The accessories that make the biggest difference in a saltwater tank are the ones that handle water chemistry and equipment reliability. A reliable auto top-off (ATO) unit, a quality refractometer, a battery backup for your return pump, and a good set of test kits will do more for your tank than any decorative piece of gear. Beyond those essentials, there's a long list of useful tools that make maintenance easier and less time-consuming.
This guide breaks down saltwater aquarium accessories by category, explains what each does, and gives you specific product recommendations so you know what's worth buying.
Water Level and Salinity Control Accessories
Evaporation is a constant factor in saltwater tanks. As freshwater evaporates, the salinity of what remains increases. A 50-gallon tank can lose half a gallon or more per day depending on temperature, air circulation, and whether you run a sump. Manually topping off every day is tedious and easy to forget.
Auto Top-Off Units
An ATO system uses a float switch, optical sensor, or conductivity probe to detect when the water level drops, then runs a small pump to refill with fresh RO/DI water automatically. The Tunze Osmolator 3155 and Eshopps ATO are among the most reliable designs available. The Neptune Apex ATK is a more advanced unit that integrates with the Apex controller ecosystem and includes dual-sensor redundancy to prevent overflow events.
For a budget-friendly option, the Innovative Marine HYDROFILL Ti ATO costs around $50 and works reliably for smaller tanks. The Tunze 3155 runs about $130 and is the one I'd recommend for tanks over 50 gallons.
Refractometers
You need a refractometer calibrated for seawater (not a general-purpose one) and calibration fluid that traces back to NIST standards. The Milwaukee MA887 is the most commonly recommended option at around $30. Calibrate it monthly or any time you buy a new bottle of calibration solution.
Digital salinity meters like the D-D H2Ocean Pro+ give you precise readings without the color-matching subjectivity of a refractometer, but they cost $80 to $120 and need regular calibration to stay accurate.
Water Testing Accessories
Accurate test kits are non-negotiable in saltwater. The parameters that matter most are alkalinity (dKH), calcium (ppm), magnesium (ppm), nitrate (ppm), phosphate (ppb), and pH. For a cycling tank, add ammonia and nitrite.
Salifert test kits are consistently accurate and easy to read. The Nyos test kits are a step up in precision, especially for alkalinity. For phosphate and alkalinity, the Hanna Checkers (HI713 for phosphate low range, HI755 for alkalinity) give digital readouts that remove the guesswork from color-matching.
A test kit storage box with clearly labeled slots keeps everything organized and prevents reagents from getting mixed up. The API test kit cases that come with their reef master kit work fine for this purpose.
Maintenance Accessories
The tools you use for routine maintenance determine how much time you spend on your tank each week. The right accessories make a big difference.
Magnetic Algae Scrapers
Algae grows on the glass faster than you'd like. A magnetic scraper lets you clean the inside of the tank without reaching in. The Flipper Nano works for tanks up to 1/4-inch glass, the Flipper Standard covers glass up to 3/8 inch, and the Flipper Max handles 1/2-inch glass used in larger tanks. Avoid cheap scrapers with metal blades on acrylic tanks.
Gravel Vacuums and Siphons
Even in a reef with no sand stirring, detritus accumulates in dead spots. A flexible siphon vacuum on a 36 to 48 inch hose lets you reach into the tank and target areas under rocks without disturbing the aquascape. Python No Spill Clean and Fill siphons connect directly to a faucet and drain water while you vacuum.
Turkey Basters and Feeding Tools
A large turkey baster (available for a few dollars) is one of the most useful tools in reef keeping. You use it to blast detritus off rocks, target-feed corals, and spot-clean areas the siphon can't reach easily.
Aquarium Tweezers and Scissors
Long stainless steel aquarium tweezers (12 to 16 inch) let you place frags, adjust small rocks, and remove unwanted pests without reaching elbow-deep into the tank. Curved aquarium scissors (the kind sold for planted tanks) work just as well for trimming soft corals and macroalgae.
Electrical Safety and Backup Accessories
Saltwater and electricity are a dangerous combination. Several accessories exist specifically to manage this risk.
GFCI Outlets
Every outlet powering aquarium equipment should be on a GFCI (ground fault circuit interrupter) circuit. If your tank area doesn't have GFCI outlets built in, plug-in GFCI adapters cost $15 to $20 at any hardware store and can be lifesavers.
Drip Loops
Route every power cord downward in a loop before it enters the power strip or outlet. Water traveling down a cord will drip off the bottom of the loop rather than following the cord into the outlet. This costs nothing and takes 30 seconds to set up.
Battery Backup for Circulation
A power outage lasting more than an hour or two can kill your live rock's bacteria and suffocate fish. A small UPS (uninterruptible power supply) running your return pump and one powerhead buys you 2 to 4 hours during a short outage. The CyberPower CP1500PFCLCD is a popular choice because it has pure sine wave output, which is compatible with variable speed pumps that can be damaged by simulated sine wave UPS units.
Dosing and Supplementation Accessories
As corals grow, they consume alkalinity and calcium faster than water changes alone can replenish. Dosing accessories automate the addition of these elements.
The two-part dosing method (alkalinity solution + calcium/magnesium solution) is the most accessible approach. The BRS Two-Part Dosing Pump kit costs around $60 and includes two peristaltic pump heads you program to dispense a set volume per day. For more precision, the Neptune DOS dosing system integrates with the Apex controller.
For larger or more established reef systems with high coral density, a calcium reactor (which dissolves aragonite media using pressurized CO2 to replenish alkalinity and calcium simultaneously) is more cost-effective long-term. It requires more initial setup but reduces the ongoing cost of two-part solutions.
If you want to compare accessories alongside full filtration and lighting systems, the Best Freshwater Aquarium Accessories guide covers many of the same tool categories with crossover value. For a broader shopping overview including online pricing, the Best Buy Aquarium Accessories Online roundup is worth bookmarking.
FAQ
What accessories do I need to start a saltwater tank?
At minimum: a refractometer for salinity, a thermometer, a hydrometer or digital salinity meter, a basic test kit covering ammonia, nitrite, nitrate, and pH, and an algae scraper. As the tank matures, add an ATO unit, alkalinity and calcium test kits, and a siphon for maintenance.
Are protein skimmer accessories sold separately?
Yes. Replacement impellers, needle wheels, and collection cup gaskets are sold as spare parts by manufacturers like Reef Octopus and Bubble Magus. It's worth having a spare impeller on hand, since a broken impeller is the most common cause of skimmer failure.
How do I keep salt creep under control?
Salt creep happens where water splashes and evaporates, leaving behind salt crystals. Keep a damp cloth nearby and wipe equipment surfaces and the tank rim weekly. Lowering flow near the water surface reduces splash. Some reefers use foam tape around the edge of tank lids to reduce creep in HOB equipment mounting spots.
What's the best way to store coral frags?
A frag rack (acrylic or magnetic-mount) holds coral fragments in the water column where they get good flow and light. Innovative Marine makes popular magnetic frag racks for nano tanks. Larger systems often use standalone frag rack stands placed at the appropriate depth.
Key Takeaways
The accessories that matter most are the ones that prevent problems: an ATO to stabilize salinity, GFCI protection on every outlet, accurate test kits, and a backup power source for circulation. Maintenance tools like a magnetic scraper, flexible siphon, and tweezers make weekly upkeep faster and less stressful. Buy quality versions of the things you use daily, and you'll spend less money over time replacing cheap tools that break.