli is goal with 1300ppm co2 and tightly controled temp/rh. you may find you can give more and therfore need more than the direct conversion from your 600w HID to an led equivalent. in that case the FC4800 is clear choice. If running autoflowers, exclusively, FC3000 (300w) is an option in a 4x4 area, and will still do a decent job with 12/12 photoperiods, but better in smaller area. The fc series are a higher quality light. they'll last 7-10 years of heavy use. produce less heat. reach advertised longevity and efficacy.

Just do it it's worth it i used to run HPS for 15 years, LED is definitely better right now i run 2 Mars hydro SP3000 in a 120x60cm tent with a 150mm ventilator and it feels extremely easy to keep the temperature down, HPS is a dinosaur in my eyes i would never go back.

Having run a 600W HPS in the past and now having both a 200W and 300W LED, id never ever go back. They use HALF the power, produce HALF the heat, and you dont need to change globes every year. Each LED is good for around ten years or more. And a 300W LED will produce more bud than a 600W HPS. Facts. Im currently running a 150W VoparSpectre XS1500 on 50% power at 12 inches above my 4 week old plant. Go look at my diary-she is LOVING life so hard I will never go back to HPS. When she is ready to go into flower, I will swap out the 150W and throw in a 300W SpiderFarmer SE3000. -Same as the Mars Ts3000 basically. So yeah, you can run the 300W Mars light on 305- 50% almost up til you switch to flower so you save ALOT of electricity VS the HPS. Basically the only people running HPS should be people who cant afford to buy a LED yet... There is no good reason to run a HPS unless you NEED the heat from it to warm your tent/room. Thats it.

For sure the cost and the outcome will be quite better 1st cost of running will save 30 to 40 quid running at full power on 18hrs and 2nd the outcome in yield will be much greater if you follow the correct distances from the plants otherwise will stunt them very easily try 50 %at minimum 30 inch in veg to see the stretch plus will be goo to stretch the plant at 1st just enough to gain weight and promote the root to propagate before it can stretch a bit more think that they are a intelligent living being give them love only and they just will grow before you eyes...

I was running 2 1000w hps lights and switched to 3 650w HLG650R and would say the running cost was pretty close to the same. As far as Flower production goes, I did notice an incredible difference having doubled and tripled the weights on some strains.