Fluval P Series Aquarium Heaters

The Fluval P Series is a line of compact, preset submersible heaters built for nano and small aquariums. Each one holds a steady 76 to 78 F (24 to 26 C) with no dial to fuss over, so you simply submerge it, plug it in, and let it maintain a stable tropical temperature. The shatterproof body is fully submersible and safe for both freshwater and saltwater.

Running a bigger tank? Step up to the adjustable Fluval T Series (15 to 80 gallons) or the premium mirror-glass Fluval M Series, and keep an eye on your water with a digital thermometer.

Features

• Preset 76 to 78 F (24 to 26 C). Factory-calibrated to the tropical community sweet spot, with no dial to bump or recalibrate.
• Shatterproof body. Durable construction resists cracking, so it holds up in busy nano tanks.
• Fully submersible. Mount it vertically or horizontally, completely underwater, using the included suction cups.
• Slim, hideable profile. The compact shape tucks behind decor or into a rear chamber with ease.
• Indicator light. A small amber light shows at a glance when the heater is actively warming.
• Fresh or salt water. Safe for tropical community tanks, bettas, shrimp, and nano reef setups alike.

Choose Your Size

All three hold the same preset 76 to 78 F range. Pick by tank size: match or slightly exceed your aquarium volume for steady heating.

How to Use

Position the heater fully underwater near good flow, ideally close to the filter outlet so heated water circulates evenly. Let it sit for 15 to 30 minutes before plugging in so the internal thermostat matches the water. Because the P Series is preset, there is nothing to adjust; the indicator light cycles on and off as it holds temperature. Always unplug before removing it from the water.

FAQ

Can I change the temperature?
No. The P Series is factory preset to 76 to 78 F, which suits most tropical community fish, bettas, and shrimp. If you need a specific setpoint, choose the adjustable T Series or M Series instead.

Which size do I need?
Match the model to your tank: P10 for up to 3 gallons, P25 for up to 6 gallons, and P50 for up to 15 gallons. In a cold room, size up to the next model.

Is it safe for saltwater?
Yes. Every P Series heater is rated for both freshwater and saltwater aquariums.

Should I use a thermometer?
Yes. A separate thermometer lets you confirm the water is holding in the preset range, which is good practice with any heater.