Help sick plant autoflower JH

[Buckethat]

Hello! Two of my jack herer autoflowers who are at theese photos taken 15 days young from bursting, i am beginning two get theese spots/grey areas/dried out leaves, and one of my plants is looking much healthier then the other one and does not have nearly as much spots as the second one, is this an ph issue? My ph meter has been broke and i have been using 1 drop max 2 of ph down Gold labels, my tap water has been at 8 but when springwater suddenly came it dropped a bit i noticed just recently, or is this something else? Posting 2 pictures, First time grower both in canna coco coir and have not been using any hard nutes only small doses of calmag and Ph’d water that for 2-3 feedings i had to guess the ph

[Buckethat]

[Gjourney101]

You need to invest in another pH mater. I add 1-3 mL of pH down to my gallon of water. PH will naturally raise over time so before anything get another meter and check there first.

[Gjourney101]

Things to do!

-Buy a pH meter if possible (you can use the baking soda/Vinager homemade test kit in a pinch)
-Make sure you aren't over or under watering
-Keep lighting schedules constant.

[Tersky]

First, feed them. They need nutes as coco has none. After the first set of true leaves appear start feeding. Second, did you buffer the coco first? Third, your medium looks awful wet. I would let it dry out completely before watering again. And lastly but certainly not least, get a new ph meter. Ph is vital for coco grows.