Why dosing matters
SPS and LPS coral consume alkalinity, calcium, and magnesium continuously as they build calcium-carbonate skeletons. A 75-gallon SPS reef can consume 2-4 dKH of alkalinity per day at peak growth. Without replacement, parameters crash within a week and coral begins receding. The four mainstream replacement methods:
Method 1: Two-part (BRS, Tropic Marin Pro)
The foundational approach. Separate alkalinity solution (sodium carbonate / bicarbonate) and calcium solution (calcium chloride), dosed independently via dosing pump. Cheap, simple, scalable.
- Cost: $80 startup (BRS Reef Saver kit), ~$15-25/month consumable for 75g SPS
- Setup: 2 dosing pump heads, 2 reservoir bottles, 2 input lines, daily testing initially
- Best for: SPS keepers who want full control and lowest operating cost
- Trade-off: requires manual magnesium top-up, no trace element delivery
Method 2: Calcium reactor
CO2 dissolves CaCO3 media (aragonite or coarse coral skeleton). Output water is acidic, calcium-rich, alkalinity-rich, and balanced 1:1. Hands-off once dialed but mechanical complexity.
- Cost: $400-1,000 startup (reactor + CO2 cylinder + regulator + solenoid + pH controller). $20-40/month consumable.
- Best for: 100g+ SPS systems with predictable consumption
- Trade-off: learning curve to dial; CO2 cylinder swaps; magnesium still requires separate dosing
Method 3: All-for-Reef (Tropic Marin)
A single solution that delivers calcium, alkalinity, magnesium, and trace elements in marine-balanced ratio. One liquid, one pump, no separate magnesium dosing.
- Cost: $50 starter, $30-60/month for 75g SPS - higher per-gallon than two-part but simpler
- Best for: medium SPS reefers (40-150g) who value simplicity
- Trade-off: single-source dependency (Tropic Marin); higher consumable cost at scale
Method 4: Triton method (ATL)
Three solutions covering all elements coral consumes. Pairs with quarterly Triton ICP testing to dial trace element delivery. Premium European approach with strong following.
- Cost: $80 starter, $40-70/month consumable, $40-50/quarterly ICP
- Best for: serious SPS reefers running 100g+ systems with parameter discipline
- Trade-off: ICP dependency; higher cost; the Triton "no water change" thesis is debated
Dosing pumps
- Kamoer X4 PLUS / X5 PLUS: 4-5 channels, WiFi, $250-350. Hobby standard.
- Apex DOS: $300, 4 channels, integrates with Apex ecosystem
- Hydros XP: $200, 4 channels, simpler than Apex
- BRS / Aqua Lifter peristaltic: $30-60 single channel, manual scheduling, budget option
Which to pick
- First reef tank, soft / LPS: manual top-up + alkalinity buffer when needed. Skip dosing systems.
- Mixed reef under 75g: All-for-Reef + Kamoer X4. Simplest path.
- SPS reef 75-150g: Two-part + Kamoer X4 + manual magnesium. Best cost-to-control ratio.
- SPS reef 150g+: Calcium reactor + two-part backup + Kamoer for trace.
- Premium SPS, parameter discipline focus: Triton method with quarterly ICP.
Dialing in any system
- Test alkalinity at the same time each day for 7 days. Calculate daily consumption.
- Set dose rate to replace consumption + 5% buffer.
- Test again after 7 days. Adjust ±10% to hit your target alk.
- Once stable, test biweekly and adjust seasonally as growth changes.