Light burn?

[Fordprefect42]

Looking for a take on these. it’s an orange punch x mimosa.

This plant is 5 weeks into flower and theee mottled leaves have been spreading. This is hydro with temps sitting at 75 and RH at 55. PH is in range oscillating around 6. EC roughly 1.2 which seems to be balanced meaning I don’t see significant changes day to day. Running the GH trio with a little TPS calmag. Plenty of air circulation with a tower fan and 2 tornado fans.

LED lights with the hottest spot on the canopy running 50k lux.

I assumed this was either calcium or light burn leaning towards light burn. I’ve raised the lights to bring the max lux down to about 40k, and added a bit of calmag. The only thing that has me wondering is there are some well shaded leaves seeing the start of some similar symptoms which is surprising if it’s light. Also noteworthy is the other plant sharing this res has no issues with a similar light and nutrient profile.

I’m not really worried here. It’s not bad enough or widespread enough to threaten the harvest at this point, but I seem to have this issue with whatever plant I put in that spot. I think it’s 3 grows in a row where my front right plant out of 4 has these symptoms. It’s a weird coincidence it’s always the same place.

 

[farmerfischer]

Thats not light burn.. looks like a calcium issue.. can you post pics of the whole over all plant..?

 

[Fordprefect42]

Thats not light burn.. looks like a calcium issue.. can you post pics of the whole over all plant..?

That was my first thought although the burnt curled tips had me thinking light until I saw shaded leaves starting to show similar behavior.

larger pic attached. This isn’t a real threat to the plant, but it can’t be helping.

 

[farmerfischer]

So are you giving cal/mag with every feeding? Are you in pro mix or coco? Tap water or R.O. water?

 

[Fordprefect42]

So are you giving cal/mag with every feeding? Are you in pro mix or coco? Tap water or R.O. water?

so it’s ebb and flow using half and half ro and tap water with hydroton. Our tap water is pretty hard so the half and half reduces the base tds to something manageable like 110 tds. I’ve been typically adding 1ml calmag per res top up which has been about a gallon a day lately. I changed out the res entirely a week or so ago to reset things. I was not using calmag until I started seeing issues.

In my head I had arguments for either light burn or calcium, and figuring it didn’t hurt I started explicitly adding calmag at top off.

 

[farmerfischer]

Maybe ditch the flora gro and just use the flora micro and bloom. Ive found that the trio is abit high on the nitrogen.. ive use the trio for years on flood and drain (hydroton) and drain to waste with promix.. and maybe stop adding cal/mag.. and see if this helps.. it looks like a cal and phosphorus/potasium problem.. but its probably not a cal/mag issue at all..

 

[Fordprefect42]

Thanks for the thought. The calmag has worried me a little since it antagonizes potassium. I actually did that my last grow since micro has some nitrogen. I started reducing the green stuff eventually hitting zero but grow does have a lot of potassium so you lose some of that with it.