A hot tub thermal blanket floats directly on the water to slow heat loss and evaporation. It can also help keep debris out and reduce the load on your main cover. The right choice depends on your spa’s shape and size, the blanket material, and whether you want a lightweight bubble layer or thicker foam insulation. Here are five options to compare, plus practical advice for choosing and using one.
Table of Contents
Quick Comparison: Best Hot Tub Thermal Blankets
| Product | Size and style | Standout feature | Best for |
|---|---|---|---|
| Angooni 7′ × 7′ Thermal Blanket | 16-mil square bubble cover | Trim-to-fit design | Square spas and thicker bubble material |
| Spatender Floating Thermal Blanket | 6′ × 6′, 3/8-inch closed-cell foam | Foam insulation | Shoppers who prefer a foam layer |
| Gereat 7′ × 7′ Solar Bubble Cover | 16-mil square bubble cover | Listing states a 10-year warranty | Square spas and customizable coverage |
| SummerCool 8-ft Round Bubble Cover | 16-mil round bubble cover | Round, trim-to-fit shape | Round spas and pools |
| Blue Wave 7′ × 8′ Solar Cover | 12-mil rectangular bubble cover | Made for rectangular spas up to 7′ × 8′ | Rectangular spas |
Our Picks: Best Hot Tub Thermal Blanket reviews
Angooni 7′ × 7′: A Thick Bubble Blanket for Square Spas
The Angooni is a 16-mil bubble blanket sized at 7 feet by 7 feet. It floats on the water and can be trimmed with scissors to match your spa’s shape. The brand says it can reduce evaporation by up to 95%; that figure is a product claim, not a guaranteed result for every tub or setup.
Its relatively thick material is a useful distinction from thinner bubble covers. The blanket is intended to sit beneath a hard cover, particularly in winter, and can also help keep leaves and dust out of the water. Angooni recommends laying it flat to relax folds and placing the bubble side down against the water.
This is a sensible pick if your spa is square and close to the listed dimensions, or if you want extra material to trim for a custom fit. It is a lightweight bubble sheet rather than a rigid replacement for a hard cover. The listing describes it as a consumable cover with an expected use of about one to two seasons, so it may not suit shoppers looking for a long-term foam layer.
Pros:
- 16-mil material is thicker than standard 8–12-mil bubble covers, according to the listing.
- Can be cut to fit different spa shapes.
- Designed to reduce evaporation and heat loss.
- Can help block leaves, dust, and other debris.
Cons:
- The listing describes an expected lifespan of about one to two seasons.
- It should be used with a hard cover for winter protection, not as a substitute for one.
Verdict: Choose the Angooni if you want a thick, trim-to-fit bubble blanket for a square spa and are comfortable replacing a consumable cover over time.
Spatender 6′ × 6′: Closed-Cell Foam for a Different Kind of Insulation
Unlike the bubble-sheet options here, the Spatender uses a 3/8-inch layer of high-density closed-cell foam. It is listed at 6 feet by 6 feet and can be cut with scissors after you place it on the water. The foam is designed to float at the surface and help limit evaporation and heat loss.
The brand also describes the blanket as a way to protect a hard cover from chemical damage caused by gases from the water. It can be used in summer or winter, but the product data does not give a percentage for heat retention or evaporation reduction. That makes direct performance comparisons with the bubble blankets difficult.
Consider this option if foam is your preferred material and its dimensions suit your spa. The smaller listed size is a key limitation: measure the water surface before ordering, and confirm that the blanket will provide enough coverage after trimming. Availability can vary, so check the listing before making plans around this model.
Pros:
- Uses 3/8-inch high-density closed-cell foam rather than a thin bubble sheet.
- Can be trimmed to fit.
- Designed for use in summer or winter.
- Intended to help protect the hard cover from chemical exposure.
Cons:
- The listed 6′ × 6′ size may not cover larger spas.
- The product data does not provide a specific evaporation-reduction figure.
Verdict: The Spatender is worth considering if you want a foam blanket and have a spa that fits within its 6-foot-square dimensions.
Gereat 7′ × 7′: A Customizable 16-Mil Cover with a Stated Warranty
The Gereat is a 16-mil PE bubble cover listed at 7 feet by 7 feet. It can be cut to fit an above-ground or in-ground spa, and the listing also describes it for swimming pools. The bubbles are designed to help retain heat while the sheet covers the water surface.
Its product description says it can reduce evaporation by up to 80% and states that the cover comes with a 10-year warranty. Treat both as listing details to verify: actual performance depends on the fit and conditions, and it is wise to check the warranty’s terms and exclusions before buying. The long stated warranty is a notable difference from the Angooni, whose listing describes a much shorter expected service life.
This model may suit you if you have a square spa and want a thick bubble cover with a stated warranty. Since it is designed to be cut, take care to measure before trimming; a close fit helps avoid uncovered areas. The listing makes broad durability claims, but the supplied product information does not explain how warranty coverage applies to wear or chemical exposure.
Pros:
- 16-mil PE bubble material.
- Can be trimmed for different spa and pool shapes.
- Listing states a 10-year warranty; check its terms before purchase.
- Designed to help reduce evaporation, retain heat, and block small debris.
Cons:
- The warranty claim should be confirmed with the seller and its written terms.
- Requires careful measuring and trimming for a close fit.
Verdict: Pick the Gereat if you want a 16-mil square bubble cover and the stated warranty is important to you, provided you verify its coverage first.
SummerCool 8-ft Round: A Trim-to-Fit Option for Round Spas
SummerCool’s blanket is an 8-foot round bubble cover made from 16-mil material. Its round shape gives you a closer starting point for a round spa than a square sheet, and the material can also be cut for other sizes and shapes. The listing says it is suitable for pools, hot tubs, spas, ponds, and similar water features.
The product is designed to help retain water temperature, reduce evaporation, and keep debris such as leaves and pollen out of the water. Its description includes a care warning: use the cover only when chlorine levels are below 2.5 ppm and pH is above 7.2. Follow that guidance and check the full product instructions before use.
This is a practical match if you have a round spa that is close to the listed size and want a thicker bubble blanket. It is less convenient if your spa is square or rectangular and you want a ready-made fit. As with other floating bubble covers, it is not a replacement for a hard cover where one is needed for insulation or protection.
Pros:
- 16-mil material in an 8-foot round shape.
- Can be trimmed for a custom fit.
- Designed to reduce evaporation and help keep debris out.
- Suitable for several types of water features, according to the listing.
Cons:
- Check water chemistry against the stated chlorine and pH limits before use.
- The round starting shape may require more trimming for non-round spas.
Verdict: The SummerCool is a strong shape-specific choice for a round spa, as long as its chemical-use instructions work with your water-care routine.
Blue Wave 7′ × 8′: A Rectangular Solar Cover for Larger Spas
The Blue Wave is a rectangular 12-mil solar bubble cover, sized for spas up to 7 feet by 8 feet. It is thinner than the 16-mil covers in this lineup, but its dimensions are a useful fit for many rectangular spa layouts. The material can be trimmed to match your water surface.
The listing says the cover is designed to reduce evaporation by up to 95%, retain heat, and help keep leaves and bugs out. It also claims the cover can use passive solar energy to warm the water. Solar gain varies with conditions, so think of that as a possible benefit rather than a dependable way to reach a specific temperature.
The product includes a 90-day warranty, according to its description. This may be the right option if you need a rectangular shape and value a simple cover that can be cut to size. If thickness is your top priority, the 16-mil Angooni, Gereat, or SummerCool is a closer match.
Pros:
- Rectangular size fits spas up to 7′ × 8′, according to the listing.
- Can be trimmed for a closer fit.
- Designed to reduce evaporation and keep debris out.
- Listing states a 90-day warranty.
Cons:
- At 12 mil, it is thinner than the 16-mil bubble options here.
- Solar warming depends on conditions and should not be treated as guaranteed heating.
Verdict: Choose the Blue Wave if your spa is rectangular and its listed dimensions fit, especially if you prefer a ready-made rectangular cover over trimming a square one.
How to Choose a Hot Tub Thermal Blanket
Measure the Water Surface, Not Just the Outer Shell
Measure the inside water surface from edge to edge, then compare those dimensions with the blanket. A cover that is too small leaves water exposed, while extra material may need trimming. For round spas, measure the diameter; for square or rectangular tubs, measure both sides. If the blanket is trim-to-fit, leave enough material to cover the surface without folding or bunching.
Choose a Shape That Minimizes Trimming
A round cover is a convenient starting point for a round spa, while a rectangular cover can reduce cutting for a rectangular tub. Square sheets are versatile and can be shaped for many layouts, but trimming takes care. Before cutting, lay the blanket on the water and mark the outline as directed by the manufacturer. Cutting too much is difficult to undo.
Compare Bubble Material with Foam
Bubble blankets are lightweight sheets designed to float on the water. The products in this roundup range from 12 to 16 mil, so check thickness if you are comparing bubble options. The Spatender uses 3/8-inch closed-cell foam instead. Thickness alone does not guarantee a specific energy saving or lifespan, but material type and construction can help you narrow your choices.
Set Realistic Expectations for Heat and Water Savings
A floating blanket can help reduce heat loss and evaporation, but it is not a heater and does not replace a hard cover. Product descriptions may state specific reduction figures; those are manufacturer claims, and results can depend on fit and use. A close fit over the water surface is important. For winter use, check whether the manufacturer recommends pairing the blanket with a hard cover.
Check Water-Care Instructions
Hot tub chemicals and water conditions can affect cover materials. Read the product’s care directions before use, especially if a listing gives specific chlorine or pH limits. The SummerCool listing, for example, specifies chlorine below 2.5 ppm and pH above 7.2. Rinse or clean the blanket as directed, and remove it if the manufacturer advises doing so during chemical treatment.
Consider Expected Lifespan and Warranty Terms
A floating blanket may wear out and need replacement, so consider whether the product description gives an expected service life or warranty. The Angooni listing describes an expected use of about one to two seasons, while the Gereat and Blue Wave listings state warranties. Confirm the written terms, including what is covered and any exclusions, before treating a warranty as a measure of long-term durability.
Use It Alongside the Right Main Cover
A thermal blanket floats on the water and can sit beneath a hard cover, but it does not provide the same function as a rigid or insulated spa cover. If you need protection beyond heat retention—such as a secure barrier or weather protection—keep using the appropriate main cover. Follow the spa and blanket instructions for safe handling and storage.
Frequently Asked Questions
What does a hot tub thermal blanket do?
It floats on the water’s surface to help slow evaporation and heat loss. Many bubble blankets can also help keep small debris out of the tub. A thermal blanket is generally an added layer, not a replacement for a hard cover.
Can I trim a hot tub thermal blanket?
Several options in this roundup are designed to be cut with scissors. Check the product instructions first, then place the blanket on the water and mark the shape before trimming. Measure carefully, since removing too much material can leave part of the water uncovered.
Should a floating blanket go under the hard cover?
Some blankets are intended to be used under a hard cover, and the Angooni listing specifically recommends pairing it with one for winter use. Check your chosen product’s directions and continue using your main cover when needed.
Are bubble blankets and foam blankets the same?
No. Bubble blankets use a sheet with air bubbles, while the Spatender option here uses a 3/8-inch layer of closed-cell foam. They serve a similar floating insulation purpose, but their materials, thickness, handling, and fit are different.
How do I choose between a round and square blanket?
Start with the shape and measurements of your spa’s water surface. A matching shape can reduce trimming, while a square sheet may offer more flexibility for a nonstandard layout. Make sure the blanket covers the full surface after any cuts.
Will a solar blanket heat my hot tub by itself?
A solar blanket may collect warmth from sunlight, but the amount depends on conditions. It is designed to help retain heat and reduce evaporation, not to replace the spa’s heating system or guarantee a particular water temperature.
How long will a hot tub thermal blanket last?
Lifespan depends on the material, use, water conditions, and care. The Angooni listing estimates about one to two seasons, while other product descriptions provide warranty information rather than a specific service-life estimate. Follow care instructions and inspect the blanket for wear.
Final Recommendation
For a square spa, the Angooni stands out for its 16-mil thickness and straightforward trim-to-fit design. The Gereat is another square option if its stated warranty appeals to you and you confirm the terms. Choose the SummerCool for an 8-foot round spa, the Blue Wave for a rectangular spa up to 7′ × 8′, or the Spatender if you prefer a foam blanket and its 6′ × 6′ size fits your tub. In every case, measure first and use the blanket according to its care instructions.
