Usually when I do it if the seed hasn't broke through soil after three days, I remove the cover and it never fails the next day will sprout!! So you can remove now ... Personal preference!
It looks like you burned the plants ! I have my first grow going now and into flowering now about two weeks in! I never check ph and only had that problem once with too much nutes! Check mine out Pineapple express and Mekong high!!
I topped my Mekong high using the FIM method and now have like 4 colas forming.... Just started to see the buds forming on mine it's awesome!! The plants are leaning towards the light looks like u need more light!!! Also chill on the nutes ur killing it lol!!!