Brown/Rust Colored spots on plant

[Loblolly1]

Hello, these are some pictures of some white rhino that has recently shown some problems. Over the last couple days, this rust-colored spots has been moving up the plant sort of eating away at it.

The plant is in Fox Farm Ocean Forest, and has been fed Earth Juice Grow 2-3 times over its lifespan. It's under a 400W HPS light with other plants that aren't showing such issues. Can anyone help tell me what they think this is?

 

[MynameStitch]

Plants are hungry, I see magneisum deficiency, possible either phosphorus or calcium.

You using Ro water?
tap?

You need to start feeding your plants weekly, they used up all nutrients in there medium.

Use around 1 1/2 teaspoon of grow every 7 days.

You also need some micros, get some earthjuice microblast or get some cal mag for some micros.

 

[Loblolly1]

I'm using tap water, and I just tested the pH - it's coming out of the tap at about 8.2

 

[MynameStitch]

have you tested it after it comes out of the bottom of the pots?

 

[DIGITALHIPPY]

looks like calcium def, probably the hard tap water wierd coloring, wanted to say mag issues, but could be nitrogen lack, tap water is junk in most areas, how many ppm's is the tap do you know?

 

[larry badiner]

check your soil ph, i started noticing deficiencies in my plant and it was because my ph level was below 4

 

[Lt. Go0B3r]

i agree with digitalhippi...most likely a calcium def.