Emergency response

How to handle an aquarium leak (immediate action)

Step-by-step response

Minute 0-2: Stop the flowDrain water below the leak level using a siphon or bucket. Lower water 4-6 inches below the leak point so it stops dripping.

Minute 2-15: Save livestockMove fish + invertebrates to an emergency container (5-gallon bucket with tank water + air pump if possible). Net coral/snails into temporary holding.

Minute 15-30: Protect floorsTowels around tank base. If wood floors: lift tank slightly with shims to drain moisture, run a fan for 6 hours.

Hour 1: Diagnose leak sourceFind the leak point - silicone seam (most common), corner crack, hairline crack across glass. Mark with tape. Photograph for warranty claims.

Hour 2: Decide repair or replaceSilicone seam fail: re-silicone (DIY $20, professional $200). Hairline crack across glass: REPLACE TANK. Corner crack: re-silicone may work but tank is structurally compromised.

Day 1: Set up emergency tankUse a spare tank, plastic tote, or cycled QT tank to house livestock for 1-2 weeks. Match parameters to home tank.

Day 7-14: Repair completedAfter silicone cure (full 7 days for new applications), water-test the tank with plain RODI for 48 hours BEFORE moving livestock back.

FAQ

Can you fix a leaking aquarium?

Silicone seam failure: yes, drain the tank, scrape old silicone, apply aquarium-grade silicone (NEVER bathroom silicone - mold inhibitors kill fish), cure 7 days. Cracked glass: replace the tank.

How long does aquarium silicone take to cure?

7 days for full cure. 24 hours for surface dryness. NEVER fill before 7 days.

Is bathroom silicone safe for aquariums?

NO. Bathroom silicone contains mold inhibitors that leach into water and kill fish. Use 100% pure silicone aquarium sealant only.

More emergency guides

Browse all aquarium emergency response guides.

Aquarium-keeping fundamentals

Whatever specific topic brought you here, four fundamentals govern long-term aquarium success: water quality, parameter stability, biological filtration, and species-appropriate husbandry. Skip any one and the others struggle to compensate.

Water quality: ammonia + nitrite at zero, nitrate under 30 ppm freshwater + 10 ppm reef. Test weekly with API or Salifert kits. Use our water parameter checker to score your readings against your tank type.

Parameter stability: stable wrong parameters beat fluctuating ideal parameters. Most fish tolerate a wide pH range if it's stable. Sudden swings of 0.4+ pH or 5+°F kill fish faster than chronic suboptimal values. Use temperature controllers (Inkbird) + automated dosing for consistency.

Biological filtration: the bacterial colony on your filter media + rock + substrate is the engine. Never replace all media at once. Use our filter turnover calculator to size correctly.

Species-appropriate husbandry: research adult size, territoriality, diet, and tankmate compatibility before purchase. Use our tank stocking calculator + compatibility guides.

Frequently asked questions

How long does an aquarium take to set up? 4-6 weeks for full cycling + first stocking. Use our cycle ETA calculator + how long does cycling take.

What's the best aquarium for beginners? 20-gallon long. Big enough for parameter stability, small enough for budget + space. See beginner picks.

How often should I do water changes? 25-30% weekly. See water change frequency Q&A + water change calculator.

Why does my fish keep dying? 5 leading causes: uncycled tank, wrong species pairings, no quarantine, undersized tank, neglected water-change schedule. See full diagnosis.