Keeping a nano tank sparkling clean requires special tools and techniques, especially when it comes to maintaining the substrate. These compact aquatic ecosystems, while beautiful to behold, present unique challenges that larger tanks simply don’t have. The limited space means that waste can accumulate quickly, potentially harming your delicate fish and plant life if left unchecked. That’s where a proper small tank gravel cleaner becomes an essential piece of equipment for any serious aquarist working with tanks 20 gallons or smaller.
In the fascinating world of aquarium keeping, gravel cleaners serve as both a maintenance tool and a preventive health measure for your aquatic pets. They work by gently removing debris, uneaten food, and harmful waste products that settle into the substrate without disturbing the beneficial bacteria colonies that form the foundation of your tank’s biofiltration system. For nano tank enthusiasts, choosing the right gravel cleaner isn’t just about convenience—it’s about creating a healthy, thriving environment where your fish and plants can flourish.
Top 10 Small Tank Gravel Cleaner
Detailed Product Reviews
1. Tetra Water Cleaner Gravel Siphon for Aquariums, Easily Clean Freshwater Aquariums
Overview: The Tetra Water Cleaner Gravel Siphon is an essential aquarium maintenance tool designed to efficiently clean freshwater tanks up to 55 gallons. This straightforward device enables hobbyists to perform monthly water changes and remove debris from gravel without disturbing the tank’s ecosystem.
What Makes It Stand Out: The Tetra system distinguishes itself with its user-friendly design that allows users to replace 30% of tank water in just 30 minutes. The package includes everything needed for immediate use: the siphon tube, priming bulb for easy start-up, and a bucket clip to keep hoses in place during operation.
Value for Money: At $8.79, this cleaner offers excellent value for money. It provides all the basic functionality needed for routine aquarium maintenance without the premium price tag of more complex models. The fact that it covers up to 55 gallons further enhances its price-to-performance ratio.
Strengths and Weaknesses: Strengths include its affordability, simple operation, and comprehensive kit that includes essential accessories. The product’s main limitation is its lack of advanced features like adjustable flow rates or specialized attachments for different substrates.
Bottom Line: The Tetra Water Cleaner Gravel Siphon represents an ideal entry-level option for aquarium keepers seeking reliable, no-frills maintenance equipment. It performs its core functions exceptionally well while maintaining an accessible price point.
2. Carefree Fish Aquarium Small Gravel Cleaner 6Ft Hose Silicone Airbag Fish Tank Water Changer Gravel Vacuum Adjustable Length ABS(for 3~8Gal Tank)
Overview: The Carefree Fish Aquarium Small Gravel Cleaner is a versatile 3-in-1 maintenance tool designed specifically for small aquariums between 3-8 gallons, though it can handle tanks up to 50 gallons. This all-in-one system functionally cleans gravel, changes water, and removes debris in a single streamlined process.
What Makes It Stand Out: Its ABS construction with a silicone airbag provides exceptional durability, designed to withstand thousands of compressions without damage. The innovative silicone siphon ball creates stronger pressure with only 3-5 squeezes, taking the frustration out of priming the system.
Value for Money: Priced at $12.99, this model represents a mid-range option that delivers more durability and easier priming than basic competitors. The inclusion of a 6-foot hose and flow control valve justifies the slight premium over simpler models, making it a worthy investment for convenience.
Strengths and Weaknesses: The product’s strengths lie in its compact design yet powerful suction for small tanks, durable construction, and multifunctionality. Weaknesses include its slightly higher price point than basic options and potential limitations for very large aquariums beyond 50 gallons.
Bottom Line: For aquarium keepers with small to medium-sized tanks, the Carefree Fish model offers a reliable, durable solution that simplifies maintenance through intelligent design and quality materials. It’s particularly well-suited for those who value ease of use.
3. Seltomer 4.3ft Fish Tank Cleaner Aquarium Siphon Gravel Vacuum for Aquarium Fish Tank Changing Water Cleaning Gravel and Sand
Overview: The Seltomer 4.3ft Fish Tank Cleaner is an affordable yet effective aquarium maintenance solution designed to handle routine water changes and substrate cleaning. Its straightforward siphon function allows for easy control and convenient removal of fish waste, uneaten food, and turbid water from aquariums.
What Makes It Stand Out: Featuring a 4.3-foot clear, kink-resistant hose, this model provides good reach without compromising durability or flexibility. The innovative design includes a sinkable gravel tube with a detachable filter screen, ensuring fish remain unharmed during operation while effectively preventing substrate from entering the hose.
Value for Money: At $8.88, the Seltomer offers competitive pricing alongside quality construction. The inclusion of a functional filter system and durable hose at this price point represents significant value, particularly for aquarium keepers on a budget seeking reliable performance.
Strengths and Weaknesses: Key strengths include its fish-friendly design, durable construction, and hassle-free operation via the elastic siphon ball. The primary weakness is the limited three-month warranty period, which is shorter than some competitors, indicating potentially lower long-term durability expectations.
Bottom Line: The Seltomer Fish Tank Cleaner delivers reliable performance at an accessible price point, making it an excellent choice for budget-conscious aquarium enthusiasts. Its thoughtful design prioritizes fish safety while maintaining effective cleaning capabilities.
4. hygger Small Gravel Vacuum for Aquarium, Manual 80GPH Aquarium Gravel Cleaner Low Water Level Water Changer Fish Tank Cleaner with Pinch or Grip Run in Seconds Suction Ball Adjustable Length
Overview: The hygger Small Gravel Vacuum represents a premium approach to aquarium maintenance with its 80GPH powerful water flow and ergonomic design. This versatile cleaner adapts to various configurations, making it suitable for small to medium-sized aquariums with options for different cleaning approaches and depths.
What Makes It Stand Out: Its innovative handle-type operation ball conforming to ergonomics sets it apart, offering comfort and multiple operation methods—either by pinching or gripping. The system can operate with water levels as low as 0.8 inches, and its four basic configurations allow customization based on tank size and specific cleaning needs.
Value for Money: Priced at $16.99, this model sits at the higher end of the market, but its premium features justify the investment. The extended length options, multiple attachments, and exceptional water level coverage provide versatility that basic cleaners cannot match, representing long-term value for enthusiastic aquarists.
Strengths and Weaknesses: The cleaner’s strengths include its powerful suction, comprehensive customization options, EVA materials for longevity, and the ability to work at very low water levels. Its main weakness is the higher price point, making it less accessible for casual hobbyists or those with severely limited budgets.
Bottom Line: For serious aquarium enthusiasts willing to invest in quality, the hygger Small Gravel Vacuum offers unmatched versatility and ergonomic advantage. Its adaptability to different tank configurations and superior design make it worth the premium for those seeking professional-grade maintenance without electric components.
5. SunGrow Aquarium Gravel Cleaner Siphon Vacuum, Manual Operation Water Changer Kit, Includes Hose and Priming Bulb for Fish Tank Cleaning (Black, Gravel & Sand Cleaner)
Overview: The SunGrow Aquarium Gravel Cleaner provides a manual water changing solution designed with simplicity and efficiency in mind. The complete kit includes a short nozzle with net, flexible tubing, operation bulb, and discharge hose, offering everything needed for routine maintenance of both freshwater and saltwater aquariums.
What Makes It Stand Out: SunGrow distinguishes itself through its intuitive 2-minute setup and no-spill operation, specifically designed to minimize stress on fish during water changes. The hand controller and operation bulb create efficient water transfer without requiring electrical connections or complex mechanisms.
Value for Money: At $8.20, this model offers one of the most budget-friendly options while maintaining full functionality. The complete basic kit with thoughtful design elements like the short nozzle system for easy placement and a flexible siphon that prevents gravel entry makes it an exceptional value.
Strengths and Weaknesses: The cleaner’s strengths include its ultra-affordable price point, quick setup time, and fish-friendly design. Its limitations include the basic functionality without advanced features like adjustable flow rates or specialized attachments, and the hose length may be insufficient for very large tanks or distant drainage locations.
Bottom Line: The SunGrow Aquarium Gravel Cleaner delivers remarkable simplicity and essential functionality at an unbeatable price point. It’s an ideal option for beginner aquarists or those seeking a reliable, no-frills secondary cleaner for smaller tanks where occasional water changes are all that’s required.
6. Laifoo 5ft Aquarium Siphon Vacuum Cleaner for Fish Tank Cleaning Gravel & Sand
Overview: The Laifoo 5ft Aquarium Siphon Vacuum Cleaner is a practical tool for maintaining clean aquariums by easily removing fish waste, debris, and turbid water. This efficient cleaner features a 5-foot clear and elastic plastic hose that’s durable, kink-resistant, and safe for fish without leaving any peculiar odors.
What Makes It Stand Out: Its standout feature is the user-friendly siphon ball mechanism that requires only pinching to initiate water flow, eliminating the need for complex priming. The gravel tube comes equipped with a detachable filter screen and is sinkable, ensuring minimal disturbance to fish or decorations during cleaning. Additionally, the 3-month warranty with free replacement or refund provides valuable peace of mind.
Value for Money: At just $14.90, this cleaner offers excellent value for money, providing all essential functionality for routine aquarium maintenance at a fraction of the cost of electric alternatives. The durable construction and included warranty further enhance its value proposition, making it an affordable yet reliable solution for both beginner and experienced aquarium owners.
Strengths and Weaknesses: Strengths include its simplicity of use, durable hose construction, effective filtration system, and reasonable price point. The manual operation means no electricity is required. However, the 5-foot length might be limiting for very large tanks, and while durable, the plastic material may not be as heavy-duty as more expensive metal alternatives. Some users might find the manual pumping requires more effort than electric models.
Bottom Line: The Laifoo 5ft Aquarium Siphon Vacuum Cleaner is an excellent budget-friendly option for maintaining smaller to medium-sized aquariums. Its straightforward design, effective filtration, and reasonable price make it a practical choice for regular aquarium maintenance. If you’re looking for an affordable, easy-to-use cleaning solution without electricity, this product offers solid performance and good value for money.
7. QZQ Aquarium Gravel Cleaner [2025 Edition] Vacuum Fish Tank Vacuum Cleaner Tools for Aquarium Water Changer with Aquarium Thermometers Fish Net kit Use for Fish Tank Cleaning Gravel and Sand
![QZQ Aquarium Gravel Cleaner [2025 Edition] Vacuum Fish Tank Vacuum Cleaner Tools for Aquarium Water Changer with Aquarium Thermometers Fish Net kit Use for Fish Tank Cleaning Gravel and Sand](https://m.media-amazon.com/images/I/51S+2N20RtL._SL160_.jpg)
Overview: The QZQ Aquarium Gravel Cleaner [2025 Edition] is a comprehensive multi-functional cleaning kit designed to maintain a pristine aquatic environment. This siphon-based system combines fish tank vacuuming, algae scraping, waste removal, and water changing capabilities all in one package. Its manual press design operates silently without requiring electricity, while the high-quality pressure-resistant air bag ensures strong, efficient siphon pressure.
What Makes It Stand Out: What distinguishes this cleaner is its safety-focused design with a filter net that prevents gravel from causing blockages while protecting small fish and decorative elements. The 2025 edition offers enhanced installation convenience compared to traditional systems, and comes with an impressive array of accessories including multiple water pipes, pump, clips, temperature stickers, fish net, and algae scraper. The package provides a complete cleaning solution rather than just a single tool.
Value for Money: At $18.79, this kit represents excellent value considering its multi-functionality and included accessories. The price is competitive for comprehensive aquarium cleaning systems and only slightly higher than basic models while offering significantly more features and tools. The durability of the components further justifies the cost, making it a worthwhile investment for both novice and experienced aquarium enthusiasts.
Strengths and Weaknesses: Strengths include the multi-functional design, safety features protecting aquatic life, silent operation, comprehensive accessory kit, and responsive customer service. The unit is easy to install and use, especially with the manual press mechanism. However, the multi-piece configuration might be slightly more complex to assemble than simpler siphons, and some users may find the many components require additional storage space. The plastic construction, while durable, might not match the longevity of more premium metal alternatives.
Bottom Line: The QZQ Aquarium Gravel Cleaner [2025 Edition] is an outstanding all-in-one solution for aquarium maintenance that offers exceptional value. The combination of safety features, ease of use, comprehensive accessories, and effective performance makes it ideal for aquarists looking to streamline their cleaning routine. Whether you’re maintaining a small betta tank or a larger aquarium, this versatile kit provides the tools needed for thorough maintenance while protecting your aquatic pets.
8. Aquarium Gravel Cleaner – Naturally Maintain a Healthier Tank, Reducing Fish Waste and Toxins (16 fl oz)
Overview: This Aquarium Gravel Cleaner takes a biological approach to tank maintenance rather than a physical one. Instead of removing debris through suction, it introduces beneficial bacteria that naturally break down fish waste, uneaten food, toxins, and other organic waste products. The 16 fl oz bottle contains a powerful formula designed to improve water quality and clarity while reducing harmful ammonia, nitrite, nitrate, and phosphate levels in both freshwater and saltwater aquariums.
What Makes It Stand Out: What sets this product apart is its biological cleaning method that extends time between water changes and physical cleanings. Many aquarists will appreciate how it corrects for overfeeding issues and works continuously between applications. The concentrated formula treats up to 960 gallons from a single 16 oz bottle, making it one of the most cost-effective biological cleaners on the market. Its versatility for both freshwater and saltwater environments also increases its appeal.
Value for Money: At $15.95 for a 16 oz bottle that treats up to 960 gallons, this product offers exceptional value. Traditional gravel cleaners may require more frequent purchases or higher initial investment for equipment. With weekly application costs of just pennies per gallon, this biological cleaner provides an economical long-term solution for aquarium maintenance. The reduction in frequency of physical cleanings also saves time and effort.
Strengths and Weaknesses: Strengths include the biological cleaning benefit, reduced need for physical cleanings, ease of use (simply add to water), cost-effectiveness per treated gallon, and versatility across aquarium types. However, this product isn’t a complete replacement for physical gravel cleaning, as it doesn’t actually remove large debris. Some users might also notice the effect isn’t immediately visible, requiring consistent application over time. Additionally, it doesn’t address mechanical filtration needs or aesthetic cleaning of algae buildup.
Bottom Line: This biological Aquarium Gravel Cleaner is an excellent supplement to traditional cleaning methods, particularly for aquarists looking to reduce maintenance frequency or those with tanks difficult to physically clean. While it doesn’t replace the need for occasional gravel vacuuming, it significantly improves water quality between cleanings and helps maintain a healthier ecosystem. For its price point and treatment capacity, it represents outstanding value in biological aquarium maintenance.
9. Luigi’s Fish Tank Cleaner – Gravel Pump Vacuum for Aquarium – Hand Siphon Hose to Remove and Change Water or Sand in Minutes – Fish Aquarium Accessories, Supplies & Cleaning Tools
Overview: Luigi’s Fish Tank Cleaner is a compact yet effective manual siphon system designed to streamline water changes and gravel cleaning in aquariums. This hand-operated pump features a sturdy one-way valve that improves suction efficiency, allowing users to clear approximately 30 liters of water in just 5 minutes. The cleaner is specifically engineered to remove fish waste, uneaten food, and toxins that accumulate in the substrate without causing disturbance to the aquarium environment or harming aquatic inhabitants.
What Makes It Stand Out: This product distinguishes itself primarily with its exceptional value proposition – delivering professional-grade cleaning results at a fraction of the cost of more expensive siphons. The built-in filter attachment is thoughtfully designed to protect smaller fish, shrimp, and delicate invertebrates from accidental suction. Additionally, the convenient hand pump eliminates the need for manual priming, making the cleaning process faster and more efficient than traditional siphon tubes without the complexity of electric models.
Value for Money: Priced at just $12.99, Luigi’s Fish Tank Cleaner represents outstanding value in the aquarium maintenance market. While basic in design, it performs all essential cleaning functions effectively without the premium price tag of branded alternatives. The ability to perform full water changes in minutes with zero fuss or complex setup justifies its low cost. For beginners or budget-conscious aquarists, this cleaner offers an affordable entry point into proper aquarium maintenance without sacrificing functionality.
Strengths and Weaknesses: Strengths include its extremely affordable price, quick water changing capability (30L in 5 minutes), integrated safety filter for small aquatic animals, simple operation with no priming required, and durable construction. However, limitations include the shorter hose length compared to some competitors, which might be insufficient for very large or tall tanks. The plastic construction, while adequate, may not be as durable as higher-end metal alternatives. Some users might also desire more varied attachments for specialized cleaning tasks.
Bottom Line: Luigi’s Fish Tank Cleaner is an exceptional budget-friendly solution for routine aquarium maintenance that delivers impressive performance despite its modest price tag. It strikes an excellent balance between simplicity, efficiency, and value, making it particularly well-suited for beginner aquarists or those with smaller aquariums. If you’re looking for an affordable, reliable way to perform regular water changes and substrate cleaning without investing in expensive equipment, this product offers an outstanding option that doesn’t compromise on essential functionality.
10. AREPK Compact Aquarium Siphon Vacuum and Water Changer Kit with Cleaning Brush. Perfect for Simultaneous Water Changing and Cleaning in Small Fish Tanks. Gravel and Sand Cleaning.
Overview: The AREPK Compact Aquarium Siphon Vacuum and Water Changer Kit is a versatile cleaning solution specifically designed to handle aquarium maintenance efficiently, particularly in smaller tanks. This multi-functional system utilizes siphon technology to perform cleaning, waste removal, and water changes simultaneously. The kit features three independent cleaning heads, including a brush for decorations and a cleaning sponge for tank walls, allowing for comprehensive cleaning during a single maintenance session. Its compact size makes it ideal for tanks under 10 gallons while still being effective for larger aquariums above 10 gallons.
What Makes It Stand Out: What sets this kit apart is its thoughtful design for reaching every corner of the aquarium, including tight spots between rocks, wood, and plants, thanks to the thinner cleaning straw. The unique water tubing ensures efficient water transportation, while the upgraded cleaning heads offer dual functionality. The transparent, fish-friendly materials are both safe and odorless, and the included pipe fixing clamp prevents spills during operation. Additionally, the detachable pump head allows for easy cleaning and unclogging, enhancing long-term usability.
Value for Money: At $17.99, this kit offers good value considering its multi-functional capabilities and specialized design for smaller tanks. While slightly more expensive than some basic siphons, the inclusion of three different cleaning heads and specialized accessories justify the cost. The efficiency of simultaneous cleaning tasks saves time and effort, which has its own value. For owners of nano, betta, or turtle tanks where traditional cleaners might be cumbersome, this compact solution provides specialized functionality that larger, more comprehensive kits cannot match.
Strengths and Weaknesses: Strengths include its specialized design for small tanks, multiple cleaning heads for different tasks, ability to reach tight spaces, transparent tube for visibility, spill prevention clamp, and fish-safe materials. The compact size makes storage easy and perfect for small aquarium environments. However, it may be less efficient for very large tanks due to its compact design, and some users might find the multiple components require more time to set up than simpler siphons. The plastic construction, while durable, might not have the longevity of more premium alternatives.
Bottom Line: The AREPK Compact Aquarium Siphon Vacuum and Water Changer Kit is an excellent choice for owners of smaller aquariums, nano tanks, or betta bowls who need a specialized cleaning solution. Its thoughtful design, multiple cleaning heads, and ability to reach difficult corners make it particularly effective for these specific applications. While it may be overkill for very basic setups or larger tanks, it offers exceptional value for its target audience, providing efficient and comprehensive cleaning in a compact, easy-to-use package. If you’re maintaining a smaller aquatic environment where space efficiency is paramount, this kit represents an outstanding investment in tank maintenance.
The Importance of Proper Tank Maintenance
Why Gravel Cleaning Matters in Nano Tanks
In nano aquariums, every inch of space counts, making gravel cleaning an even more critical part of your maintenance routine. The limited water volume means that waste concentrations can rise quickly, creating toxic ammonia spikes that spell disaster for your fish. Gravel cleaning removes this accumulated detritus before it can decompose and harm your aquatic inhabitants. Without regular cleaning, even the most beautiful nano tank can quickly become a hazardous environment, leading to stressed fish and unhealthy plant growth.
How Gravel Cleaners Work: Understanding the Mechanics
A gravel cleaner functions on a simple yet effective principle: creating a siphon effect that lifts debris from the substrate without removing excessive beneficial materials. Most basic models use gravity to create this siphon, with water flowing through a tube that has a wide opening to gather debris and a narrower opening connected to a hose that carries waste water to a bucket or drain. As water flows through the system, lightweight particles are lifted from the gravel bed, leaving your substrate clean while minimizing disturbance to the beneficial bacteria colony that lives within it.
Types of Gravel Cleaners for Small Tanks
Traditional Gravel Vacuum Options
Traditional gravel vacuums utilize the power of gravity to create a siphon effect, requiring manual initiation by sucking on the tube or filling it with water first. These typically come with a rigid tube or bendable material that allows you to reach all areas of your small tank. Some traditional models feature a priming bulb at the top, making siphon initiation easier without having to put your mouth on the tube. While they require more physical effort to operate, many experienced aquarists prefer these for their simplicity and reliability.
Battery-Powered Small Tank Cleaners
For those seeking more convenience, battery-powered gravel cleaners offer the siphoning action without the manual effort. These compact units typically feature a rechargeable battery and a simple on/off switch, making them easy to use even for those with limited hand strength or mobility. Battery-powered models are particularly useful for nano tanks with deep substrates or for aquarists who find traditional siphons physically taxing. However, they may have limited runtime and require regular charging, so having a manual backup is often recommended.
Electric-Powered Compact Solutions
Electric-powered gravel cleaners represent the top tier in convenience for maintaining small tanks. These plug-in models offer consistent suction power with minimal effort from the aquarist. Most electric models include variable suction control, allowing you to adjust the intensity based on your specific needs and tank size. While they typically represent a larger investment than manual or battery-operated options, their ease of use and effectiveness make them popular choices for both novice and experienced nano tank keepers who perform regular maintenance.
Manual Siphon Systems
Manual siphon systems cater to aquarists who prefer complete control over the cleaning process. These often take the form of a simple tube with a weighted end that allows you to direct water flow precisely where needed. Some manual systems come with a collection attachment that traps debris while allowing cleaner water to return to the tank, reducing water waste. These systems require a bit more skill to operate effectively but offer unparalleled control over which areas of the substrate receive cleaning and the intensity of the cleaning process.
Specialized Nano-Specific Designs
The growing popularity of nano tanks has led to the development of specialized gravel cleaners designed specifically for these small environments. These compact tools feature slender nozzles that can access tight spaces and gentle suction calibrated for small volumes of water. Many nano-specific cleaners include flexible attachments that can reach into the unique geometries of small tanks and aquariums with decorative elements that might block access to larger equipment. These specialized designs often incorporate innovative features like integrated water flow regulators or telescopic handles that make them particularly effective for limited space aquariums.
Key Features to Consider When Choosing a Small Tank Gravel Cleaner
Size and Compatibility with Nano Tanks
When selecting a gravel cleaner for your nano tank, dimensions are paramount. The cleaner must be small enough to navigate the tight spaces of compact aquariums without disturbing decorations, plants, or fragile aquascaping elements. Consider both the width of the cleaning head and the length of the hose or tube. Many nano tank keepers prefer models with slender profiles that can reach between plants and into corners where waste tends to accumulate. Additionally, ensure the cleaner can comfortably fit through the top opening of your aquarium while still allowing room for you to maneuver it effectively.
Suction Power Considerations
The appropriate suction power for your small tank gravel cleaner depends on several factors, including your tank size, substrate type, and livestock. Too much suction can uproot plants, pull fish into the tube, or disturb your aquascape, while too little may not effectively remove debris. Look for models with adjustable suction controls that allow you to fine-tune the cleaning intensity to match your specific needs. For tanks with delicate fish like fry or small invertebrates, gentle suction is essential, while tanks with robust community fish and sandy substrates may handle slightly stronger cleaning action.
Ease of Use and Control
For many aquarists, especially those with physical limitations, the ergonomics of a gravel cleaner can be just as important as its cleaning ability. Consider how the tool feels in your hands, its weight distribution, and the ease with which you can direct it precisely where needed. Some models feature comfortable grips or specially designed handles that reduce fatigue during use. Additional controls like thumb-operated valves that let you start and stop the flow without removing the cleaner from the water can significantly enhance your cleaning experience, particularly in small spaces where precision is key.
Noise Level and Operation
In the confined spaces of a home or office, the noise generated by certain gravel cleaning equipment can be disruptive, especially during quiet hours or in shared living spaces. Traditional siphons can be surprisingly loud when priming and during operation, while electric models often have motor noise. Battery-operated options generally fall somewhere in between. Consider where your tank is located and when you typically perform maintenance when evaluating the noise profile of potential cleaners. For nano tanks in bedrooms or offices, quieter models may be preferable despite potentially higher costs.
Durability and Build Quality
A gravel cleaner represents an investment in the health of your tank ecosystem, so build quality and durability are important considerations. Look for models made from materials that