Do you have a strong magnifying glass…say 100x or so ?
A friends strong glasses prescription…lol
Anything that will zoom up your view to see if there is any pests…most are very small and hard to see with human eye.
As far as nutrients…do you have any test pens for pH and ppm/ec reading ?
You may want to start checking your water going in and coming out before you add anything more that could end up harming them more. Cheap testing pens (like mine) go for about $20 or less and are a need for new growers like us to get things dialed in correctly.
The plants look normal really…the slight dead edges can be from the leaves touching the soil when its wet…aka “burn”…and the soil may have some nutrients/fertilizer in it. What brand/type of soil did you use ?
In the 3rd picture…not sure what the white color is down center of the leaf is…do you spray plants with water?
I would monitor the plants for a few more days to see if problems continue to go up the plant and effect more leaves or not…taking lots pictures helps you look back and compare.
As far a killing possible bugs you could give it a spray of 3% peroxide and water (mixed 1:9 parts) or iso alcohol instead of peroxide…spray when sun is down (or lights out if indoors) due to the sun can make water droplets turn into magnifying glasses and burn tiny holes or badly mark up leaves.
A lot of the questions I asked are in that support ticket…so quicker its done the quicker I believe others will join in helping out too…just so many possibilities to say for sure, but no worries your doing ok and the plants look very healthy still…good work thus far…keep up the good work. 
PS Heres a good read @Jbum did up to help identify problems… Deficiencies with pics, descriptions and remedies