Decision guide / UK

Do you need to dose a reef tank?

Dosing is not a rite of passage. It is a response to measured consumption that your normal water changes cannot comfortably replace.

Three questions to answer

QuestionIf the answer is noIf the answer is yes
Is there measurable consumption?Do not automate a number you have not observedRepeat tests across a consistent interval and calculate the trend
Can water changes keep up?Regular changes may be the simplest methodCompare the cost, labour and stability of a supplement plan
Can you monitor the result?Fix the testing routine before adding a doserChoose a conservative schedule with a stop rule and review date

Signs that dosing may be premature

  • The tank is new, lightly stocked or still changing week to week.
  • Alkalinity and calcium readings are inside the salt mix’s intended range without a downward trend.
  • You have not repeated the test with clean equipment and the same method.
  • The proposed dose is based on someone else’s tank rather than your measured volume and consumption.

How to prove consumption

Test alkalinity and calcium at a consistent time, record the water-change date and avoid changing several inputs during the observation window. A fall between two comparable readings is evidence of net consumption; one odd result is a reason to repeat the test. Use the additive manufacturer’s calculator only after you have a reliable starting number.

What dosing can and cannot fix

Dosing can replace measured elements that are being consumed. It cannot correct poor salinity control, bad source water, a failed test kit, inadequate circulation or an unplanned nutrient problem. Fix the cause first when the tank is unstable.

Sources and limitations

This page deliberately avoids a universal “dose at X litres” rule. Manufacturer instructions differ in concentration and safe maximums; for example, Seachem’s Reef Fusion guidance asks users to dose by water volume and not exceed its stated daily limit. We have not tested any additive or tank system.

IF DEMAND IS REAL

Choose a pump that can be calibrated and stopped.

Channel count matters less than repeatable output, accessible tubing and a safe failure plan.

Compare dosing pumps