Active Aqua
Active Aqua 1 HP Water Chiller
The step-up chiller for DIY builders who tried the 1/2 HP math and live somewhere hot: at $1,499 SRP, the 1HP AACH100HP roughly doubles the cooling headroom for $400 more, which is what it takes to hold a 150-gallon uninsulated stock tank in the low 40s through a Texas or Arizona summer. r/coldplunge's standing advice is to oversize the chiller relative to your tank — an oversized unit cycles less, recovers faster after each plunge, and lives longer — and this is the model that advice usually lands on. Same DIY realities as its smaller sibling: bring your own pump, tubing, and filter; keep it out of the weather; expect hydroponics-grade digital controls rather than an app. For insulated barrels in mild climates it's overkill; for big tanks in hot places it's the difference between a cold plunge and a disappointing cool one.
Specifications
Highlights
Pros
- ✓Enough capacity to hold 150-gallon uninsulated tanks cold through southern summers
- ✓Cycles less and recovers faster than the 1/2 HP on the same tank
- ✓Only $400 over the 1/2 HP for roughly double the cooling
- ✓Same huge DIY community and parts availability as the smaller unit
- ✓Titanium heat exchanger built for continuous duty
Cons
- ✗Still no included pump, filter, or fittings — full DIY loop required
- ✗Not outdoor-rated despite most builds living outside
- ✗Louder and hungrier for power than the 1/2 HP
- ✗Overkill for insulated barrels or mild climates
- ✗1-year warranty on a unit running 24/7
Related plunges
More from Active Aqua →
Active Aqua
Active Aqua 1/2 HP Water Chiller
The beating heart of the classic Reddit build: stock tank + this chiller + a pump and some tubing = a powered plunge for under $1,500 that r/BecomingTheIceman has documented in hundreds of build threads. Originally a hydroponics/aquarium unit, the AACH50HP (SRP $1,099) is rated for 90–172 gallons with 4,020 BTU/hr and a Power Boost mode, and it's proven enough that Cryospring literally built their early product around it. Know what you're signing up for: there's no built-in pump — you supply an inline pump (most builds use a ~800 GPH unit), tubing, bulkheads, and ideally a filter — and it's not weatherproof, so it lives in a garage or under real cover. Expect maintaining high-30s/low-40s temps rather than record-chasing cold, especially in summer heat. The DIY forums have solved every failure mode; that community is half the value.
The other hydroponics-store staple in DIY plunge builds, and the Active Aqua's perennial sparring partner in Reddit comparison threads. The 1/2 HP EcoPlus (model 728707, street price around $1,090, list $1,687) is rated for up to 132 gallons, chills down to a claimed 37°F floor, and runs a pure titanium evaporator with a Japanese compressor in a galvanized steel housing — genuinely commercial-grade guts at hydroponics prices. Builders who choose it over the Active Aqua usually cite the titanium evaporator and the slightly lower street price; those who go the other way cite Active Aqua's larger 90–172 gallon rating and bigger build-thread paper trail. Same DIY rules apply: no pump, no filter, no weatherproofing — you're the systems integrator. For a 100-gallon stock tank in a garage, it's a proven, boring, effective choice, which is exactly the compliment it wants.
Penguin Chillers
Penguin Chillers Cold Therapy Chiller
The chiller r/coldplunge graduates to: purpose-built for cold therapy in Tennessee, with the pump built in — the single biggest quality-of-life difference from the Active Aqua path, since your entire install is two quick-connect hoses. 7,500 BTU/hr pulls tubs to 37°F and holds low-40s effortlessly, it's outdoor-rated above freezing, weighs 49 lbs, and costs roughly $18/month to run. At $1,949.99 it splits the difference between hydroponics units and the $4,000 branded chillers, and owner sentiment is about as good as this category gets — the standing Reddit line is that a Penguin plus any tub embarrasses all-in-ones costing triple. They also sell barrel packages sized for Ice Barrels and a $2,699.99 chiller-plus-tub combo. Quibbles: 1-year warranty, tubing costs extra unless you add the install kit, and true sub-freezing ambient operation is off-label.