1st time Organics, Diferent strains, Searching for Mother plants

Hey guys, i have been reading on this forum for quite some time.. this is my 3rd Grow, and its my first time posting.. the first 2 grows were Dwc and i liked it but now i am trying organics/dirt for the first time.

I am allready in week 4 of the grow and decided to post it here so i can keep a log of my grow and get help and advice..

I spent almost all my budget on seeds, i just wanted to try them all hahaha and im looking to find a mother of wich one of those strains i bought

They are:

-Elemental Seeds Mango Tango
-Delicious Seeds Cotton Candy
-Bodhi Seeds Lavender Aura
-Brothers Grimm Cinderella 99
-Dank Genetics Sour Lemonaid

I planted them in a “locally bought dirt/Organic Compost/Perlite” mix

I have a 2,4mX1,5m grow tent and i am using a 600watt Hps for veg

I am also using a Reverse Osmosis filter and doing compost teas

The very first time i fed them i made a mistake and put PHDOWN in the water and PH was 5... right after 2 days i started seeing yellow leaves with brown spots...

After that i have been feeding kelp only mixed in water and dont even change the PH ( I still have not figured this PH thing out with organic growing)

Today I fed them my first compost tea and it was made of:

1Cup Bat Guano NPK 7-3-1
1Cup Kelp meal
2cups Worm castings
1 tbsp Sugar ( i didnt have molasses)


The plants are showing healthy new growth but on the bottom i am having some problems that i cant figure out..

Here are some pictures: