I would say get conditioner as all tap water I know of has cholorin in it, also the amonia or nitrate levels may not be in balance yet as of the tank being new. As well your plants probably won't suruvive but it is hard to say depending on the type of plant. I started with a ten gallon so I don't know if the testers are worth getting for you or not, but my assumption would be not all the bacterial balances have been met yet as it is a new tank setup so your nitrates and amonia will be offbalanced at least to start.