Water

Pond chemistry, tested by hand. Colour shows each value against its safe band.

Latest reading

16 August 2026

Ammonia 0 ppm

safe 0–0.25 ppm

Nitrite 0 ppm

safe 0–0.25 ppm

Phosphate 5 ppm

safe 0–1.0 ppm

pH 9

safe 6.5–8.5

Ammonia and nitrite remain steady at 0 ppm. pH is back up to 9, and phosphate is back to 5ppm.

Test photos over time

16 Aug 2026

7 Aug 2026

6 Aug 2026

28 Jul 2026

25 Jul 2026

19 Jul 2026

6 Jul 2026

2 Jul 2026

30 Jun 2026

Ammonia (ppm)

Nitrite (ppm)

Phosphate (ppm)

History

Date	Ammonia	Nitrite	Phosphate	pH	Note
16 Aug 2026	0	0	5	9	Ammonia and nitrite remain steady at 0 ppm. pH is back up to 9, and phosphate is back to 5ppm.
16 Aug 2026	0	0	7.5	9	Ammonia and nitrite remain steady at 0 ppm. pH is back up to 9, and phosphate is sitting somewhere between 5-10 ppm despite the heatwave.
7 Aug 2026	0	0	5	8	pH started to climb again, rebounding to 8 a day after the major water change, likely as alkali continues to leach back into the system. Nitrite processed quickly back down to 0 ppm. Phosphate remains steady at 5 ppm.
6 Aug 2026	0	0.5	5	7	Major manual water change, replacing over half a tonne of water by hand. This caused a distinct drop in pH down to 7 (confirmed with full-range litmus paper alongside a lemon juice sanity check) and a notable climb in phosphate back to 5 ppm due to the orthophosphates added to fresh London tap water. Nitrite saw a temporary spike to 0.5 ppm.
28 Jul 2026	0	0	1	9	Deep-clean day: scrubbed the fountain after a resident complaint about the green look, patched a leaky crack with Milliput, and dosed with flocculant to clear the water. Tested before and after the scrub with barely any change, so only logging the post-scrub reading. Phosphate down sharply from 5 to 1; ammonia and nitrite still zero; pH unmoved at 9. Watching for any knock-on ammonia/nitrite bump from disturbed biofilm, and whether the masonry work nudges pH any further.
25 Jul 2026	0	0	5	9	Nitrogen side fully closed out: ammonia down from 0.25 to zero, nitrite still zero, so the cycle that began on the 15th has finished. Phosphate back up from 1 to 5 after a hose pipe top-up ahead of the ban, London tap water being dosed with orthophosphate. pH still pinned at 9.
19 Jul 2026	0.25	0	1	9	Big improvement across the board despite a full algal bloom. Nitrite cleared to zero and ammonia falling as the cycle catches up; phosphate down to 1 ppm, the lowest yet, after a clear-out of decaying matter. pH still stuck at 9.
15 Jul 2026	2	2	5	9	Ammonia and nitrite both up from zero: the pond is cycling as the water soldier and some hornwort die back and start to decompose. Phosphate still down at 5 since planting. pH unmoved.
6 Jul 2026	0	0	5	9	Phosphate halved four days after planting. Ammonia and nitrite still at zero, nothing decomposing yet.
2 Jul 2026	0	0	10	9	Planting day, tested before the plants went in. Phosphate at the top of the chart.
30 Jun 2026	0	0	10	8	Baseline, before the refill. Readings taken indoors so the pH is the least certain of the four; somewhere between 8 and 9.