Recommended Reef Tank Parameters

Maintaining stable water chemistry is one of the most important parts of keeping a successful reef aquarium. Use this guide as a practical reference for mixed reef aquariums and for deciding what to do when a parameter is too low or too high.

Remember: Stability is usually more important than hitting a perfect number. Correct parameters gradually and always re-test before making additional adjustments.

Mixed Reef Quick Reference

These ranges are good general targets for aquariums containing a mixture of soft corals, LPS and SPS corals.

Salinity
1.025–1.026
Specific Gravity
Temperature
77–79°F
Stable temperature
pH
8.0–8.4
Daily variation is normal
Alkalinity
8–9 dKH
Consistency is critical
Calcium
400–450
ppm
Magnesium
1250–1400
ppm
Nitrate
2–15
ppm NO₃
Phosphate
0.03–0.10
ppm PO₄
Calcium & Magnesium: In most normally maintained reef aquariums, calcium and magnesium will remain within an appropriate range when salinity and alkalinity are stable, regular water changes are performed, and a balanced reef supplementation method is used. For this reason, routine calcium and magnesium testing is usually unnecessary for the average reef keeper.
Do not chase numbers. A reef maintaining 8.0 dKH every day is generally preferable to one repeatedly swinging between 8 and 10 dKH while trying to achieve an exact target. Make small changes and watch the trend over several tests.

Salinity

Target: 1.025–1.026 SG

If Salinity Is Too Low

  • Confirm the reading with a properly calibrated refractometer.
  • Replace a small amount of aquarium water with properly mixed saltwater.
  • Raise salinity gradually rather than making a large correction at once.
  • Check for excessive freshwater top-off or an incorrectly calibrated auto top-off system.

If Salinity Is Too High

  • Verify the reading before making adjustments.
  • Slowly add RODI water or replace a small amount of tank water with RODI water.
  • Check whether evaporation has been replaced consistently.
  • Do not make a large salinity change at one time.
Wet Pets Recommendations: Refractometers · Fresh RODI Water · Pre-Mixed Saltwater · Reef Salt Mixes

Temperature

Target: 77–79°F

If Temperature Is Too Low

  • Verify the temperature using a second thermometer when possible.
  • Check heater operation and heater sizing.
  • Increase the heater setting gradually.
  • Avoid sudden temperature changes.

If Temperature Is Too High

  • Check heaters for a thermostat failure.
  • Increase airflow across the aquarium or sump.
  • Reduce excessive heat from equipment when possible.
  • Never rapidly chill an overheated aquarium.

pH

Target: 8.0–8.4

If pH Is Too Low

  • First test alkalinity.
  • Increase surface agitation and gas exchange.
  • Check whether elevated indoor CO₂ may be suppressing pH.
  • If alkalinity is low, correct alkalinity gradually.
  • Avoid adding chemicals simply to chase pH.

If pH Is Too High

  • Verify the test result before taking action.
  • Check alkalinity and review any dosing being added to the aquarium.
  • Reduce or temporarily stop alkalinity additives if alkalinity is also high.
  • Allow the system to return toward normal gradually.

Alkalinity

Target: 8–9 dKH

If Alkalinity Is Too Low

  • Re-test to confirm the reading.
  • Increase supplementation gradually.
  • Determine how much alkalinity the aquarium consumes each day.
  • For ongoing balanced supplementation, All-For-Reef can replace alkalinity and other elements consumed by corals.
  • Avoid large alkalinity increases in a single day.

If Alkalinity Is Too High

  • Stop or reduce alkalinity supplementation.
  • Allow normal coral consumption to gradually lower alkalinity.
  • Perform normal water changes if appropriate.
  • Avoid trying to force alkalinity downward rapidly.
Wet Pets Recommendations: Tropic Marin All-For-Reef · Hanna HI772 Marine Alkalinity Checker
Use Our All-For-Reef Calculator

Nitrate — NO₃

Target: 2–15 ppm

If Nitrate Is Too Low

  • Do not assume zero nitrate is ideal for a reef aquarium.
  • Review feeding and nutrient export.
  • Reduce excessive nutrient-removal media or filtration if appropriate.
  • If nitrate remains at or near zero, carefully dose a reef nitrate supplement.
  • Increase nitrate slowly and re-test frequently.

If Nitrate Is Too High

  • Increase water-change frequency.
  • Remove trapped detritus and clean mechanical filtration.
  • Review feeding quantity and livestock load.
  • Check skimmer and biological filtration performance.
  • Lower nitrate gradually rather than attempting an immediate large reduction.
Wet Pets Recommendations: Brightwell NeoNitro for low nitrate · Hanna HI782 Nitrate Checker · MicroBacter7
Use Our NeoNitro Dosing Calculator

Phosphate — PO₄

Target: 0.03–0.10 ppm

If Phosphate Is Too Low

  • Do not intentionally maintain phosphate at zero.
  • Review feeding and nutrient export.
  • Remove or reduce phosphate-removal media if appropriate.
  • If phosphate remains depleted, carefully dose a reef phosphate supplement.
  • Make very small corrections and re-test frequently.

If Phosphate Is Too High

  • Review feeding and remove accumulated detritus.
  • Perform appropriate water changes.
  • Use phosphate-removal media when necessary.
  • Start with a conservative amount of media.
  • Do not rapidly strip phosphate from a high level to near zero.
Wet Pets Recommendations: Brightwell NeoPhos for low phosphate · Hanna HI774 ULR Phosphate Checker · Seachem PhosGuard for elevated phosphate
Use Our NeoPhos Dosing Calculator

Ammonia & Nitrite

Target: 0 ppm

Normal Reading

In an established reef aquarium, both ammonia and nitrite should normally test at zero.

If Ammonia or Nitrite Is Detected

  • Confirm the reading immediately.
  • Check for dead or decaying animals.
  • Stop adding new livestock.
  • Reduce feeding temporarily if necessary.
  • Perform an appropriate water change.
  • Check biological filtration and circulation.
  • Consider adding live nitrifying bacteria.
Wet Pets Recommendations: Fritz TurboStart 900 Saltwater · FritzZyme 9 Saltwater · Fresh RODI Water
Important: If livestock is showing rapid breathing, severe stress, tissue loss, loss of equilibrium or other sudden symptoms, do not automatically begin adding supplements. First verify salinity, temperature, ammonia, alkalinity and recent changes to the aquarium.

How Often Should You Test?

Testing frequency should increase whenever the aquarium is new, livestock is being added, dosing is being adjusted or something appears abnormal.

Frequently Temperature and salinity
Weekly Alkalinity, nitrate and phosphate
As Needed Ammonia and nitrite when cycling a new aquarium or troubleshooting a problem

These values are general recommendations for mixed reef aquariums. Individual coral species and specialized reef systems may be maintained successfully outside these ranges. Always consider the aquarium's normal baseline and make corrections gradually. If you are unsure what your test results mean, bring your water test results to Wet Pets Aquatics and we can help you determine the appropriate next step.