Is this phosphorus or magnesim deficinecy or nute burn?

[curryguy3]

2/8 plant have this problem. Temperature has been bit high (80f). I use GHE flora with Lucas formula + calmag + bloombooster. Its 5th week of flowering.

PH has been mostly between 5.7 - 6,2.
The EC started to rise quite fast 1.5 -> 1.79 (in one night). So I did change the res, flush yesterday.
After that the EC dropped from 1.29 -> 1.19 during last night.

Please help I am affraid I lose the plants ?

Tent: Gorilla Shorty 4’x4’
Lights: Mars Hydro TSL 2000 (2x300w)
Exhaust ventilation: UFO THERMO (400 m3/h / 235 cfm)
Fresh air: VENTS QUIETLINE (200 m3/h / 117 cfm)
Carbon Filter: PRIMA KLIMA (480 m3 / 282 cfm)
Air movement: 2x 15cm/6" Fans
Hydrosystem: Atami Wilma 8 drip irrigation with hydroton

 

[Jayded]

How close do you have the lights?Could be leaf burn from them getting too much light.

 

[curryguy3]

How close do you have the lights?Could be leaf burn from them getting too much light.

The light was in 14" but I raised to 18" (972 umols). Do you think that is sufficient or should I raise more?

 

[Jayded]

I usually hang mine at 20/22"above tops,any closer will cause burn issues on some plants,not all though.

 

[curryguy3]

I usually hang mine at 20/22"above tops,any closer will cause burn issues on some plants,not all though.

What lights do you have?

I have 2x Mars Hydro TSL 2000 (300w each).

 

[xxPeacePipexx]

Your roots hold the answer! It's not a deficiency or light burn, it's pH/EC related.

 

[curryguy3]

You right it might be, my PH dropped under 5.5 for a while. Which cuts out both phosphorus & Mg

 

[RockinRobot]

As a general rule, Unless you're mixing your own nutrients from scratch, Deficiencies are almost always caused by Ph issues. Commercial ferts today have everything the plant neds

 

[curryguy3]

Thank you guys!