Dosing pumps add stability to reef tanks. They deliver small, repeatable doses each day. This guide helps you set one up with confidence.

Plan your dosing and pick safe starting targets

Start with a clear goal for each channel. Common uses are alkalinity, calcium, and magnesium. Many reefers also dose kalk, nitrate, or phosphate solutions. Choose what your tank truly needs.

Test for seven days before you dose anything. Measure alkalinity at the same time daily. Track calcium and magnesium twice that week. Your average daily drop sets your first dose.

A good example is alkalinity falling from 8.3 to 7.6 dKH in 24 hours. That is a 0.7 dKH daily demand. You then calculate how much solution restores 0.7 dKH. Use your supplement label for exact strength.

Set conservative targets and avoid chasing numbers. Many mixed reefs do well at 7.5–9.0 dKH. Keep calcium near 400–450 ppm. Keep magnesium near 1250–1400 ppm. Stability matters more than perfection.

• Test salinity at 35 ppt and temperature at 25–26°C first.
• Only dose what your tests show is being consumed.
• Change one variable per week to avoid confusion.

For baseline care, review your reef tank water parameters. If you run two-part, also check alkalinity and calcium balance.

Install hardware, route tubing, and calibrate each head

Mount the dosing pump above the sump waterline. This reduces siphon risk. Use rigid mounts and avoid sharp tubing bends. Keep lines labeled by channel and solution.

Place dosing containers in a stable, shaded area. Use lids to reduce evaporation and contamination. Run intake lines with a small weight or clip. Keep the intake off the bottom to avoid sludge.

Calibrate every pump head with a measuring cylinder. Many heads vary by 5–15%. Program the pump to run 100 mL. Measure the actual output and enter that value. Repeat twice and average the result.

Add check valves only if your setup needs them. They can clog with kalk or additives. A safer method is a drip loop and high mounting. Also keep the dosing outlet above the water surface.

• Use 1/4 inch dosing tubing and replace it every 6–12 months.
• Keep alkalinity and calcium outlets 6–12 inches apart in the sump.
• Rinse tubing with RO/DI water before first use.

If you plan to automate more tasks, see our reef tank automation basics. It helps with safe cable and drip loop planning.

Program a schedule, verify results, and troubleshoot problems

Split the daily dose into many small events. Aim for 8–24 doses per day for alkalinity. This reduces pH swings and localized precipitation. Calcium can match that schedule or run opposite alkalinity.

Start at 70–80% of your calculated daily dose. Then test alkalinity daily for three days. Adjust by 5–10% at a time. Wait 48 hours between changes when possible.

Watch for common mistakes during week one. A reversed line can dose the wrong chemical. A loose fitting can draw air and under-dose. A submerged outlet can back-siphon and empty a container.

Look for warning signs in the tank. White crust on heaters suggests precipitation. Cloudy water after dosing points to too much, too fast. Rising alkalinity with stable calcium can mean a testing error or low demand.

• Set maximum daily limits in the controller, if available.
• Use a dosing log with date, test result, and dose change.
• Clean pump rollers monthly to keep flow consistent.

As a real example, a 75-gallon reef may consume 10–20 mL of two-part daily. A heavy SPS tank can use 60–120 mL daily. Your numbers will differ. Let your tests guide the schedule.

Once stable, reduce testing but do not stop. Test alkalinity twice weekly. Test calcium and magnesium every one to two weeks. Recalibrate pump heads every two to three months.

Sources: Reef Chemistry by Randy Holmes-Farley (advancedreefkeeping.com articles); Two-Part Dosing Instructions from major supplement labels; Neptune Systems and GHL dosing pump manuals.

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