thats going to present a problem. Tap water has so much material in it that is just not good for keeping corals and inverts in a saltwater tank. Phsphate causes a ton of algae growth and you will for sure get bubble algae which is a huge pain, next to hair algae. Copper which will most likely kill any shrimp you plan on adding and most likely your coral as well. Silicates, which will also aid in the growth of algae, high Nitrate levels which will not help you because those have to be very low, at the most 10ppm and thats almost right out of the tap. i could keep going but i hope you get the point lol. Thats the reason for going with Reverse Osmosis water. You going to be spending a lot of money going through corals and inverts, so just invest in the RO unit right away.