Use clean water and a soft sponge, as soon as a film of algae hides the graduation. Avoid any household product: whatever stays in pond water leaves traces, and a thermometer stays there all year round.

Floating pond thermometer

Name: Floating pond thermometer
Brand: INTEX
Price: 1400.0 RSD
Availability: InStock

1,400.00 RSD

466.66 RSD × 3 with no fees Klarna.

This 19 cm floating thermometer, graduated in degrees Celsius and Fahrenheit, is made of UV-resistant ABS. Its widened head keeps it upright at the surface.

It can be read from the edge, without putting your hand in the water or opening anything.

Thermometer

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The summary

Its scale: degrees Celsius and degrees Fahrenheit on the same column.
Its material: UV-resistant ABS, so it can stay outdoors all year round.
Where to place it: away from the pump's jet, in a calm, shaded area.
How it arrives: 80 g, 19 cm, together with the rest of your order.

Float graduated in Celsius and Fahrenheit, readable from the edge

A liner pond or an opaque tank offers no glass wall on which to stick a thermometer. This one floats: a widened head keeps it upright at the surface, its 19 cm column stays visible, and you read the temperature as you walk past the pond.

🛟 Read it without bending over

A measurement that forces you to kneel down, roll up a sleeve and plunge your arm in ends up being taken less often, especially in winter, whereas a measurement you can read while walking past gets done every day. The scale shows degrees Celsius and Fahrenheit on the same column, and the UV-resistant ABS body is designed to spend the seasons outdoors, exposed to both sun and rain. Left floating permanently, the thermometer gives you the temperature of the surface water, which is the first to react to a cold night or a day of full sun.

🗓️ Through the seasons

In spring

A rise in water temperature tells you when to start feeding the fish again and restart the biofilter.

In summer

Warming water holds less dissolved oxygen, and the morning reading is the most telling.

In autumn

The switch to a cold-season feed is decided by the water temperature rather than by the date.

In winter

The thermometer, left in the opening kept clear by the anti-freeze, can be read without breaking the ice.

Food, antifreeze and bacteria at the right moment

As long as the water stays between 10 and 25 °C, an all-season food suits your koi and your goldfish. In autumn, the same reading tells you when to put a pond de-icer into service, which keeps a hole open in the ice. In spring, it is again the reading that sets the moment to restart the bacterial colony of the filter.

Koi and goldfish are poikilothermic animals: their body temperature follows that of the water, and their digestion slows down with it. Feeding should therefore be set by the thermometer rather than by the calendar. An all-season food can be given as long as the water stays between 10 and 25 °C; below 10 °C, a winter formula lower in protein is more suitable, and feeding stops entirely below 5 °C at the latest. The guide to feeding your fish in winter details the rations step by step and, as a precaution, advises stopping from 8 °C.

In summer, the same reading helps you keep an eye on oxygen. Freshwater saturated with oxygen holds about 11.3 mg/L at 10 °C, compared with 9.1 mg/L at 20 °C and 7.6 mg/L at 30 °C, while fish consume more oxygen as the water warms up. If your thermometer shows warm water for several days in a row, a dissolved oxygen test tells you whether the aeration in the pond is still sufficient.

🦠 The biofilter and temperature

In an aquaponic system, temperature also governs the nitrifying bacteria, which convert the ammonia excreted by the fish into nitrates that the plants can absorb. Their activity is optimal between 17 and 34 °C, and below 10 °C it can fall by half or more, so a buffer tank or an outdoor tank that cools down in autumn processes less ammonia for the same ration. Your readings then tell you when to cut back on feeding, as explained in the guide to preparing an aquaponic system for autumn.

Technical specifications

The essentials

Graduation: Degrees Celsius and FahrenheitBoth scales on the same column, easy to read from a distance.
Length: 19 cmHigh enough to stay visible from the edge of a pond.
Material: UV-resistant ABSDesigned to stay outdoors all year round, exposed to sun and rain.
Weight: 80 gThe wide head balances it and keeps it upright at the surface.

Installation

Location: Calm, shaded areaKeep it away from the pump's jet, which stirs up water that is not representative.
Support: Discreet clip on the edgeA thin line saves you from searching for it at the far end of the pond in strong wind.

In the box

1 floating pond thermometer, 19 cm long.

Graduation, length, material and weight: values from the manufacturer Intex, taken on 20/09/2026. Dissolved oxygen at saturation: freshwater solubility tables. Nitrifying bacteria activity: FAO aquaponics manual.

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delivery time

80 g for 19 cm: a light parcel that travels easily with the rest of your order. The exact shipping costs and final delivery times are shown in your basket once you have entered your address.