A dosing pump with a tank (also called a dosing container or reservoir) is a peristaltic pump unit that automatically dispenses measured volumes of aquarium supplements from a dedicated storage bottle into your tank on a timed schedule. The "tank" in this context refers to the solution container, not your aquarium. Most reef keepers buy dosing pumps and containers separately, but some systems come bundled together, which simplifies setup and ensures the tubing, container caps, and pump heads are matched from the start.
This guide covers how to set up a dosing pump with a dedicated solution tank, which container sizes work best for different tank volumes, how to keep your solutions stable over time, and what the full two-part dosing setup looks like in practice.
Why the Dosing Container Matters More Than Most People Think
The dosing container affects three practical things: how often you refill, how long your mixed solutions stay usable, and whether you have contamination problems.
Container Size and Refill Frequency
If your reef tank consumes 50 mL/day of alkalinity solution and 50 mL/day of calcium solution, container size directly determines your maintenance schedule:
- 500 mL containers: Refill every 10 days
- 1 liter containers: Refill every 20 days
- 2 liter containers: Refill every 40 days
Most hobbyists land on 1-2 liter containers as the sweet spot. Large enough for monthly refills, small enough that solutions don't sit for months before being used (which can affect stability).
Heavy SPS reefs with higher consumption may use 4-liter containers to extend refill intervals to 4-6 weeks. This is particularly useful for magnesium, which is added less frequently.
Solution Stability in Storage
Two-part supplements degrade at different rates: - Alkalinity (sodium bicarbonate or sodium carbonate solutions): Stable for months in a sealed container. Fine to pre-mix in large batches. - Calcium chloride solutions: Stable, but highly hygroscopic (absorbs moisture). If containers aren't sealed well, calcium chloride can precipitate. - Magnesium solutions: Mix of magnesium chloride and magnesium sulfate, stable for months. - Amino acids and organic compounds: Some degrade within weeks after mixing, especially in warm conditions.
For organic supplements (amino acids, carbon sources, bacteria supplements), use 250-500 mL containers and refill weekly rather than larger containers you'd refill monthly. Degraded supplements are either ineffective or, in the case of bacterial supplements, can produce unwanted biological activity in the container.
Contamination Prevention
Dosing containers need caps or lids with tube access holes that prevent contaminants from getting in. Dedicated dosing system containers like the Kamoer dosing bottles, IceCap dosing jugs, and Reef Factory containers are designed with tight-fitting caps that have two holes: one for the intake tube to the pump, one for ventilation or a second tube.
Generic water bottles or pitchers work physically but aren't ideal because the openings are larger and harder to seal around tubing without DIY modifications.
Choosing Containers for Your Dosing System
You don't have to buy the brand-matched containers for most dosing pumps. The tubing size matters more than the container brand.
Matching Tubing and Caps
Most peristaltic dosing pumps use either 3mm ID or 4mm ID silicone tubing. The intake tube goes from the pump head down into the solution container. If you're using third-party containers, you need caps with holes or fittings that match your tubing diameter.
A simple solution: drill a hole in a standard plastic container lid sized for a tight fit over your tubing. The tube hangs into the container, the cap holds it in place. This works perfectly well and costs nothing.
BRS Two-Part Containers
BRS (Bulk Reef Supply) sells 1-gallon and half-gallon jugs that work well as dosing containers. Their standard two-part containers include a dispensing fitting. At 1 gallon (3.78 liters) per container, this is larger than most hobbyist setups need for a single solution type, but they work well if you have high consumption or want infrequent refills.
Reef Factory Container Bundle
Reef Factory sells their dosing pump with matched 1-liter containers that include a dedicated cap with pre-drilled tube ports. For Reef Factory pump users, these are convenient but not necessary. Their 4-head system comes with two containers standard; additional containers are available separately.
For pump comparisons, see our Best Dosing Pump for Reef Tank guide.
Complete Two-Part Dosing Setup: From Scratch
Here's how a complete dosing pump and container setup looks in practice for a 100-gallon mixed reef.
What You Need
- Dosing pump (2-head minimum for calcium and alkalinity, 3-4 heads to add magnesium and trace elements)
- 2-4 dosing containers, 1-2 liters each
- Two-part supplement or DIY ingredients
- Dosing tubes (usually included with the pump)
- Digital scale accurate to 0.1g (for DIY two-part mixing)
- Testing kit for calcium, alkalinity, and magnesium (Salifert or Hanna Checkers are common)
Determining Your Dosing Needs
Test your current calcium and alkalinity levels. The goal for most reefs is: - Calcium: 400-450 ppm - Alkalinity: 8-12 dKH - Magnesium: 1250-1350 ppm
Do a manual test on Monday, do nothing, test again on Thursday. The drop in 72 hours is your consumption rate. Multiply by (365/3) to get approximate annual consumption, then divide by 365 to get daily needs.
For a 100-gallon mixed reef with moderate LPS coral, typical consumption is 20-50 mL/day of each two-part component. For heavy SPS, this can reach 80-150 mL/day.
Mixing Two-Part Solutions
The most cost-effective approach for high-consumption reefs is mixing your own two-part solutions from bulk dry chemicals:
Part 1 (alkalinity): Dissolve 196g of sodium bicarbonate (baking soda, food grade) or 143g of sodium carbonate in 1 liter of RO water. This produces a solution approximately equivalent to the alkalinity portion of commercial two-part.
Part 2 (calcium): Dissolve 147g of calcium chloride (food grade, not road salt grade) in 1 liter of RO water.
The cost difference is significant: DIY bulk two-part costs roughly $0.05-0.15 per mL, while commercial pre-mixed two-part runs $0.25-0.50 per mL. For a reef consuming 100 mL/day of each component, that's a savings of $300-600 per year.
Never mix Part 1 and Part 2 together. They precipitate as calcium carbonate (chalk) immediately when combined. Keep them in separate containers, dosed through separate pump heads.
Programming the Dosing Schedule
Distribute daily doses across multiple time intervals. For 40 mL/day total per component, program 8 doses of 5 mL each, every 3 hours. This keeps alkalinity variation below 0.3 dKH per day.
Test parameters twice weekly for the first month while calibrating the system. Once stable, weekly testing is sufficient for most systems.
Placement and Plumbing
The dosing containers usually live next to or beneath the aquarium stand, with tubes running up into the sump. Keep tubes as short as practical to minimize dead volume in the line (the small amount of solution trapped in the tube between doses).
Keep the tubes separated so calcium solution doesn't contact alkalinity solution anywhere in the line run. If they mix in the sump, calcium carbonate precipitation happens locally but disperses harmlessly. If they mix in the tube, you get a blockage.
Mount dosing containers on a stable surface where they won't tip. If a container tips and the tube falls out, the pump may run dry and pull air. Most pumps handle this without damage, but empty doses mean your parameters drift.
Our Best Aquarium Dosing Pump guide covers specific pump models and their container compatibility in more detail.
Monitoring and Alarms
Once your system is running, the main maintenance tasks are:
Weekly: Check solution levels in containers. Top up before empty.
Bi-weekly: Test calcium and alkalinity. Adjust dose if needed.
Monthly: Calibrate pump heads. Peristaltic tubes wear and flow rates drift.
Quarterly: Replace tubing or check for kinks, which restrict flow.
Most modern dosing pump apps (Reef Factory, IceCap, Kamoer) have low-level alerts that notify you when containers drop below a set level. These alerts are useful but aren't a substitute for visual checks: sensors can fail.
FAQ
How big should my dosing containers be for a 200-gallon SPS reef? At typical SPS consumption rates of 80-120 mL/day per component, a 2-liter container lasts 17-25 days. 4-liter containers extend this to 5-7 weeks. Most serious SPS reef keepers use 4-liter or larger containers to reduce refill frequency. If you're using commercial pre-mixed two-part, 1-gallon (3.78 liter) containers are a convenient size.
Can I use one container to dose multiple supplements in sequence? No. Each solution needs its own dedicated container and pump head. Running different solutions through the same tube causes contamination at the tube walls and potentially precipitation where solutions mix. Peristaltic pump heads are inexpensive and the standard practice is one head per solution type.
Should dosing containers be kept in the dark? For standard calcium and alkalinity solutions, light exposure isn't a concern. For supplements containing bacteria or algal concentrates, refrigeration and light exclusion extend shelf life. Opaque containers or cabinets that block light are a good habit for organic-based supplements. For standard inorganic two-part solutions, any clean container works.
How do I fix a clogged dosing tube? Remove the tube from the pump head and try to flush it with warm water. If the clog is calcium carbonate (from calcium solution), flush with a dilute vinegar solution (5% acetic acid). For stubborn blockages, replace the tube. Dosing tubes are inexpensive ($5-15 for a set) and keeping spares on hand means you never have to wait for a delivery when one fails.
Conclusion
A dosing pump with a properly sized container is one of the most effective ways to maintain stable calcium and alkalinity in a reef tank without daily manual additions. The container size is a practical choice: match it to your consumption rate so you're refilling monthly rather than weekly. Use separate containers for each solution, distribute doses throughout the day in small increments rather than one large dose, and calibrate your pump heads quarterly. That discipline pays off in more stable water chemistry and healthier coral growth.