Chl-a Ladder: bandpass filter in vs out
The same eight Chl-a units ran the same rhodamine-WT ladder twice in 35 L of DI water: on Friday 2026-09-11 with the bandpass filter in place, and on Monday 2026-09-14 with it removed. Three In-Situ AquaTroll sondes shared the tank as an independent reference. Friday’s run has its own live page at Chl-a Ladder.
Setup
Units 500134 500151 500161 500163 500210 500218 50081 50086 (500185 and 500184 are not in either
run). Both runs used firmware tlf-main-notehub_env-v0_1_21 with the same Notehub config: LEDs
32 / 512 / 1024 / 2048, SiPM bias 34.0–48.5 V in 27 steps, 1-minute samples,
20-minute sync. The only change between runs is the filter.
Rung medians use the settled part of each rung, from 10 minutes after the dose (mixing) to the
next dose. “Net” is mon2 at the top bias step minus mon2 at the bottom
(pedestal) step, per LED and sample, as on the Chl-a Ladder page.
Findings
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Per-rung medians: net mon2 at LED 2048 (counts)
Green rows are the sondes’ Chl-a fluorescence (RFU) over the part of each rung they were in the tank; a dash means they were not. On Friday they went in after the 100 ppb dose.
Top of the bias arc vs pedestal at LED 2048, final rung (counts)
Net mon2 at LED 2048, every sample
One line per unit, same y-axis on both runs. Dashed verticals are doses.
Reference sondes: Chl-a fluorescence (RFU, log scale)
Readings of exactly zero are drawn at 0.001 RFU so they show on the log axis. Shaded band = sondes in the tank.