SJ-CMPS1 Dual-Chamber Tumbling Composter Sun Joe® SJ-CMPS1 Dual-Chamber Tumbling Composter | Product Guide Turn kitchen scraps and yard waste into nutrient-rich compost.The Sun Joe® SJ-CMPS1 Dual-Chamber Tumbling Composter is an all-season outdoor composter with a 2-gallon / 160 L capacity, two sliding chambers, 360° drum rotation, 16 built-in vents, a polypropylene drum, and a powder-coated steel frame. The dual-chamber design lets one side cure while the other side stays active for continuous composting.♻️ Reduce Waste 🌱 Garden Composting ☀️ Weatherproof Outdoor BuildMeet the SJ-CMPS1 Key Components🟩Drum panels — 7 polypropylene panels that form the tumbling barrel🚪Door panel + 2 doors — sliding doors for loading compost materials and emptying finished compost↔️Divider — separates the drum into two composting chambers🌀360° rotating drum — tumbles materials for mixing and aeration💨16 vents — promote airflow to support faster decomposition🧱Powder-coated steel frame — supports the drum for outdoor use🧷Axle + PVC caps — allow the drum to rotate on the frame🔩Assembly hardware — includes M5x10 and M6x55 screws and nutsTechnical SpecificationsSpecificationSJ-CMPS1Product TypeDual-chamber outdoor tumbling composterBest UseAll-purpose composting of biodegradable garden and kitchen wasteCapacity42 gal / 160 LWeight Capacity330 lbs / 150 kgChambers2Drum Rotation360°Vents16WeatherproofYesDrum MaterialPolypropyleneFrame MaterialPowder-coated steelDrum Height23.5 in. / 60 cmTotal Height37 in. / 94 cmTotal Width26 in. / 66 cmProduct Length22.5 in.Net Weight14.3 lbs / 6.5 kgCompost TimeApproximately 2–10 weeks depending on material and temperatureWarranty2-year limited warrantyWhat's in the BoxIncluded ItemSJ-CMPS1Side panels✔ 2 includedDrum panels✔ 7 includedDoor panel and sliding doors✔ door panel + 2 doorsDivider✔Axle✔PVC axle caps✔ 2 includedA-frame tube sections✔ 2 includedRight angled tube section A✔ 2 includedRight angled tube section B✔ 2 includedM5x10 machine screws and nuts✔ 56 sets includedM6x55 machine screws and nuts✔ 2 sets includedManual✔Before You Assemble or Compost🚫 Do not overload the composter. The maximum weight capacity is 330 lbs / 150 kg. Do not climb in, on, or around the composter.⚠️ Keep hands and loose clothing away when rotating the drum. Keep children and small pets away from the composter during use.🧰 Assemble on level ground. Wear safety glasses during assembly and do not overtighten screws, as overtightening may damage the plastic panels.❄️ Do not rotate the composter with frozen material inside. Wait until the material is fully thawed before tumbling to help avoid drum damage.Assembly Overview📌 Before starting: Choose a level location, remove all parts from the packaging, and confirm all listed carton contents are present.1Door PanelAttach to side panels.›2Drum PanelsInstall panels around drum.›3DividerSlide into inside grooves.›4FrameSnap tube sections together.Attach the door panelAttach the door panel to the two drum side panels using 4 M5x10 machine screws and nuts.Install the first drum panelsInstall one drum panel under the door panel using 7 M5x10 machine screws and nuts. Repeat for two additional drum panels.Insert the dividerAfter installing the six panels, insert the divider between the grooves on the inside face of the drum panels.Complete the drumInstall the remaining drum panels to complete the composter drum, then insert the two doors onto the door panel.Install the axlePress-fit both PVC axle caps on either side of the axle, then slide the axle through the composter drum so it protrudes from both side panels.Assemble the frameSnap the frame tube sections together using the spring-loaded push buttons. The frame tube sections require no screws for this step.Mount the drum to the frameSecure both sides of the axle and frame together using the two M6x55 machine screws and nuts.What to Compost♻️ Best mix: The composter works best with a 2 parts geen to 1 part brown ratio. Greens are moist nitrogen-rich materials, while browns are dry carbon-rich materials.Material TypeExamplesGreens — 2 partsRaw vegetables, plants, fruit scraps, grass clippingsBrowns — 1 partLeaves, twigs, hay, straw, egg shells, coffee groundsDo Not CompostMeat, bones, cheese, plastic, trash, poisonous plantsHow to CompostChoose the right locationPlace the composter on a flat surface with direct sunlight and enough room for the drum to rotate fully.Add compost materialsSlide open one door and add biodegradable materials into one chamber. Keep the 2:1 greens-to-browns ratio in mind.Tumble regularlyClose the door and tumble the drum 5–10 times. Repeat every 2–3 days and every time new material is added.Use the second chamberOnce one side is full, allow it to decompose and start adding new material to the other side. Each chamber works independently.Check if compost is readyFinished compost should look dark brown, feel crumbly, and smell like rich earth instead of rotting vegetables.Empty the composterPlace a tarp or plastic sheet under the composter, rotate the doors downward, slide the door open, and let finished compost fall onto the tarp.Compost Timing GuideAmbient TemperatureApproximate Time75°F / 25°CApproximately 55 days85°F / 30°CApproximately 40 days95°F / 35°CApproximately 35 daysComposting Tips1Keep the 2:1 ratioUse 2 parts greens to 1 part browns. Too many greens may cause odor; too many browns may slow decomposition.2Cut materials smallerSmaller shredded materials decompose faster. Cut kitchen scraps into small pieces and run a mower over leaves if needed.3Check warmth after 2–3 daysIf the compost feels warm to the touch, beneficial organisms are active and breaking down the material.4Moisture should feel like a damp spongeIf the compost feels dry, add a small amount of water and tumble. Avoid adding too much water at once.Using Finished Compost1Sift for fine compostFinished compost may contain both fine and coarse material. Sift for a finer blend for flower pots.2Use coarse material outdoorsUse coarser finished compost as top-dressing for outdoor garden beds or till it directly into the garden.3Save some as starterReserve a small amount of finished compost as a starter for the next batch or to reactivate a batch that slowed too quickly.Care + Relocation⚠️ Remove the drum from the frame before relocating the composter. Move the composter only when safe to do so and avoid dragging or forcing the assembled unit.🚪 Remove the doors before emptying compost. Use care with sharp objects when removing compost to avoid damaging the drum.Troubleshooting GuideUse these quick checks for common SJ-CMPS1 composting, odor, pest, and drum rotation concerns.🌡️ Compost Does Not Heat UpPossible CausesMix is too wet or too dryNot enough nitrogen-rich green materialNot tumbled frequently enoughCold temperature or chamber is nearly emptySolutionsAdd dry brown materials if the mix is too wetSprinkle a small amount of water if the mix is too dryAdd greens such as grass clippings or fruit and vegetable scrapsTumble 5–10 times every 2–3 daysContinue adding material until the chamber is at least half full⏳ Compost Takes Longer Than 10 WeeksPossible CausesMaterials are not shredded small enoughIncorrect green-to-brown ratioAmbient temperature is too lowSolutionsChop or shred materials before addingMaintain the 2:1 greens-to-browns ratioPlace the composter in direct sunlight💧 Compost Too Wet or Too DryPossible CausesExcess wet green materialRain entering through ventsInsufficient moistureSolutionsAdd dry brown materials and tumble if waterloggedCheck all 16 vent covers are properly seatedAdd water lightly and tumble if too dryCompost should feel like a damp sponge👃 Odor IssuesPossible CausesMix is too wetNot enough oxygenFresh kitchen scraps exposed on topSolutionsAdd dry brown materials to absorb excess moistureTumble 5–10 times and briefly open the door for air circulationBury fresh scraps under a layer of dry brown materialTumble after every addition🐭 Pests or InsectsPossible CausesMeat, bones, dairy, or fatty foods are insideKitchen scraps are exposedMix is too dry or not tumbled regularlySolutionsRemove meat, bones, dairy, and oily foods immediatelyMake sure sliding doors are fully closed after each useCover scraps with dry brown materialAdd water and tumble to disrupt ants if the mix is too dry🔄 Drum Difficult to RotatePossible CausesComposter is overloadedFrozen material inside the drumAxle caps shifted or unseatedSolutionsDo not exceed 330 lbs / 150 kgRemove material if the drum will not turn freelyDo not rotate when material is frozen; wait until thawedInspect and reseat PVC axle caps⚖️ Drum Wobbles or Is UnsteadyPossible CausesComposter is not on level groundFrame push-button connections are not fully engagedM6x55 axle bolts are looseSolutionsRelocate the composter to a flat, level surfaceRemove the drum from the frame before movingPress tube sections together until each push button clicksCheck that both M6x55 axle bolts are secureVideo GuideFrequently Asked QuestionsWhat is the SJ-CMPS1 best used for?The SJ-CMPS1 is best used for outdoor composting of biodegradable garden and kitchen waste, such as raw vegetables, plants, fruit scraps, grass clippings, leaves, twigs, hay, straw, egg shells, and coffee grounds.How much material can it hold?It has a 42-gallon / 160 L total capacity and supports up to 330 lbs / 150 kg.Why does it have two chambers?The two chambers let one batch decompose while you continue adding new material to the other side. Each chamber operates independently.How often should I rotate the drum?Tumble the drum 5–10 times every 2–3 days and every time new material is added.What green-to-brown ratio should I use?Use a 2 parts greens to 1 part browns ratio. Greens are moist nitrogen-rich materials, and browns are dry carbon-rich materials.How do I know compost is ready?Finished compost should be dark brown, crumbly, and smell like rich earth instead of rotting vegetables.What should I avoid putting in the composter?Do not add meat, bones, cheese, plastic, trash, poisonous plants, dairy, fatty foods, or oily foods.Can I rotate the drum when the material is frozen?No. Do not rotate the drum when material inside is frozen. Wait until it has fully thawed to help avoid damaging the drum.What should I do if the compost smells bad?Add dry brown materials, tumble 5–10 times, and briefly open the door to improve air circulation. Cover fresh kitchen scraps with dry brown material after each addition.What warranty does it have?The SJ-CMPS1 is backed by a 2-year limited warranty for ordinary household use when purchased from Shop Joe or an authorized seller with proof of purchase. Related articles X20-SAW Series Cordless Handheld Mini Pruning Saw 24V-X2-SB18-TV1 Cordless Snow Blower Bundle What is the reduction ratio of the CJ603E Wood Chipper/Shredder?