Struggle with new plant. Browning of leave edges....

Been having trouble with my newly sprouted plant. Have never ran into this issue before. If you look closely at the pic the bottom right leaf is browned and half of it is missing and mid right tip starting. If you look even closer you can see 3 nodes on the stem that this has happened to. It browns slightly from the end up and eventually consumes the whole leaf. This sprout is approx. 5 weeks old. As you can see it is not growing very fast and as it does i lose each new leaf set. Any ideas?

Was running at 24/0 just switched to 20/4 hoping maybe the rest will help.

Sorry, I know i am new and most are reluctant to reply. I have been an observer of the site for some time and finally joined. Thank you all for your time.