Is this light burn?

[pegz]

These 2 plants were about 12 inches away from the bottom part of a large reflector w/600W MH. The heat coming off the inner sides of the reflector under which the plants were sitting is fairly intense, I'd say hot enough to dry out a piece of bread in a couple of minute but not hot enough to start turning it brown. The affected leaves feel quite brittle, but I can still bend them without breaking them apart.

 

Ambient temps are around 25.5 - 27.5, humidity is around 30%.

 

I also fed these plants a couple of days ago, so there is the possiblity its nut burn or maybe even pH flux as the pH was a tad lower than usual.

 

Thanks.

[buzzo]

You have temps under control cause there is no signs of Leaf Curl.

But yes you are a little close to the light, should be 10 inches or more from the light source not the reflector

 

This is a pretty good chart you can go by

I find it's about 2 out with the 250 Watt I am using.

I don't let them get any closer than 10 inches with the 250 watt but chart says ideal is 8 inches.

 

They really don't require bucket loads of light before they flower

 

[pegz]

There is actually quite a bit of leaf curl, not so visible in those pics.

 

I'm thinking that it might be the pH, they went from 5.9-6.0 to 5.5, which I didn't think would shock them too badly but yeah, I dunno. If it gets worse overnight I'll flush em tomorrow.

[oldfark]

General rule of thumb for 600 w lamp introducing immature plants 600 mm from lamp to start and gradually move closer over a period of a few days.

For 400w 400mm and so fourth. Easy to remember.

300mm is way close.

peace and love.

Edited August 8, 2013 by oldfark

[buzzo]

There is actually quite a bit of leaf curl, not so visible in those pics.

 

I'm thinking that it might be the pH, they went from 5.9-6.0 to 5.5, which I didn't think would shock them too badly but yeah, I dunno. If it gets worse overnight I'll flush em tomorrow.

 

5.5 is still in the Tolerable range, so I doubt it has caused any problems.

[pegz]

It was getting worse so I flushed em late last night:

 

 

Note that some of the leaves are showing what looks most like a K deficiency, also note the bottom leaves are unaffected.

 

I repotted these plants 4 or 5 days ago with some older coco brick mix without first checking its pH, if it was high like 6.5-7.0 it might explain the trouble I'm having after feeding the plants with a 5.5 solution.

 

Here's another plant which isn't showing burning but is showing some curl, perhaps I have heat stress problems as well as a pH or nut problem? (This plant got different coco than those other 2 when I repotted them all.)

 

 

Anyways I've flushed em with pH 6.0 tap water, I'll know in the next few days if that was the problem.

 

-

 

Thx for the help guys.

 

[pegz]

Well it was remedied with a flush, it was either the pH or too much nutrients, probably the latter. I've turned down the light to 75% (450W) and things are more manageable, temps down to mid-low 20's + rH up to around 40%, nice a stress free.

[buzzo]

If you use brick Coco you need to flush the living fuck out of it before you use it.

 

Lou uses that nasty shit and has no problems.

 

Good to see things are back on track. What E.C. level are you running.

About 1.6 should be fine..

[pegz]

It was only 1.1 but I jumped from 0.6 the previous feed, so I guess it could of shocked them? I did see quite a growth spurt but also burn, but yeah I need to start upping the nutrients now, just more gradually I guess. Plants are 5-6 weeks old now, but some are lagging due to a bad start.