Why is my dose so small for a 50-gallon tank?

Randy Recipe #1 stock is ~1,900 meq/L — incredibly concentrated. About 1.4 mL per US gal raises alkalinity by 1 dKH. For a 50-gal raising 1 dKH, that's ~70 mL of stock. Real concentrated stocks make small doses look tiny; that's the design, not an error.

Recipe #1 versus Recipe #2?

Recipe #1 (baked) raises pH harder; useful if your tank runs 7.8–8.0 and you want to climb. Recipe #2 (unbaked) keeps pH closer to where it sits; useful if your tank is already 8.3+ and you don't want to chase it higher. The Ca side of the recipes is the same either way.

Can I mix BRS Pharma soda ash and Randy at the same strength?

Yes — both target ~1,900 meq/L when mixed at the published ratios. BRS Pharma soda ash is sodium carbonate from the factory (no baking required), so it's faster to mix and slightly more pH-active than Recipe #2.

Why does Triton give grams, not mL?

Triton's CoreChem corrections assume you keep dry sodium bicarbonate on a scale. 3 g NaHCO₃ per 100 L = 1 dKH. They prefer this to liquid stocks because there's no degradation in storage and the math is one-step.

Calculator

Alkalinity Dosing Calculator

Alkalinity is the parameter that punishes inattention the hardest. SPS tissue recession at 6 dKH, burnt tips at 12 dKH, neither one recovering fast. This calculator takes a tank volume, your current reading, your target, and a product, and returns the exact mL of liquid stock or grams of dry powder. Every constant traces back to a primary source — Randy Holmes-Farley's original recipe articles, BRS Pharma mixing instructions, Tropic Marin's product label, Red Sea's manual, or Triton's CoreChem documentation.

Alkalinity dosing

Tank volume (US gal)

Reading unit

Current alkalinity

Target alkalinity

Product / recipe

Required change

1.50dKH

Liquid dose

53.37mL

594 g sodium bicarbonate baked at 300 °F for 1 hr to Na₂CO₃, dissolved to 1 US gal. Stock ≈ 1,900 meq/L.

Source: reefs.com

How this is calculated

Randy Recipe #1 stock = 594 g NaHCO₃ baked → 1 gal solution
                      ≈ 1,900 meq/L

mL_dose = tank_gal × ΔdKH × (3.785 / 1900) / 2.8 dKH-per-meq

For Red Sea Foundation B (1 mL/100 L = 0.034 dKH):
mL_dose = tank_gal × 3.785 × ΔdKH / (100 × 0.034)

For Triton Base 1 (dry):
g_NaHCO₃ = (tank_L / 100) × ΔdKH × 3

Randy Recipe #1 is sodium bicarbonate baked at 300 °F for an hour to convert to sodium carbonate (Na₂CO₃). The conversion drives pH up faster than unbaked baking soda (Recipe #2), which is the right choice if your tank pH is already 8.3+ and you don't want it climbing further. Recipe #2 still works but raises pH ~0.1 less per dose at equilibrium.

All-For-Reef is a special case: it's a balanced maintenance product that supplies Ca + Alk + Mg in the natural ratio of consumption. You can't "raise alk by 1 dKH" with AFR — the math is daily dosing as % of demand. The calculator returns Tropic Marin's recommended starting dose (5 mL / 100 L / day) and the maximum (25 mL / 100 L / day).

Single doses above 2 dKH are flagged as risky. Coral reacts to rate of change, not absolute value. A tank running stable at 6 dKH is healthier than one yo-yoing between 8 and 10 dKH every week.

FAQ

Why is my dose so small for a 50-gallon tank?: Randy Recipe #1 stock is ~1,900 meq/L — incredibly concentrated. About 1.4 mL per US gal raises alkalinity by 1 dKH. For a 50-gal raising 1 dKH, that's ~70 mL of stock. Real concentrated stocks make small doses look tiny; that's the design, not an error.
Recipe #1 versus Recipe #2?: Recipe #1 (baked) raises pH harder; useful if your tank runs 7.8–8.0 and you want to climb. Recipe #2 (unbaked) keeps pH closer to where it sits; useful if your tank is already 8.3+ and you don't want to chase it higher. The Ca side of the recipes is the same either way.
Can I mix BRS Pharma soda ash and Randy at the same strength?: Yes — both target ~1,900 meq/L when mixed at the published ratios. BRS Pharma soda ash is sodium carbonate from the factory (no baking required), so it's faster to mix and slightly more pH-active than Recipe #2.
Why does Triton give grams, not mL?: Triton's CoreChem corrections assume you keep dry sodium bicarbonate on a scale. 3 g NaHCO₃ per 100 L = 1 dKH. They prefer this to liquid stocks because there's no degradation in storage and the math is one-step.

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Sources & references

01
Randy Holmes-Farley — A Homemade Two-Part Calcium and Alkalinity Additive System (Recipe #1)
https://reefs.com/magazine/aquarium-chemistry-a-homemade-two-part-calcium-and-alkalinity-additive-system/
02
Reefkeeping — Recipe #2 and #3A updates
https://reefkeeping.com/issues/2006-02/rhf/index.php
03
Bulk Reef Supply — BRS Pharma Soda Ash Mixing & Dosing
https://www.bulkreefsupply.com/content/post/brs-pharma-soda-ash-mixing-and-dosing-instructions
04
Tropic Marin — All-For-Reef product information
https://www.tropic-marin-smartinfo.com/?lang=en
05
Red Sea — Foundation Complete Manual (Foundation B / KH constants)
https://redseafish.com/wp-content/uploads/2020/11/24653_Manual-Foundation-Complete-GB-_v21a-WEB.pdf
06
Triton — CoreChem product page (Base 1 dosing)
https://www.triton.de/en/products/corechem

Last reviewed 2026-05-25