Water Parameters for a thriving reef
Stability is King: Your Essential Guide to Perfect Reef Tank Water Parameters
Creating a thriving coral reef in your living room is one of the most rewarding hobbies, but it requires diligent care—especially when it comes to water chemistry. Unlike a fish-only tank, corals, clams, and other invertebrates are extremely sensitive to fluctuations. In the reef keeping world, the mantra is clear: Stability is King!
Here is your essential guide to the ideal reef tank parameters and the best solutions for keeping them in check.
The Big Three: Core Reef Parameters
These three parameters are essential for coral growth (calcification) and a stable environment. Test them regularly, as they are consumed by your corals and need to be replenished.
|
Parameter |
Ideal Range |
Why It's Important |
Correction Solutions |
|
Alkalinity (dKH) |
7-8.5 dKH |
Measures carbonate hardness, which is critical for buffering and for coral skeletal growth. |
Low: Dose a quality alkalinity buffer or a 2-part solution. High: Perform a water change or, if only slightly high, simply wait as corals will consume it over time. |
|
Calcium (Ca) |
400-440 ppm |
A major building block for coral skeletons and coralline algae. |
Low: Dose a calcium supplement (liquid or solution). High: Stop dosing for a few days, perform a water change, and ensure your magnesium is in check. |
|
Magnesium (Mg) |
1280-1320 ppm |
Helps maintain the proper balance of calcium and alkalinity by preventing calcium carbonate from precipitating out of the water. |
Low: Dose a magnesium supplement. High: A partial water change is the best way to slowly bring down high levels. |
The Absolute Essentials: The Baseline
These are fundamental to all marine life and must be kept within tight ranges.
|
Parameter |
Ideal Range |
Why It's Important |
Correction Solutions |
|
Salinity |
1.024-1.026 (Specific Gravity) (32-35 ppt) |
The measure of salt in your water. Major swings can cause osmotic shock to fish and invertebrates. |
Low: Slowly increase salinity by topping off with mixed saltwater (instead of freshwater ) over several days, or by performing water changes with saltier water. High: Replace small amounts of tank water with an equal amount of fresh water over several days. Always use an Auto Top-Off () with water to prevent high salinity from evaporation. |
|
Temperature |
77-80 Degrees F |
Corals and fish are cold-blooded and are stressed by rapid temperature changes. |
Use a reliable heater and/or chiller, and maintain a constant temperature. Temperature should not fluctuate more than a couple of degrees in a day. |
|
pH |
8-8.4 |
A measure of acidity/alkalinity. A stable is vital for calcification. |
Low: Ensure proper gas exchange (surface agitation, air-draw skimmers). If still low, use buffers or, for advanced users, a calcium reactor. |
Export to Sheets
The Waste Products: Keep Them Low
These are the byproducts of your tank's nitrogen cycle and nutrient intake. High levels can encourage nuisance algae and harm corals.
|
Parameter |
Ideal Range |
Why It's Important |
Correction Solutions |
|
Ammonia |
0 ppm |
Highly toxic to all marine life. A sudden spike indicates a problem with the biological filter. |
Non-Zero: Immediate water change, add a chemical ammonia binder, and investigate the cause (e.g., dead fish, new rock). |
|
Nitrite |
0 ppm |
Highly toxic. Should be zero once the tank is fully cycled. |
Same as Ammonia. |
|
Nitrate |
8-12 Ppm |
Excess leads to nuisance algae growth and can irritate corals. |
High: Perform water changes, reduce feeding, use macroalgae in a refugium, employ nitrate-reducing media/bacteria, or use a protein skimmer. |
|
Phosphate |
.05-.10 Ppm |
Feeds unwanted algae and can inhibit coral growth and calcification. |
High: Water changes, use (Granular Ferric Oxide) or other phosphate-removing media, reduce feeding, and physically remove any excess detritus. |
Final Thoughts on Stability
It's tempting to panic and dump chemicals into your tank when a parameter is out of range, but the best approach is always slow and steady. Rapid changes are often more stressful for your livestock than being slightly outside the "perfect" range.
- Test Regularly: Use high-quality test kits or a reliable electronic monitoring system weekly.
- Calibrate Your Tools: Ensure your refractometer is calibrated monthly with a dedicated calibration solution, not just fresh water.
- Adjust Gradually: When making corrections, aim for a gradual shift over several days or even weeks. For instance, only lower or raise salinity by about per day.
By committing to regular testing and maintaining stability in the core parameters, you'll be well on your way to a beautiful, thriving reef aquarium!