Spacebucket SLH auto Yellow/Dry leaf

[XHausteD]

Hey guys,
My girl is An auto SLH in a 100L spacebucket
I use 250w full spectrum cob led 5x50w
I have 1 usb fan and 2 pc fans for inline and exhaust
Temperature is 24-25 and humidity is %50-60
It is 28th day today and my girls leafs are yellow and dry this is my first grow and i dont want to fail here is some pictures. What is her disease and what is the cure.
thank you for your support and help.
And I use AN Grow-Micro-Bloom set

First time grower waiting for all responses

 

[namvet25]

Is this happening on lots of leaves or just a few bottom ones?

 

[Rev. Green Genes]

calmag for the COB's, but as Namvet says, if it's a few it's needing calmag, if it's everywhere your looking at pH fluctuation cal lock.

 

[XHausteD]

New leaves are okey and looks good but bottom leaves are getting worse everyday. How should I use cal mag for my plant?

 

[Waira]

- we need info on your feed inputs, how much, how often, EC/ppm's, pH and if it's been stable,... it looks like a touch of nute burn maybe, but those symptoms are kinda generic, could be a few things,...