yeah, those 3 fish will have to go to the bigger tank. The clarkii and angel will become some pretty big mothers.
If you are in the process of setting up the 55, I would look at 75-80lbs of LR. The general rule of thumb is 1-2lbs/gal. I think the rock might have been one of your biggest issues. I also disagree with Randy. The OP is 2 months into this hobby, and has obviously gotten some pretty bad advice from their LFS. Being a beginner, understanding your reef, testing, and why we test, I would NEVER skip testing anything. Nitrite is important, even if not lethal.
Also, you are using tap water? Ditch that for the 55 gallon tank. You want Reverse Osmose, De-Ionized water(RO/DI). This is the purest of the pure water.
Because we generally do NOT know what is in our tap water, it is looked down upon to use it. It may contain many bad things in it, all of which will add a question mark to the tank, and what's going on inside it. Considering the cost of this hobby, spending $150 on a good RO/DI unit is nothing, IMO. A great insurance policy. I think that might have a LOT to do with why your CUC has died. Much more so than 1-2ppm nitrite.
PS, if your LFS is telling you to go without a skimmer, and use tap water, AND that you can keep an angel with a clarki in a 29, go smack him in the face and tell him that you will not be so naiive anymore.