Hydro - brown spots and dry leaves

[robincog]

White Widow x Big Bud seeds
Indoor growing tent 48"x24"x60"
Hydroponic
Rockwool surrounded by hydrotron
Hydro bubbler system, 8 gallon tote with 5 gallons of water, leaving about an inch of exposed roots from bottom of 3" pots
Tap water source
Source water pH - 6.9 (treated down to 6.2, I just dropped to 5.6 tonight)
Source water EC - 110ppm (I don't have a EC meter)
5 weeks old
Using complete FoxFarms system and schedule
Currently in week five my ppm is target for 1100-1260 - it is currently 1275
Lighting source and distance from plant - CFLs six 5000k total of 8100 lumens + supplemental 225 LED lammp in the back; has been right at the top of the plants but I just moved up to 4" above; started with three CFLs doing 3300 lumens
Air temperature - at plant level I try to keep it between 68-75
Reservoir temperature - 65
Air % Relative humidity - 35%
Lighting schedule - 18/6
Type of ventilation your room has - so far single fan sucking fresh air into tent
Did you pre-soak your media in pH corrected solution? Yes

Sorry for my first post to be a cry for help but I am loser n00b first-time grower and my girls are not getting any better. Please see pics. Since the girls were a few weeks old the lower leaves have been turning yellow/brown on the tips and spots, eventually covering the entire ends as the leaves dry up and curl. The bigger the fan leaf, the quicker the problem shows up

Massive amount of online research has led to more conflicting advice than I can work-out. The plants have been flushed twice so far and while it helps their growth, it does not cure the problem. They love Grow Big and Tiger Bloosm and can grow over an inch in a day after adding food.

The first three weeks I was accidentally using Grow Big for soil and wondered if that was the problem and I switched to Hydro Grow Big - no change. I have read several places that it does not matter, but have stuck with the hydro nutes.

I read to cut off bad leaves to help prevent them from sucking away good nutes, but now I am worried as the bigger plant is so thin at the bottom. One plant is 18" tall, thin with ok roots. The other is 13" tall, stunted, fuller and with great looking roots.

I have tried more nutes, less nutes and everything else I have read about - so much conflicting advice - too much nutes, too little ... ugh

Pics are of my set-up, a close-up of leaf problem, close-up of tall plant's lower section, and the pile of leaves I have clipped off over the weeks. I don't want to cut anymore big fan leaves! Thanks for any suggestions!

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[robincog]

My choice tonight was to see if it might be nutrient burn and/or potassium deficiency ... so I flush a gallon of clean water and then added a touch of Grow Big and Tiger Bloom which dropped the ppm down to 1050.

[bridge4]

I had the same look to my leaves and researched it. Came up with leaf rust which led to my spraying under my green light with
Rosenthal's Herbicide. Problem went away. That was my experience. Good luck.

[robincog]

Herbicide :) Not sure that would help. Thanks for the tip, I looked up Rothenthals fungicide and liked their approach so I ordered some. It does not look like a fungus though but it does not sound like it would hurt to spray some on the leaves to be sure.

[seldomBLUE]

over-powered nute causing an Mg deficiency. Drop your ppm between 500 - 700. I run my neut based on ppm. I let your tap water sit for a few days. Cal-Mag your source water to about 250 ppm, fert that mix to around 600 ppm. pH adjuster will raise you ppm but still shouldn't be above 800. Now just sit back and wait on new growth.

[robincog]

Late reply but for future googler's - it was nute burn. I went to half of Fox Farm's feed schedule and kept the nutes less than 3/4 of total with my ph adjusters and 110 ppm tap water. The grow came out great and ended up with just over an ounce from these two plants 8 weeks later.

[robincog]

a couple samples of the results284685284686