Data retention

Bridge readings stream in every few seconds. Without a cleanup pass, a single tank would accumulate millions of rows a year and the chart would slow to a crawl. ReefCMD summarizes older readings on a fixed schedule so recent data stays second-precise while long-term trends remain visible.
Schedule
Age Resolution What it means
Last 24 hours Full Bridge resolution Every reading the Bridge sends, kept as-is.
24 hours – 7 days 5-minute average Each 5-minute window collapses to one row carrying the average value.
7 – 90 days 1-hour average 5-minute rows roll up into hourly buckets.
Older than 90 days Daily summary (avg + min/max) One row per day with the average plus the high/low envelope, shown as a faint band on the chart.
Dashed lines on the chart
Apex-connected parameters (like temperature) stream continuously, so their lines run all the way to the right edge of the chart. Manually-logged parameters only have a value when you enter one — so after your most recent manual reading, the chart carries that last value forward to today as a dashed, faded line. This keeps every parameter visible out to “now” instead of stopping short, but the dashed style is a reminder that it’s your last known reading — not a new measurement. Log a fresh reading and the solid line catches up.
What stays untouched
Manual readings — the values you type into the log yourself — are never summarized. Same for older non-Bridge data. Only the Bridge’s automated stream goes through the retention schedule above.
Why we do this
At full Bridge resolution, a single tank logs around 6 million rows a year per probe. With the retention schedule, that drops to roughly 30 thousand rows — a ~200× reduction — without losing the long-term trend that the chart actually shows.
Fast charts, lean databases, and no compromise on the recent 24-hour window where second-by-second precision actually matters.
The min/max envelope
For readings older than 90 days, ReefCMD records the highest and lowest values seen each day alongside the daily average. The chart renders that as a soft band around the line so you can see how much the parameter varied even when individual readings have been summarized.
Questions?
Run a research project that needs longer raw windows? Email info@reefcmd.com — we can extend the schedule for individual tanks.