How To Heat A Stock Tank Pool For Year-Round Enjoyment
Introduction
Stock tank pools have graduated from a budget-friendly DIY hack to a legitimate landscape design staple. I have seen them featured in high-end desert retreats and urban backyards alike, offering a modern, industrial aesthetic that traditional fiberglass spas simply cannot match. However, the biggest limitation of these galvanized tubs is usually their short season of use.
Without a heat source, that beautiful 8-foot tank becomes nothing more than a decorative water feature once the autumn temperatures drop. By integrating a heating system, you transform the vessel into a year-round hot tub or a “tepid pool” perfect for extending your swim season. For plenty of visual inspiration on heating setups and deck integration, check out the Picture Gallery at the end of this blog post.
In this guide, I will walk you through the three primary methods for heating a stock tank, ranging from portable propane units to permanent electric installations. We will also cover the crucial design elements of hiding the mechanical equipment and the non-negotiable safety protocols required when mixing electricity, heat, and metal tanks.
Understanding the Thermodynamics of Metal Tanks
Before we buy a heater, we have to address the vessel itself. Galvanized steel is a conductor, not an insulator. If you pump heat into a bare metal tank during winter, the cold air and ground will pull that heat out almost as fast as you generate it.
To make heating efficient and affordable, you need to slow down that thermal transfer. In my design projects, we never install a heated stock tank without addressing insulation. At a minimum, you should place the tank on a barrier, not directly on concrete or cold earth.
I recommend sitting the tank on a layer of 1-inch rigid foam insulation board cut to the diameter of the tank. This separates the water mass from the ground temperature. For the sidewalls, the most aesthetic solution is cladding the tank in wood or building a surrounding deck, filling the gap with spray foam or batting.
Designer’s Note: The Cover is Mandatory
The vast majority of heat loss happens at the surface of the water through evaporation. You cannot efficiently heat a stock tank without a high-quality cover.
Do not rely on a thin solar bubble cover alone for winter use. You need a rigid foam spa cover or a custom-built insulated lid. In my experience, a good 4-inch tapered foam cover will cut your heating time (and fuel cost) by over 50%.
Method 1: The Propane Tankless Heater System
This is the most common method for DIY stock tank conversions because it is fast, relatively affordable, and does not require hiring an electrician. It utilizes a portable tankless water heater, similar to what you might use for an outdoor camping shower.
The system works on a loop. Water is pulled from the tank by a pump, pushed through the heater where it is warmed by a propane flame, and returned to the tank.
Choosing the Right Heater Size
You need to look at BTUs (British Thermal Units). A standard stock tank holds about 700 gallons of water. To raise that volume by 10 or 15 degrees in a reasonable amount of time, you need power.
Look for a heater rated for at least 30,000 to 60,000 BTUs. Anything smaller will struggle to combat heat loss on a chilly day. A 10-liter per minute (2.64 GPM) unit is a standard size that balances portability with performance.
The Pump Requirement
Tankless heaters have a safety switch that only ignites the flame when water is flowing. If your pump is too weak, the heater won’t turn on. If the pump is too strong, the water moves through the heater too fast to get hot.
I recommend a transfer pump or a filter pump with a flow rate between 300 and 600 gallons per hour (GPH) for the heating loop. If you are using a large sand filter pump for cleaning, you will likely need to install a bypass valve to slow the flow down before it enters the heater.
Safety and Ventilation
Propane heaters emit carbon monoxide. They must be installed outdoors in a well-ventilated area. Never enclose a portable propane heater inside a sealed box or a garage.
Common Mistakes + Fixes
Mistake: Using standard green garden hoses for the hot water return line.
Fix: Hot water coming out of the heater can reach scalding temperatures that melt standard vinyl. Use braided stainless steel washing machine hoses or high-temp silicone tubing for the connection from the heater back to the pool.
Mistake: Placing the propane tank too close to the heater flame.
Fix: Maintain at least 3 to 4 feet of separation between the propane source and the open flame of the heater.
Method 2: The Wood-Fired Coil (Chofu Style)
For clients seeking a rustic, off-grid aesthetic, wood-fired heaters are the ultimate design flex. These systems use a “thermosiphon” principle, meaning they circulate water using heat convection rather than a mechanical pump.
As the water heats up in the coils or jacket of the wood stove, it rises and flows into the top of the tank, pulling cold water from the bottom of the tank into the stove to be heated. It is silent, smells like a campfire, and requires no electricity.
Installation Layout
The wood stove must be placed lower than the water level of the tank for the thermosiphon to work effectively. If your tank is on a deck, the stove should be on the ground.
You will need to cut two ports into the side of the tank: one near the bottom (intake) and one near the top (return). These ports connect to the stove via stainless steel pipes.
Heating Timeframes
This is not an instant process. Wood-fired heaters are slow. For a 700-gallon tank, expect to tend the fire for 3 to 5 hours to take the water from “hose cold” to “hot tub hot.”
I often tell clients to view this as part of the ritual. It is about the experience of preparing the bath, not just jumping in.
Design Integration
A wood stove is a sculptural element. Don’t try to hide it. Place it on a fireproof pad of slate or flagstone.
Ensure you have a designated storage area for dry wood nearby. Wet wood creates smoke and low heat, which will ruin the experience.
Method 3: Electric Immersion or Inline Heating
If you want the convenience of flipping a switch and having the water stay hot automatically, you need an electric system. This is the most expensive route upfront but the easiest to live with daily.
The “Spa Pack” Approach
The most professional way to do this is to install a spa equipment pack. This is a self-contained unit that includes a pump, filter, and electric heater all in one.
These units usually require a dedicated 220-volt electrical circuit installed by a licensed electrician. They are thermostat-controlled, meaning you can set the tank to 102 degrees and walk away.
Immersion Heaters (The Budget Alternative)
For a lower-budget electric option, some people use bucket immersion heaters. These are dropped directly into the water.
Designer’s Note: I rarely recommend immersion heaters for permanent setups. They are unsightly, pose a higher risk of burn if touched, and struggle to heat large volumes of water efficiently. If you must use one, ensure it is removed completely before anyone enters the water.
Critical Safety: Bonding and Grounding
This section is non-negotiable. When you combine electricity, water, and a conductive metal tank, you create a potential electrocution hazard if stray voltage occurs.
Equipotential Bonding
Every metal stock tank pool used for swimming should be bonded. This is different from grounding. Bonding connects the metal tank to the pump motor and the ground around the pool to create an “equipotential grid.”
This ensures that if there is an electrical fault, the voltage doesn’t pass through the swimmer. You will need a copper bonding lug attached to the steel shell of the tank. A
8 solid copper wire should run from this lug to the bonding lug on your pool pump.
GFCI Protection
Every single plug used for your pump, heater, or lights must be plugged into a GFCI (Ground Fault Circuit Interrupter) outlet. If moisture is detected or a short occurs, the power cuts instantly.
Hiding the Ugly Parts: Enclosures and Landscaping
Once the mechanics are sorted, the challenge is making it look good. Propane tanks, hoses, and pumps are visual clutter that ruins the serenity of a design.
The Slatted Equipment Box
I usually design a slatted wood enclosure to house the pump and propane tank. The slats are crucial because they provide airflow and ventilation for the heater while obscuring the view of the equipment.
Dimensions:
- Height: Make it level with the rim of the stock tank (usually 24 inches) to create a seamless visual line.
- Access: The top should be hinged (like a toy chest) or the front panel should be removable for easy maintenance.
- Clearance: Leave at least 12 inches of empty space around the heater inside the box to prevent overheating.
Landscape Screening
If building a box isn’t feasible, use landscaping. Ornamental grasses are excellent for this because they are soft and move with the wind, contrasting the hard metal of the tank.
Plants like Horsetail Reed or Maidengrass grow tall enough to screen equipment but don’t drop heavy leaves into the water. Keep plants at least 18 inches away from any open flame or exhaust vent.
What I’d Do in a Real Project: A Step-by-Step Summary
If a client hired me today to install a heated stock tank, this is the exact configuration I would deploy for the best balance of aesthetics and function:
- Foundation: Level the ground with pea gravel. Lay down 1-inch rigid foam insulation board. Place the tank on top.
- Heat Source: I would choose a 10L portable propane heater for speed, coupled with a dedicated high-flow filter pump.
- Plumbing: I would hard-pipe the connections using PVC painted black (to blend in) rather than using floppy hoses. I would install shut-off valves on both the intake and return lines so the equipment can be serviced without draining the pool.
- Safety: I would hire an electrician to install a GFCI outlet and perform the bonding of the tank shell.
- Finish: I would build a cedar deck platform that wraps halfway around the tank. Underneath the deck is where the pump and tank hide, accessible via a trap door.
Maintenance for Heated Water
Heating water changes the chemistry. Bacteria and algae love warm water. You will need to be more vigilant with your water quality than you are with a cold plunge.
Chlorine vs. Bromine
Chlorine dissipates very quickly in hot water. If you plan to keep the tank hot regularly, Bromine is a more stable sanitizer for high temperatures.
Checking the pH
Heat can cause pH levels to drift. Test your water weekly. If the pH is off, your expensive heater core can corrode, or scale can build up inside the pipes, reducing efficiency.
Drain and Refill
Unlike a 20,000-gallon in-ground pool, a stock tank only holds about 700 gallons. If the chemicals get hard to manage, or the water gets cloudy, don’t fight it. Drain it, scrub it, and refill it. It’s cheap and ensures clean water.
Common Mistakes + Fixes
Mistake: Forgetting to drain the heater during a freeze.
Fix: Even if you heat the pool, the water inside the heater unit itself can freeze and crack the copper pipes if the pump isn’t running. If you aren’t using the system during a deep freeze, disconnect the heater and bring it indoors.
Mistake: Placing the return jet too high.
Fix: If the hot water returns at the surface, it stays at the surface. Install your return jet near the bottom of the tank to encourage thermal mixing.
Mistake: Ignoring the tank coating.
Fix: Galvanized steel eventually reacts with chlorine/bromine (rust). Coat the inside of your tank with an epoxy liner or a rubberized pool paint to prolong its life and make it smoother to the touch.
FAQs
Can I just use a kettle or boil water on the stove to heat it?
No. The volume of water is too great. Boiling pots of water and dumping them in will barely move the thermometer one degree, and the heat will be lost before you can return with the next pot. You need a constant heat source.
How fast will a propane heater work?
With a 60,000 BTU heater, you can expect to raise the temperature of a 700-gallon tank by roughly 10 to 15 degrees Fahrenheit per hour, assuming the tank is covered.
Does the tank get too hot to touch?
The metal sides of the tank will equalize with the water temperature. If the water is 104 degrees, the metal will be 104 degrees. This is hot, but not capable of burning skin instantly. However, the exhaust vent on a propane heater gets extremely hot—keep kids away from that part.
Can I leave the water in the tank all winter?
Yes, if you keep it heated or circulating. If you let it freeze solid, the expansion of the ice can split the seams of the metal tank, causing permanent leaks. If you aren’t heating it, drain it.
Conclusion
Transforming a stock tank into a heated soaking tub is one of the most rewarding weekend projects you can undertake. It reclaims your outdoor space during the dormant months and provides a luxury experience at a fraction of the cost of a traditional hot tub.
Whether you opt for the crackle of a wood-fired coil or the efficiency of a propane heater, the secret to success lies in the details: proper insulation, safe electrical bonding, and thoughtful concealment of the equipment. Plan your layout, respect the chemistry of the water, and you will have a cozy retreat waiting for you regardless of the forecast.
Picture Gallery
