Reef Tank Ammonia Spike Recovery Guide: Dose Bottled Bacteria
Few moments in the hobby raise a heart rate like a Salifert ammonia kit turning lime green at 2 a.m. A reef ammonia spike usually points to a dead fish wedged behind rockwork, an overdose of food, or a biofilter wiped out by an unrinsed mechanical sock. Whatever the cause, the next 48 hours decide whether your livestock survives, and acting on instinct rather than method is what kills most tanks. This protocol from Gensou Aquascaping at 5 Everton Park covers the exact sequence we use when a customer messages us in panic.
Confirm the Reading Before Reacting
Hobby colour-card kits read false positives when reagent bottles age past two years or when ammonia binders like Prime are still active. Cross-check with a second brand — Salifert and Red Sea rarely fail simultaneously. Anything above 0.25 ppm total ammonia at reef pH 8.1-8.3 is genuinely toxic; below that, the free NH3 fraction is small enough that bottled binders buy time.
Find and Remove the Source
Pull every loose rock, look behind the overflow, lift the sand around burrowing gobies. A decomposing chromis the size of a thumb can push a 200-litre tank past 1 ppm in eight hours. Once the corpse is out, siphon detritus aggressively from the sump and any low-flow corners. Skip feeding entirely for 72 hours.
Dose Bottled Bacteria Immediately
Dr Tim’s One and Only and Fritz TurboStart 900 are the two products with peer-reviewed evidence of reseeding nitrifiers within 24 hours. Dose 60 mL per 200 litres at lights out, then half that dose 24 hours later. Switch off UV sterilisers and ozone reactors during dosing — both kill free-floating bacteria before they colonise. Quality bottled bacteria, RODI top-up reserves and a backup test kit live in the water care and treatment range.
Bind the Toxic Fraction
Seachem Prime at 5 mL per 200 litres binds ammonia into non-toxic ammonium for roughly 48 hours. Re-dose every 24 hours until ammonia reads zero. Prime does not remove ammonia — it parks it — so continued biofilter recovery is still mandatory. Avoid stacking multiple binders; they compete for the same chemistry and confuse test kits.
Water Change Strategy
A 25 per cent change with properly mixed salt at matched temperature and salinity is the single biggest lever. Mix the replacement water at least 12 hours ahead using RODI plus a quality reef salt. Skip aragonite-based pH buffers during the spike — they shift KH too fast and stress already-distressed corals. PUB tap is not an option here; chloramine breaks into more ammonia. A reliable RODI rig and a refractometer from the aquarium equipment range are non-negotiable for reef recovery work.
Livestock Triage
Tangs and angels show ammonia stress first — clamped fins, rapid gill beats, hovering near the surface. Move visibly distressed fish to a hospital tub running an air stone and matched water. SPS corals brown out within hours of a 0.5 ppm exposure, while leathers and zoas often shrug off the same insult. Do not frag stressed colonies; cuts compound the damage.
Carbon, Skimmer and Flow Adjustments
Run a fresh bag of activated carbon to strip dissolved organics released by the dying biofilter. Push the protein skimmer slightly wetter than usual to pull out the foam-prone proteins. Increase circulation toward dead spots — anaerobic pockets in sand or behind rockwork can leach ammonia for days after the original event clears.
Re-test Cadence and Stocking Lock
Test ammonia, nitrite and nitrate every 12 hours for the first three days, then daily for a week. Hold off adding livestock for at least 30 days; a freshly recovered biofilter handles existing bioload but cannot absorb a new fish. Phosphate often climbs after a die-off — a small dose of GFO or lanthanum chloride drops it without crashing alkalinity.
Prevention Going Forward
Quarantine every new fish for 30 days, never feed more than fish consume in two minutes, and keep a small bottle of bacteria starter in the cabinet. A backup heater, an automatic top-off and a power outage alarm prevent most of the cascading failures behind a reef ammonia spike. Singapore’s tropical climate is forgiving for temperature stability but unforgiving for any tank without an ATO during long lights-out periods.
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5 Everton Park #01-34B, Singapore 080005 · Open daily 11am – 8pm
