Looks to me like leaf-tip irritation. Happens when one leaf get's blown back-back-n-forth across nearby leaves, resulting in those little brownish spots. With the circulation fans pushing leaves back-n-forth, I've even see irritation spots that look like long, narrow bug tracks. Does look in the third pix (leaf with speclkes) like you sprayed with nutrients or ammendments without raising lights, but that too might be a leaf irritation situation. Sometimes the leaves get blown up-n-down instead of back-n-forth. No big deal. :jointsmile:

Everything else looks pretty good. Eventually, with the filtered water you'll want to add some source of calcium. I recommend unsulphured molasses.
Also, next transplant you'll likely want a lighter soil. Preferably potting soil with perlite. While you are out getting that...some more light wouldn't hurt at all.