Experiment 003

Aquasoil ammonia decline

A measured ammonia curve from fresh ADA Amazonia: 8 ppm peak on day 3, zero by day 25.

✓ Completed

Question

How does ammonia from fresh aquasoil decline under a heavy water-change schedule?

Background

Fresh active aquasoil releases ammonia for a period after setup. The standard advice is heavy water changes tapering after a few weeks, but the actual duration varies and is rarely published as a measured curve.

Hypothesis

Ammonia would peak in the first days and decline steadily, reaching zero somewhere around the fourth week under an every-other-day change schedule.

Recorded before measuring, so it can be shown to have been wrong.

Equipment

ADA Amazonia Ver.2 Power Sand

Method

Ammonia is hand-tested on a repeating schedule and logged against every water change, so the decline curve and the change cadence can be read together.

Measurements

Ammonia in ppm, hand-tested
Every water change logged with volume
Dissolved solids logged continuously as a second view of each change

Observations

The peak came on day 3 rather than immediately: 4 ppm on the 4th of July, 8 ppm on the 6th.
The decline was monotonic once it began, and stepped down through distinct plateaus rather than falling smoothly. 4 ppm to the 8th, 2 ppm to the 13th, 1 ppm to the 18th, then 0.5 on the 20th and 0.25 on the 24th.
The first zero was on the 28th of July, day 25, and it was still zero on the 1st of August.
Conductivity moved very little across the same period, holding near 100 ppm, so the water change schedule was being driven by the ammonia test rather than by anything the continuous probe could see.

Result and conclusion

Ammonia from fresh ADA Amazonia Ver.2 peaked at 8 ppm on day 3 and reached zero on day 25, under roughly twenty water changes of about 53% each. Two consecutive zero readings were recorded, on the 28th of July and the 1st of August.

The decline is measured rather than assumed, which is the point of running it: the common advice is heavy changes for a few weeks, and this soil in this tank took twenty-five days to reach zero under that regime. What the curve cannot separate is how much of the fall is the soil exhausting its release and how much is the water changes removing it as fast as it appeared. It describes the outcome of a schedule, not the intrinsic behavior of the substrate, and a slower change cadence would almost certainly have produced a different curve.

Future work

Extend the logged series. Ammonia has been tested since the 1st of August and reported as consistently zero, but those readings are not in the record, so the published curve still ends at two zeros.
Record ammonia at the end of a longer interval rather than mid-schedule, since every reading here was taken under changes every one to three days.
Compare the observed twenty-five days against the published expectation for this soil.