Sizu Riatto
Flush Hour · Chapter 9

Flush After Flush

Know when a tub is done. Each flush is about 0.4 of the last, so a geometric series says what the tub can still give, and the stop rule says when a fresh tub would give more.

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Opens on the book's tub. Change any number to your own and press Calculate.

Your flushes, in grams, in order

When to stop

Enter your flushes in grams, then press Calculate.

The formula

  • A geometric sequence multiplies by the same ratio r each step: flush n = a × r^(n − 1), a = the first flush
  • The ratio from your flushes: each flush ÷ the one before; fitted r = (last ÷ first)^(1 ÷ (n − 1)), their geometric mean
  • The sum of the first n flushes = a (1 − rⁿ) ÷ (1 − r)
  • The sum to infinity = a ÷ (1 − r), for r under 1: an upper bound on the tub, never a promise
  • Stop rule, two tests: the pace (the next flush ÷ the days you wait for it) against the tub's average (every gram ÷ days since you spawned it); and a floor, the smallest flush worth the wait. When both say stop, start a new tub
The book's worked example, Chapter 9. The book's flushes are 945, 362, 148 g: ratios 0.383 and 0.409, fitted 0.3957, about 0.4. In all 1,455 g, BE 80.83%. With r = 0.4 the model gives 378 and 151.2 g, three flushes 1,474.2 g, and a sum to infinity of 1,575 g (a BE ceiling of 87.5%). A fourth flush would be about 59.2 g in 14 days, 4.23 g a day, against the tub's 27.45 g a day to day 53, and under a 100 g floor: start a new tub.
Check it. Call your second flush as your first × 0.4 before it comes, then weigh it: it is Check It in Chapter 11.

Honest limits. The ratio 0.4 is one study's average across flushes; tubs, strains and rest between flushes move it. The model is a description of past flushes, not a forecast you can bank: the sum to infinity is a ceiling. The book's tub, its straw and its harvests were worked out on paper from published figures, not grown by us: weigh your own. Prices are illustrative, as seen in November 2026 (US mid prices, with UK beside where they differ), shown without a currency sign; put in your own. No yield or profit is promised. Everything stays in your browser: no sign-up, nothing stored.