What makes a guppy change different
Guppies are small, active, and often kept in planted tanks where babies hide among leaves and floating roots. A water change that would be trivial in a larger fish's tank can accidentally siphon up a fry, tear a delicate tail with a strong refill current, or startle the whole group into jumping. The goal stays the same as any tank, replacing part of the water to dilute waste, but every step is done more gently and with a quick headcount of the smallest residents before and after.
Prepare the replacement water first
Fill a clean, fish-only bucket with tap water that feels the same temperature as the tank when you dip a clean finger in both. Add conditioner to neutralise chlorine and stir it through. Having the refill ready before you start siphoning means the tank never sits low for long, which matters in a small guppy setup where the water level drops quickly. Lay a towel down, unplug equipment that would run dry, and fit the lid or a cover within reach for the moments your hands are out of the tank.
Siphon slowly and watch for fry
Work the gravel vacuum in short passes over open substrate, and hover it carefully near plant bases where waste collects but fry shelter. If your guppy colony is breeding, stretch a piece of clean fine mesh or stocking over the siphon intake and secure it, trading a little suction for the certainty that no baby gets pulled into the bucket. Even with a guard, check the bucket before you empty it; a rescued fry can be netted or cupped back into the tank. Draw off about a fifth to a quarter of the water, then stop, because guppies do best with modest, frequent refreshes rather than large swings.
Refill like rain, not a waterfall
Pour the conditioned water back in a thin, slow stream over the filter outflow, a rock, or your cupped hand so it spreads instead of drilling into the substrate. A strong pour uproots fine plants, clouds the tank, and can batter a male guppy's flowing tail. Top up to the original line, restart the filter and heater, and watch the fish for a few minutes: normal guppy behaviour is quick exploration and interest in food, while clamped fins and hiding suggest the new water differed too much in temperature.
Keeping the routine light but regular
Because guppies breed readily, stocking creeps upward and waste with it, so a tank that thrived on fortnightly changes may need them weekly as fry grow. Trim plant growth during the same session so dying leaves do not rot between changes, and rinse filter sponges only in removed tank water. Rotating which planted corner gets the careful hover-clean each week keeps the whole guppy bed fresher, and it spreads the disturbance so no single group of fry shelters in churned gravel twice running. Recording the task in KinsLe Care Teams means the person who last changed the guppy water is visible to the whole household, and the finished job carries its time mark for the next helper to see.