Core7 Withdrawal Calculator
WithdrawalCalculator
The Core7 Withdrawal Calculator determines how much aquarium water to remove daily when salinity rises due to Core7 Base Elements supplementation. Enter your daily Core7-1 dose and get the exact withdrawal volume to maintain stable salinity at 35 ppt.
Calculate Your Daily Withdrawal
Core7 Withdrawal
When you dose Core7 Base Elements daily, the added liquid volume can gradually raise your aquarium's salinity. This calculator tells you exactly how many litres of aquarium water to remove each day to counteract that increase and keep salinity stable at 35 ppt. You only need to withdraw water and use this calculator if your salinity is rising. Do not withdraw any water if this is not the case.
Daily Water Withdrawal
Enter your Core7 Base Elements 1 daily dose
Base Elements 1
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Base Elements 2
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Base Elements 3a
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Base Elements 3b
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Amount of Core7 Base Elements 1 dosed per day in ml
Water to Remove Daily
—ml
This value is a guideline. Actual withdrawal may vary depending on your protein skimmer efficiency and evaporation rate. Monitor salinity weekly with a calibrated refractometer and adjust as needed.
Regular water withdrawal is a simple routine that prevents salinity creep — the gradual increase in dissolved solids caused by concentrated supplementation. A few minutes per day keeps parameters stable and avoids weeks of troubleshooting.
Why Water Withdrawal Matters
Salinity Management for Core7 Users
TRITON Core7 Base Elements is a 4-part liquid supplementation system that provides calcium, magnesium, alkalinity, and trace elements in balanced ratios derived from over 500,000 ICP-OES water analyses. When dosed daily, the added liquid volume introduces dissolved solids that can gradually raise salinity above the target of 35 ppt. Removing a calculated volume of aquarium water each day — without replacement — offsets this increase.
You only need to withdraw water and use this calculator if your salinity is rising. Do not withdraw any water if this is not the case.
Equal dosing across all bottles — All four Core7 bottles (1, 2, 3a, 3b) are dosed in equal amounts. Enter your Core7-1 dose in the calculator and the same volume applies to every bottle.
Not a water change — Water withdrawal removes a small volume of aquarium water each day without replacement. This is distinct from a water change, which replaces removed water with freshly mixed saltwater.
Skimmer efficiency matters — A protein skimmer exports dissolved organics in concentrated skimmate, which also removes some dissolved solids. More efficient skimmers reduce the withdrawal needed.
Verify with ICP testing — An ICP-OES analysis every 2–3 months confirms your salinity, element levels, and overall water chemistry are within optimal range.
Practical Guidance
Keeping Salinity Stable
Measuring Salinity Accurately
Use a calibrated refractometer, ICP test, or a high-grade hydrometer for reliable salinity readings. Calibrate with a 35 ppt reference solution, not RO water. Take readings at the same time each day, at consistent temperature (25 °C), for comparable results.
Target salinity for reef aquariums: 35 ppt (1.026 specific gravity). Act if readings consistently exceed 36 ppt.
Adjusting Your Withdrawal
You only need to withdraw water and use this calculator if your salinity is rising. Do not withdraw any water if this is not the case.
If your salinity is rising, start with the calculated volume and monitor salinity for 1–2 weeks. Adjust based on what you observe:
- Salinity still rising — increase withdrawal by 10–20%
- Salinity dropping — decrease withdrawal by 10–20%
- Salinity stable — your current volume is correct
Seasonal changes in evaporation rate (summer vs. winter) may require periodic adjustments.
Common Questions
Frequently Asked Questions
Core7 Base Elements are concentrated liquid supplements that add dissolved salts to your aquarium water. When these salts accumulate, the overall salt concentration — measured as salinity — increases. Removing a small calculated volume of aquarium water daily offsets this addition and keeps salinity within the optimal range of 35 ppt (1.026 specific gravity).
No. A water change involves removing aquarium water and replacing it with freshly mixed saltwater. Water withdrawal for salinity management removes a small amount of aquarium water, replacing it with freshwater (auto top-up). The volume removed is typically much smaller than a water change — often just a few hundred millilitres per day — and serves only to counteract the salinity increase caused by supplementation.
All four Core7 Base Elements bottles are dosed in equal amounts. If you dose 40 ml of Core7-1, you also dose 40 ml of Core7-2, 40 ml of Core7-3a, and 40 ml of Core7-3b — 160 ml total per day.
Check salinity at least once per week when first establishing your dosing routine. Once your system is stable and the withdrawal volume is dialled in, checking every 1–2 weeks is sufficient. Use a calibrated refractometer for accurate readings. Target salinity is 35 ppt (1.026 specific gravity). An ICP-OES test every 2–3 months provides a comprehensive overview of all water parameters including salinity.
Yes. Protein skimmers remove dissolved organics in a concentrated skimmate, which also exports some dissolved solids. A more efficient skimmer may reduce the amount of water you need to withdraw, while a less efficient one may require slightly more. The calculator provides a guideline — monitor your actual salinity readings and adjust the withdrawal volume accordingly.
Looking for other dosing tools? Try the Infusion Dosage Calculator for trace element dosing.
Stable Salinity Starts With Data
An ICP-OES analysis measures 45 water parameters at parts-per-billion precision — including salinity, calcium, magnesium, and every trace element Core7 provides. Use it to confirm your dosing and withdrawal are working.