Pool Chemistry Calculators

Pool water chemistry is one connected system, not nine separate ones, and getting it right means understanding the order. Every chemical dose starts with volume — half the gallons means half the dose — so any chart that doesn't ask for your gallons is guessing. From volume the cluster splits into two arcs that meet in a single integrator.

The sanitiser archandles what kills algae and bacteria. Chlorine is the workhorse, but its effective level isn't a flat 3 ppm — it has to be about 7.5 % of your cyanuric-acid reading, because CYA binds chlorine and protects it from UV at the same time. That's the central honesty most clones miss. The salt calculator covers the saltwater dose, and its companion — the salt chlorine generator calculator— sizes the cell that actually turns that salt into chlorine, honest about the wedge generic pages miss (the box rating assumes 24-hour pumping, so on a normal 12-hour schedule the cell rated for your gallons can't keep up). Once you're sizing the cell, the saltwater conversion cost calculator totals what the switch will run you and answers the harder question — when it pays back, with the cell-replacement caveat most pages bury. CYA itself is the stabiliser to size for your sun exposure, with the free-chlorine (FC) cost every target carries surfaced rather than hidden.

The balance arc handles what keeps the water comfortable for skin, plaster, and equipment. pH wants to live between 7.4 and 7.6; total alkalinity is the buffer that holds it there; and calcium hardness protects plaster from etching while preventing scale on heaters. pH and alkalinity move together — drop both with the same acid — and the two calculators are one engine behind two doors, asserted equal on every dose. The calcium page is honest about the form gap (anhydrous CaCl₂ is denser than the dihydrate flake) and honest that no chemical removes calcium; dilution is the only knob.

The two arcs converge at the Langelier Saturation Index. LSI is the integrator — it folds pH, alkalinity, calcium, temperature, and total dissolved solids (TDS) into one number that says whether your water is hungry to dissolve calcium (corrosive, etching plaster and metal) or eager to deposit it (scaling heaters and salt cells). Every clone LSI calculator skips the cyanurate correction — the one that flips a “balanced” verdict to “corrosive” when CYA is high. We don't.

When sanitation slips far enough that even an LSI-balanced pool goes green, the shock calculatorhandles triage. The SLAM target (Shock Level And Maintain) is 40 % of your CYA reading for algae, or 10 × combined chlorine for chloramines. Below about 7.5 % × CYA the water has no available chlorine, and the honest answer is to drain and refill rather than chase a number that won't move.