First off, how big is the tank? Second, is this a space or money issue? There are alternatives, but if we don't know the reasons why, we can't offer up suggestions.
Home depot has ~40 gallon brute trashcans for a couple of bucks. These are more than enough to mix new water in. No big deal if you've got to make multiple batches. Mix it up anywhere, garage, basement, etc. The gray ones are saltwater and food safe. They store easily, and don't really take up much space.
You need at least an RO if you are going for a reef tank, RO/DI even better depending on the quality of your tap.. You can get a RO/DI pretty inexpensively nowadays, no need going with a fancy name RO/DI, you can get a great unit from AirWaterIce for less than $200. You don't want to be carting water around, it's going to get more expensive than a RO/DI very quickly. A Ro/Di is an investment, it saves you money and time in the long run.
Do not use tap, even for curing, you can potentially be adding a massive amount of nutrients, metals, ammonia, copper, and worst of all, chlorine and chloramine to your tank. You don't want to expose your rock to this mess, it may become a sink for those nutrients and reward you with a very long and nasty
algae bloom This is not a good way to start your tank. Other issues with using tap include cloudy water from high mineral content causing preciptation of calcium carbonate..
Do not mix saltwater in metal pots, even stainless steel ones. It's always good practice to never let your pure water or saltwater ever come in contact with any metals, especially ones whose content and stability in saltwater is unknown. There is only one exception to this rule, and that is the metal heat exchanger in a chiller, which is usually titanium.
Ah, one last piece of info, do not mix up the water in your tank unless your tank is empty, you'll likely kill off everything in the tank by doing that. Freshly mixed saltwater is not marine life friendly.
jb
hay man, big is this tank?
