Plant refuses to eat!

[Icefisher]

Hello, I hate to continue to beat this horse, but, one of my two DWC plants continues to struggle and I need some help to figure out what to do with it. Based on the measurements of ph,ppm and EC the plant is taking up very little nutrients. For about 3 days now there has been no change in the ppm and correlating EC measurements. I am maintaining the ph at about 6.0 and the ppm at 1240 using a combination of Master blend, Calcium nitrate, and Epsom salt. The root structure looks healthy, strong and white. The light intensity is at 40 watts per square foot being lit by a HPS 1000 watt bulb. Lights are on for about 15 hours a day. Sporadic leaves and then branches are dying from the outer leaf tips. The plant is producing flowers (see photo), but, considering how the branches are drying and then dying, I don't understand how this can be happening? The other plant is doing exceptionally well and has been setting fruit. I am at a complete loss at what else I can do to revive the vitality of this plant. The first photo is the sick plant. The other photos are of the dying and drying leaves and branches from this plant.

Thanks
Icefisher

[KarenO]

Leaf tip burn is generally a sign of over, not under fertilization.
https://www.hydroponics.net/learn/de..._element.asp#B

Look at toxicity symptoms for sulphur, boron? I am not a hydroponic grower but Too much of a good thing can be just as bad as not enough perhaps. Epsom salts has a lot of sulphur for example.

KarenO

[Stvrob]

What is the electrical conductivity?

[Icefisher]

The EC is 2.00