Light burn? Mars Hydro 600w series 1 panels

Hey, firstly these plants are not all the same strain, the ones that have suffered the most are sativa dominant and are Orinoco strain, the larger plants are indica dominant hybrids of various strains, they are in a 1.2mx1.2m space under 2 marshydro 600w panels (the ones without IR and UV)
At 24 inches+ there's no problem with yellowing on the leaves but when lowered to the advised 18" above canopy the yellowing starts pretty quickly, does anyone have any similar experience or advise on what the actual cause could be?
The tent doesn't seem hot at all, the panels run pretty cool.

Maybe the light was too close for the age of the plants? I burnt some young plant at 30" with a cheap Chinese light but when the plants got older I was able to get the light back down to 30".

Dsmile said:

Hey, firstly these plants are not all the same strain, the ones that have suffered the most are sativa dominant and are Orinoco strain, the larger plants are indica dominant hybrids of various strains, they are in a 1.2mx1.2m space under 2 marshydro 600w panels (the ones without IR and UV)
At 24 inches+ there's no problem with yellowing on the leaves but when lowered to the advised 18" above canopy the yellowing starts pretty quickly, does anyone have any similar experience or advise on what the actual cause could be?
The tent doesn't seem hot at all, the panels run pretty cool.

Click to expand...

nutrient tip burn ?

hint: photo's too high data rate to view easily

Dsmile said:

Hey, firstly these plants are not all the same strain, the ones that have suffered the most are sativa dominant and are Orinoco strain, the larger plants are indica dominant hybrids of various strains, they are in a 1.2mx1.2m space under 2 marshydro 600w panels (the ones without IR and UV)
At 24 inches+ there's no problem with yellowing on the leaves but when lowered to the advised 18" above canopy the yellowing starts pretty quickly, does anyone have any similar experience or advise on what the actual cause could be?
The tent doesn't seem hot at all, the panels run pretty cool.

Click to expand...

These Mars lights have a strong center hotspot and these plants are too young probably to handle it. They use lenses or reflectors to get high center readings and claim what a powerful light it is. But in fact they boost the center reading to the costs of uniformity. Therefor the plants further away from the center have no problems. Is there a way to remove the lenses? With the 120° beam angle of the naked diodes you would see no such issues. If its impossible go back to 24" and reduce slowly to 18" so the plants have enough time to acclimate to the new conditions. Maybe 2" per week to have them at 18" from bloom week 2...

Thanks for the replies, im convinced it is the lights and not nutrient burn, what Randomblame says about the central intensity seems to ring true as the outer perimeter of the plants look very healthy, i'm planning on switching the light cycle this week as they have been vegging for months

Dave455 said:

nutrient tip burn ?

Click to expand...

Nope, it's pretty obvious bleeching because of a too strong center hotspot. Typ. for the most blurple fixtures using lenses or small reflector cups.

Dsmile said:

Thanks for the replies, im convinced it is the lights and not nutrient burn, what Randomblame says about the central intensity seems to ring true as the outer perimeter of the plants look very healthy, i'm planning on switching the light cycle this week as they have been vegging for months

Click to expand...

Yeah, rise the fixture back to 24" and the damaged plants will probably recover. Put these girls on the sides for at least a week or more untill there is enough healthy new growth.

Randomblame said:

Nope, it's pretty obvious bleeching because of a too strong center hotspot. Typ. for the most blurple fixtures using lenses or small reflector cups.

Click to expand...

Best to spread that light out with COB's or QB's. Those types of LED lights have given all LED's a bad name now. COB's and QB's are not the lights of 10 years ago.

Mars 600 seems like their oldest light. Have you tried their new light?

Dsmile said:

Hey, firstly these plants are not all the same strain, the ones that have suffered the most are sativa dominant and are Orinoco strain, the larger plants are indica dominant hybrids of various strains, they are in a 1.2mx1.2m space under 2 marshydro 600w panels (the ones without IR and UV)
At 24 inches+ there's no problem with yellowing on the leaves but when lowered to the advised 18" above canopy the yellowing starts pretty quickly, does anyone have any similar experience or advise on what the actual cause could be?
The tent doesn't seem hot at all, the panels run pretty cool.

Click to expand...

Try raising the heat a bit, to around 80-84. The plants will drink a bit more and thus have more nutes at their disposal and have less problem using all that light.
Lowering leds: 1 inch at a time to make sure