i read in hydro that a mistake can happen faster then if in soil but can be rectified quicker too. Number one PH needs to be right 6.5 there about. Every point higher you go on your PH ='s times 10 to your plant. Brown spots are her way of telling you she has a nute lock out or deficiency. Flush them with 3 times the amount of water you normally use. Better have the Ph right and then feed them b-1 to help recover for shock then when you feed them again do it half strength and work your way up. Like 500 ppm to 850ppm
wait 24 hour and see if they are lacking if the ph is right the nutes are available if they are in there?
might want to copy and paste this into a notepad in your RIU.
Quick Deficiency Guide
Nitrogen: Entire plant is light green in color; lower leaves
are yellow; growth is stunted....
Phosphorous: Entire plant is bluish-green, often developing
a red or purpleish cast; lower leaves may be yellow, drying
to a greenish-brown to black color; growth may be stunted...
Potassium: Leaves have a papery appearance; dead areas along
the edges of leaves; growth is stunted...
Magnesium: Lower leaves turn yellow along the tips and
margin and between the veins; the lower leaves wilt...
Calcium: Young stems and new leaves die...
Zinc: Leaf tissue between the veins is lighter in color;
yellowed; papery in appearance...
Iron: Leaf tissue appears yellow, while the veins remain
green...
Copper: Leaf edges appear dark green or blue; leaf edges
curl upward; young leaves permanently wilt...
Sulfur: Young leaves turn pale green, while the older leaves
remain green; plant is stunted and spindly...
Mananese: Growth is stunted; lower leaves have a checkered
pattern of yellow and green...
Molybdenum: Leaves are stunted, pale green, and malformed...
Boron: Young leaves are scorched at tips and margins...