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Mantis Composters Frequently Asked Questions

Here you will find a list of frequently asked questions about the Mantis line of composters.

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Can I cover my ComposT-Twin during the winter?

Yes, if you are not adding materials to your ComposT-Twin, you may wish to cover it with a composter cover. Check our on-line ordering for the ComposT-Twin Cover.

What type of maintenance does the ComposT-Twin require?

The Mantis ComposT-Twin requires little maintenance. After emptying finished compost from a chamber, rinse the inside thoroughly with a garden hose. Occasionally, check the breather screens in the doors to ensure they are not clogged. At the beginning of each season, lubricate the four axle rod guides with a wheel bearing-type grease, and check all screws and bolts for tightness.

Will the composter work if you only put grass in it?

Yes, you can compost only grass, but not very efficiently. A better mix is 60% brown leaves and 40% green grass. Another good addition to a new compost batch is compost activator, or good garden soil - both of which include the beneficial bacteria that speed up the decomposition process.

Is it OK to have pests in your compost pile?

No, you don't want to have pests in your compost pile. Traditional piles can invite all sorts of unwanted pests. Food scraps, especially meat and fish, can attract rodents. Fruit will often attract bees and wasps. And, some materials will attract birds, especially during nesting times. One of the many advantages of the ComposT-Twin is that it's totally enclosed, virtually eliminating rodents, bees, and birds. So, you can compost more materials without the problems associated with "open" compost piles.

Can I use finished compost all year long?

Well-finished compost can be used at any time, in any season, and in any amount. There is no such thing as too much compost.

What is the best temperature for composting?

Your compost should be between 120° Fahrenheit and 150° Fahrenheit, which will make for speedy composting. If the temperature is lower, the pile will still decay – but more slowly. If the temperature is too high, it may kill the beneficial microorganisms that help break down your compost (compost rarely gets too hot). The Compost Thermometer, available via our on-line shopping, will help you monitor the temperature in your compost chambers.

Can I add all of my grass clippings to the compost chamber?

Never add large quantities of grass clippings to the compost chamber. If they are fresh, the nitrogen ratio will be too high for the pile to decay. If you want to use your grass clippings, add a little at a time and store the rest in garbage bags or in a small pile elsewhere until they turn brown. Then they can be used as a carbon source.

Why should I make compost?

Compost is an efficient way to recycle yard and garden "wastes" into the perfect slow-release fertilizer for your vegetable garden, flower garden and lawn. Compost improves your soil structure; it aerates clay soil for better drainage, and gives body to sandy soil to hold moisture and encourage strong root systems. Follow nature´s example by returning and recycling as much organic matter as possible to the soil.

What is the advantage of two composting chambers for the ComposT-Twin?

You can allow one chamber to "cook" while you continue to add material to the other chamber. With the Mantis ComposT-Twin you´ll always have plenty of finished compost on hand, as well as a place to put compostable materials.

How often do I turn my ComposT-Twin?

Turn your ComposT-Twin once a day to properly aerate the material in the chamber. Make sure to turn at least four complete revolutions of the drum. This action aerates the material in the chamber and fluffs the contents. Proper aeration aids in maintaining proper moisture levels – proper moisture means contents will not develop an ammonia or sulfur-like smell. The mixture should feel like a wrung-out sponge. Use your Moisture Meter to test moisture levels. The reading should be between 4-7. The Moisture Meter is available via our online shopping.

How much material does the Mantis ComposT-Twin hold?

It holds almost 25 cubic feet of raw material – that’s 10 bushels in each chamber. It’s the largest, most convenient composter on the market.

What is the overall size of the Mantis ComposT-Twin?

The approximate assembled size is 65” wide, by 66” high, by 41” deep. It sits a convenient 32” high – for easy loading, unloading, and turning the crank.

How is the ComposT-Twin shipped?

The Mantis ComposT-Twin is shipped via UPS; it will arrive in 3 cartons.

Why does the Back Porch model take 4-6 weeks?

An important factor in making compost in 14 days is the amount of materials being used. Volume helps retain the high temperatures generated by the materials in your ComposTumbler. The high temperatures are what help to rapidly decompose your materials. The Back Porch model is not large enough to hold those high temperatures. It was designed for customers that want the benefits of quick composting (instead of the slow pile method), but only have small amounts of material to use.

Is an activator required?

No. If you have a sufficient supply of high-Nitrogen "green" material (fresh grass, kitchen/yard waste, farm manure...) you will not need to use activator to make compost in 14 days. Our activator works as a replacement source of Nitrogen for times when you don't have an available supply of those items. Our activator has a two year shelf life, so it can be purchased in advance and kept on hand for times when it is needed.

Can I compost in Winter?

Your composting season is effective when the outside temperatures are consistently 40 degrees or higher. During colder months, your ComposTumbler should be emptied and cleaned out. The exception is our Back Porch model. Because of its high-density plastic drum, material can be stored inside it during Winter.

What should I do with materials when my drum is full or not in use?

All materials (except grass) can be stored for future use. They can be stored in bags or a plastic trash can/bucket.

How long will my ComposTumbler last?

All ComposTumbler models have been designed to provide you with many years of compost. Our metal drums are galvanized to provide rust resistance. The frames are tubular steel for strength and support. Plastic parts are made of high-density polyethylene. As with any piece of outdoor equipment, periodic care helps to get the maximum value from your purchase. With your ComposTumbler you will receive easy instructions for keeping your unit in tip-top shape. And for those customers looking for additional protection, we do offer a heavy-duty, weatherproof, vinyl cover for the Original, Compact and ComposT-Twin models.

Which Mantis ComposTumbler is right for me?

The Original model is for those that regularly accumulate 5 or 6 trash bags (up to 168 gallons) of material every couple of weeks. For customers that generate 2-3 trash bags of material regularly (up to 88 gallons), then the Compact model is right for you. The ComposT-Twin is for those who generate 2-3 bags of materials each week, and want a continuous supply of compost. If you accumulate less, or prefer to add small amounts daily, then you should consider our Back Porch model. In other words, select the largest size that you can regularly fill.

Can I order replacement parts Mantis composters?

Replacement parts for Mantis composters can be ordered by phone. Visit our Contact Us page for all details.