Moving house with a fish tank — save your cycle

Moving an established tank is one of the trickiest things in fishkeeping — your biggest risk isn't the fish or the glass, it's losing the beneficial bacteria that live in your filter media. That colony is your nitrogen cycle, and it can start dying within hours if the media dries out or sits without oxygen. Tell me a bit more about your setup: how big is the tank, what filter are you running, and how long has it been established? Also, how far are you moving — same city or a longer journey?

Good news — a two-year-old Fluval 307 will have a very well-established colony in those foam pads and bio-media, so you've got something worth protecting. For a three-hour move, the single most important thing is keeping the filter media submerged in tank water the entire journey. Fill a sealed bucket or large ziplock bags with your tank water and put the filter media straight in there — never let it air-dry, even for 20 minutes. Keep the fish in separate buckets with a battery-powered air stone. How are you planning to transport everything — do you have a van, or are we working with a car boot?

Keeping the substrate wet is the right instinct — there's bacteria in there too, though the bulk of it lives in your filter. The substrate just needs to stay damp, not fully submerged. Where I'd add an extra layer of protection is dosing with Seachem Stability the moment you get the tank back up and running at the new house. It's a live bacterial supplement that seeds and reinforces the nitrogen cycle — it works even in tanks that are already established, essentially topping up what you've lost during the disruption. Dose it daily for the first week after the move. It's widely available on Amazon UK and costs about £10–15 for a bottle that'll cover you comfortably. Have you tested your water parameters recently, and do you have a test kit for ammonia and nitrite to monitor things in the first week?

Honestly, yes — even with perfect handling, you'll often see a small ammonia or nitrite spike in the first few days. The bacteria population takes a knock from the temperature changes, oxygen fluctuation, and the general stress of the move. With the API kit you'll catch it early, which is what matters. If ammonia starts creeping up, hold off feeding for a day or two and dose Seachem Stability — that combination usually settles things quickly. Avoid doing a gravel vac or water change in the first 48 hours if your readings are stable, as you want to disturb the substrate as little as possible while everything recolonises. Your angelfish will be the most sensitive to any spike, so keep a close eye on their behaviour.

Exactly that. Media submerged in tank water throughout the journey, get the filter running again before you even think about adding fish back, dose Seachem Stability daily for seven days, and test ammonia and nitrite every morning for the first week. If you do those four things with a two-year-old established filter, you've got a very good chance of coming through the move without losing your cycle at all. Good luck with it — and the tetras and corys are forgiving; the angelfish just need stable water and they'll settle in fine.