Tenji is pleased to present a series of exclusive articles for Reef2Reef members. We will be delving into the various aspects of reef keeping, focusing on tried and true methods that can be implemented by aquarists of all levels. _____________ Our first installments will be concentrating on the most basic aspect that is frequently overlooked; your source water. Once you are producing 0 TDS water from your RO/DI system it’s time to create the ideal reef water by mixing in a synthetic salt. I’m a firm believer you can be successful using any quality salt mix. Very few large salt producers have recurring contaminant issues, so once you find one you like that mixes to the appropriate parameters we recommend you stick with it. All salt mixes contain the same base component, sodium chloride, or NaCl. There are only two major suppliers of NaCl in the United States, meaning all of the major salt companies pull from just two sources. We start to see what sets them apart when it comes to the remaining components of a synthetic salt mix, beginning with the magnesium sulfate, or MgSO4. There are various grades of magnesium sulfate available to salt manufacturers ranging from US Pharmaceutical grade to agricultural grade, which is indicative of purity. Many lower purity magnesium sulfate crystals contain anti-caking agents which we wind up seeing stuck all over the inside of our mixing barrels. The jury is still out whether this is detrimental to aquaria long-term, but overall most agree while this is unsightly, it has no direct negative effect. Then major and minor trace elements are added, and as you can probably guess, like magnesium sulfate they are offered in various grades. Cost for the different classifications directly correlates to the price of our salt. Generally speaking, the higher priced salts use purer components. Some companies go even further by solubilizing components to further filter contaminants, which is why we see some salts coming in multiple parts that include liquids. Ultimately most quality salt choices are pretty similar, so the next thing to consider is your target parameter range. If you intend to keep alkalinity at 7 dKH you should search for a synthetic salt that mixes close to 7 dKH. Using a salt that mixes to 10 dKH would inevitably stress your animals in your display running at 7 dKH every time you do a water change. The same can be said regarding other elements; if your target calcium level is 350 ppm avoid a salt that mixes to 450 ppm. Next thing to consider is availability and cost. If you live in New York, you don’t want to source a salt that’s commonly used in Los Angeles but rarely seen on the east coast. Most local fish stores competitively price salt making them a great place to search for your favorite mix and avoid the cost of shipping a box of minerals across the country. Try to resist the urge of being an early adopter of the next greatest salt mix on the market. New mixes might have supply or consistency issues early on forcing you to change salts. Ideally, you have a mixing container large enough to dump your entire package of salt mix in. Many of us won’t have that pleasure, so break out the measuring cups! If you are not using an entire package you should thoroughly mix up the contents prior to use. Those dry components we looked at earlier have diverse particle sizes causing some of them to settle out during shipment. It’s very possible to find varying parameters out of the same package if not blended prior to use. Once your RO/DI water has filled your mixing reservoir it’s time to heat it up. Salt mixes faster and thoroughly at temperatures above 70°F (21°C). Along with a heater, a decent size powerhead or submersible pump will dissolve the salt mix post haste. Don’t skimp on the pump or you might wind up spending additional time helping the salt dissolve. Find a pump that will keep the surface of the water churning. Some salt manufacturers recommend mixing for 24 hours, however, there are now several options that can be used in as little as fifteen minutes. Keeping your reservoir full of ready to use saltwater can save your system in an emergency. Having a 100% water change handy is ideal, although aiming for 50% total system volume would be a more realistic goal. If you intend to store saltwater long-term we recommend you keep it lightly aerated with a pump to prevent elements from precipitating out of solution. That wraps our take on source water, in our next article we’ll start discussing the fun stuff… equipment!