Reef Tanks on a Budget (Part 6): Water and Salt

Reef Tanks on a Budget (Part 6): Water and Salt

In the 6th installment of this multipart series, Reef Tanks on a Budget (Part 6) Water and Salt, we will go over water and salt options for your reef tank.

Editor’s Note: If you haven’t already, please give Part 1, 2, 3, 4, and 5 a read first:

Good water and salt are vital for the success of a reef tank. Regular water changes remove waste, like fish poop, and nutrients, like phosphate, and a good, quality salt will help replenish key parameters like calcium and alkalinity.


A successful reef tank needs proper fresh water to mix with salt. Adding water straight from the tap will likely contain phosphates, nitrates, and other contaminants and is a surefire way to have your reef tank fail.

Corals need low levels of nitrate and phosphate to thrive. However, high levels can cause the proliferation of nuisance algae, browned out corals, cyanobacteria, discolored tank water, and other issues. One of the best ways to make reef-ready freshwater is by running tap water through an RO-DI (Reverse Osmosis and Deionization) water filter.

RO-DI filter

An RO-DI filter forces water through a membrane filter cartridge that rejects even the tiniest of particles. The result is virtually 100% pure water. RO-DI filters come in a variety of configurations and brands. Generally, the more stages, the higher the cost. Most units can produce a minimum of 50 gallons per day (GPD) and as high as 300 GPD. The higher the production capacity, the higher the cost.

In addition to the up-front cost, plan to regularly replace all the filters in your reverse osmosis system. The more water you make, the more often they will need to be replaced. A built-in or hand-held TDS meter is an excellent tool for tracking how well the filters and DI resin are performing and when to replace them.

Budget Recommendation: A basic 4-Stage RO/DI unit will be adequate for most hobbyists. 


Reef salt parameters vary widely, so it is crucial to pick a salt mix that best matches your reef tanks needs. While there is generally nothing wrong with salt from brand to brand, each salt mix has a unique combination of alkalinity, calcium, and other parameters. Due to these differences, some salt mixes are better for use with FOWLR tanks (fish only with live rock), while others are better for high-end SPS coral tanks.

When choosing a reef salt, review the estimated parameters for each salt mix and do your best to match your target calcium and alkalinity levels. If your target KH level is 7, choose a salt with an alkalinity level of approximately 7 and not one near 10. Carefully read the instructions with each salt as the mixing instructions vary from mix to mix. Always start with clean RO-DI water at the same temperature as your display tank, and carefully follow the mixing instructions, so you don’t over or under mix.

Types of Salt

Basic Marine Salt: Basic salts formulated to mimic natural seawater parameters. Best used for fish-only and reef tanks with soft corals only. It is generally cheaper for tanks with hard corals to go with a reef specific salt to reduce how much additives you’ll need.

Popular Examples: Instant Ocean, Tropic Marin, and Red Sea (blue bucket), to name a few. 

Reef Specific Salt: Reef specific salts have higher amounts of calcium, magnesium, and trace elements than basic reef salts. These parameters are essential for your corals to grow and thrive, especially as they begin to grow.

Popular Examples: Instant Ocean Reef Crystals, Red Sea Coral Pro, Aquaforest Reef Salt, and Fritz RPM, among many others. 

Specialty Salts: Specialty salts generally include higher amounts of specific elements, like alkalinity or probiotic bacteria. They are typically reserved for the more experienced hobbyists as they require more knowledge and know-how to use.

Popular Examples: AquaForest Probiotic, Fritz Redline, Reef Microbe-Lift Organic Active Reef Salt, and more.

Instant Ocean400111350
Reef Crystals490131440
Red Sea4107.71280
Red Sea Coral Pro45012.21340
Kent Marine5408.51200
Seachem Reef540101450
Tropic Marin375101230
Tropic Marin Pro Reef4508.51380
Fluval Sea4908.61425
Fritz RPM4208.51350
Fritz RPM Redline42010.51350
Microbe-Lift Reef Salt4208-101460

Budget Recommendation: Although more expensive than basic marine salt, reef specialty salt is generally the preferred option for reef tanks, especially those with hard corals.

Mixing reef salt in fresh RO water and making sure to choose a reef salt that fits both your budget and tank’s needs is essential for success. Starting your reef tank off right with quality freshwater and quality salt is the best way to a happy and healthy tank.  Happy Reefing!

Have a question or feedback for us? Give us a shout by clicking here to contact us, we’d love to hear from you!