Saltwater Aquarium Salt Mix Guide: Choosing & Mixing Salt

Choosing and mixing salt is one of the most basic skills in the saltwater hobby — and one folks rarely think about until something goes wrong. At Tropical Treasures in Cheyenne, we walk new reefers through this all the time. Here's how to pick a salt and mix it the right way.

Reef salt vs. fish-only salt 🧂

Most brands sell a standard mix and a higher-end reef mix. Reef salts have elevated calcium, alkalinity, and magnesium to support coral growth, while basic mixes are fine for fish-only tanks. If you keep coral, go with a reef-grade salt.

Always start with RO/DI water 💧

Salt mix is designed to be added to pure water. Mixing into tap water layers in unwanted phosphate, nitrate, and metals on top of the salt, so always start with RO/DI. See our RO/DI water guide for why this matters so much.

How to mix salt correctly 🪣

Add salt to water (not the other way around), use a powerhead or pump to circulate, and let it mix and aerate for a few hours — ideally overnight. Then check salinity with a refractometer and adjust before the water ever touches your tank.

What salinity should you target? 🌡️

For a reef tank, aim for about 1.025 specific gravity (roughly 35 ppt). Keep it stable — swings stress corals and inverts more than the exact number. Match your top-off and new mixed water to your display so you never shock the system.

Which salt should you buy? 🤔

Pick a reputable reef brand, then stick with it — switching salts can shift your parameters. Stop in at Tropical Treasures in Cheyenne and we'll point you to a salt that fits your tank, or browse our salt and supplies and call 307-369-1118 with questions.

The bottom line ✅

Use a reef-grade salt with RO/DI water, mix and aerate before use, and verify salinity with a refractometer every time. Consistency is what keeps your reef stable. Not sure which salt is right for you? Stop by Tropical Treasures in Cheyenne or call 307-369-1118, and find more reef tips on The Tank Buddy Blog.