I think i got a Potassium deficiency?

Im running a DWC set up I but together and im using the whole technaflora product line and following their recipe for success. Now, all my seedlings are a week old their from tiki seed bank their mix pack and the thing is that im only having problems with the 3 in the front of the set up, I got 40w tubes over them ajnd a cfl on the side the temp never passes 80f so I dont think their getting heat stress I looked at the FAQ and thought it looked like they needed potassium I've been spraying all plants with the root 66 and sugar daddy 1/2 strength to help with root growth like instructed in the chart also the chart says to use 6.8 ph for their recipe and that if the ph is not that way to adjust it which threw me off alittle from what Ive been hearing of using 5.5 I wish my pictures were better but thats the best my cheap camera can do. basically the tips and the sides are curling up and theirs a little yellow coming in one is worst then the other 2 any help would be great thanx

I dont know what it was but this morning their looking better new leaves coming in and look nice and green

That one pic look like it's got some nute burn going on there....

yeah i flushed them and know their doing better ima get a better camera and then post pictures of the growth later thanx

Now they are bigger and growing i had to change rubbermaide tote to a stronger one and i stoped using vinegar as a ph down dont do it in a couplke days im doing full strenght nutes and ima watch em explode