You use a mixture of white and blue light. The tank will not look good with only white. Definitely wait on getting anything new, think months from now. Those leather do not look very health, you have a ton to learn and need to get this tank in good shape before you even think of setting up a quarantine tank to handle new arrival. You have a fish, you have corals. Until you can get those corals growing again I would hold off. Most tanks are built over years not days or months unless you are very experienced. Most people crash their first tank by rushing it. Rushing things will only lead to more problems.