Methods and sources

Units and constants

• 1 US gallon = 231 cubic inches = 3.785 411 784 L, and 1 inch = 2.54 cm exactly (NIST¹).
• 1 ppm in water is taken as 1 mg/L.
• 1 German degree of hardness (°dH) = 10 mg/L CaO = 0.1783 mmol/L = 17.848 ppm as CaCO₃ (Wikipedia²). GH and KH both use it.
• 1 meq/L of alkalinity = 2.8 dKH, as Seachem states it (Seachem³).

Chemistry

Molar masses are summed from the IUPAC CIAAW standard atomic weights (IUPAC CIAAW⁴). The share of a nutrient in a salt is its mass in one formula unit divided by the molar mass, including any water of crystallization. A few of the results, so they can be checked: KNO₃ is 61.33% NO₃ and 38.67% K; KH₂PO₄ is 69.79% PO₄ and 28.73% K; K₂SO₄ is 44.87% K; MgSO₄·7H₂O is 9.86% Mg. The same weights give the label conversions: P₂O₅ × 1.338 = PO₄ and K₂O × 0.830 = K.

The trace mix (CSM+B) is a blend, so its shares are the guaranteed minimums on the bag (NilocG Aquatics⁵; base CSM Master Plant-Prod⁶).

Tank volume

Inner dimensions are outside length and width less two glass thicknesses, and height less one. Water depth is that height less the gap to the water line. The substrate bed is the inner footprint times the average of front and back depth. Only its solid part displaces water: bed × (1 − porosity), with porosity 25% for sand and 20% for gravel from the USGS table (USGS⁷). Hardscape displaces its full volume.

CO₂

CO₂ (ppm) = 3 × KH (dKH) × 10^{7 − pH}, the relation behind the Krib chart (The Krib (Chuck Gadd's CO2/pH/KH table)⁸). Solving for pH gives the target pH: 7 − log₁₀(CO₂ ÷ (3 × KH)). The 15–25 mg/L range and the 30 mg/L caution are the Krib table's; the 20–30 ppm target is from the EI guide (Barr Report forum⁹); drop-checker readings are from Hoppy's Barr Report post (Barr Report forum (Hoppy)¹⁰) and Green Aqua (Green Aqua¹¹).

Dosing schedules

EI amounts are the Barr Report EI light table as written (Barr Report forum⁹), also published by NilocG (NilocG Aquatics¹²). Teaspoons become grams using a figure you can change; the 6 g default and the weighed values come from a UK Aquatic Plant Society thread (UK Aquatic Plant Society forum¹³). PPS-Pro uses Green Leaf Aquariums' recipe and doses (Green Leaf Aquariums¹⁴).

Build-up: with a weekly dose D and a weekly change of a fraction f, the level just before a change tends to D ÷ f, assuming no uptake. The chart steps through eight weeks of doses and changes.

Product labels

Liquid fertilizer and remineralizer doses are the makers' directions, scaled in a straight line to your volume and target: Seachem¹⁵, Tropica Premium¹⁶, Tropica Specialised¹⁷, Aquarium Co-op¹⁸, NilocG Aquatics¹⁹, 2Hr Aquarist²⁰, Seachem Equilibrium²¹, SaltyShrimp²², Dennerle²³. Liquid ppm assume a density of 1.00 g/mL because no label states one; real solutions are denser, so actual ppm run somewhat higher.

Light

PAR ranges and photoperiods are 2Hr Aquarist's (2Hr Aquarist on PAR²⁴, on light hours²⁵, on PAR tables²⁶). DLI = PAR × hours × 3,600 ÷ 1,000,000 (Virginia Cooperative Extension²⁷).

Species

Size, minimum base, temperature, pH, GH and group size are from each species' Seriously Fish profile (Seriously Fish²⁸). Shrimp size is from UF/IFAS (University of Florida IFAS Extension²⁹).

Sourcing rules

• A figure appears only if we can link where it was published, or if it is computed from such figures. Computed values show their working.
• Inputs that are just a starting point are marked example.
• Where sources disagree, the page names each one and its figure.
• Where we found no source, we say so and leave the number out. There's no bubble-count-to-ppm figure and no fish-per-gallon rule here for that reason.
• Each source is listed with the date we read it. Labels and pages change; if you find a difference, tell us at hello@mosspearl.com.