if it is bleached what can i do to help it return to normal?
The 0 nitrate is an issue. Nems need some available. If this was tested using API, you may have some nitrate there, but if using Salifert, Red Sea etc and it is 0, then that is a big issue.
As for the stock light on the 13.5 I am not sure on if it is enough for a nem. It may be up high, but if the nem has no nutrients available, then it will not move up, as any light is harmful to it at that point.
In addition, with the tank being so new, the nem may be experiencing additional stress due to parameter fluctuations associated with it being a new tank.
With that said, you need to bring up nutrients a little. I aim for 2-5 NO3 and .03-.1 for PO4.
If it was me, I would get those nutrients up some and within a week or 2, you should see the nem start to regain color, provided the stock light is enough light. This may mean the nem moves up on the rocks as well, once the zoo in it has something to eat.
Also, you are going to hear "your tank is too new", "tank is not old enough", etc. While this is partially true, if you are willing to put the time and effort into the tank/nem and keeping things stable, then you can make it work. If you do not want to put thatmuch effort into the nem, then I suggest rehoming it. This is of course up to you and for you to decide. I just want you to be aware that while not recommended, it can be done.
Edit: Forgot to comment on the too small of a tank. I have kept nems in 2.5 gallon tanks. 13.5 is not too small, as long as you can keep thing stable and provide what the nem needs to thrive. This does not mean everyone can keep a nem in a 2.5, I am just pointing out that it is possible with enough work.