IceCap All-In-One Cube Aquarium, 20-Gallon

Handmade 20-Gallon Cube AIO with Low-Iron Glass and Three-Chamber Filtration

The IceCap 20 Gallon Cube AIO Rimless Glass Aquarium is a handmade all-in-one system that integrates a three-chamber filtration compartment directly into the back of the tank, eliminating the need for an external sump or hang-on-back filter in a 20-gallon build. The front and side viewing panels use 6mm Low-Iron glass — a material that removes the greenish tint present in standard aquarium glass and renders the colors of fish, coral, and live rock closer to their actual appearance. IceCap includes Low-Iron glass on the side panels as well as the front, which matters in a cube format where side-angle viewing is part of the daily experience.

The tank measures 18 x 18 x 16 inches — a nearly cubic footprint that delivers the proportionally taller viewing profile that reef builders and aquascapers choose cube tanks for. The three-chamber back section divides into a pre-filter chamber (3.2 inches wide), a main filter chamber (8.2 inches wide), and a pump chamber (3.75 inches wide). The filter chamber's width of 8.2 inches is generous for an AIO tank this size: it accommodates a nano protein skimmer, heater, ATO probe, and filter media simultaneously without stacking constraints. A Mesh 200M filter sock is included for the pre-filter chamber, and a 211 GPH (~800 LPH) return pump is included, making the tank ready to plumb and fill from the start. A self-leveling mat comes pre-installed on the base.

Key Features:

• Handmade all-in-one rimless glass aquarium; 20-gallon cube format (18 x 18 x 16 in)
• 6mm Low-Iron glass on front AND side panels for true-color viewing from all angles
• Three-chamber AIO filtration: pre-filter (3.2 in), filter chamber (8.2 in), pump chamber (3.75 in)
• 8.2-inch filter chamber accommodates a protein skimmer, heater, ATO probe, and media in one compartment
• Included Mesh 200M filter sock for the pre-filter chamber
• Included 211 GPH (~800 LPH) return pump — no separate pump purchase required
• Included plumbing for ready-to-connect AIO setup
• Self-leveling mat pre-installed on the base
• Rimless construction for unobstructed top-down and open-top builds
• Freight shipping; arrives protected for glass transport
• 1-year limited warranty (see warranty details for modifications and stand exclusions)

Ideal For:

• Reef and marine hobbyists starting or upgrading to a 20-gallon saltwater system who want a complete AIO platform that does not require a separate sump, stand plumbing, or external filtration equipment to run
• Aquascapers and planted tank builders who want the cube format's equal-width depth and taller vertical profile for a Nature Aquarium-style layout where foreground and background planting depth matters
• Hobbyists stepping up from a 10-gallon nano system who want a meaningful volume increase and display upgrade while keeping the desk or countertop footprint manageable at an 18x18-inch base

Pro Tips:

• Never Turn On or Cycle Your Return Pump While the Rear Chambers Are Dry. Submersible aquarium pumps depend on water to lubricate their ceramic shafts and cool the magnetic impellers. If you turn on the return pump while the rear chamber is dry, it can quickly overheat and damage the motor or cause electrical problems. Always fill both the main viewing area and the rear filtration zones with water before powering on the system.
• Rinse the Mechanical Filter Sock at Least Twice a Week under Fresh Water. Because a 20-gallon nano tank holds a small, highly concentrated volume of water, trapped food particles and organic fish waste caught inside your 200-micron mesh filter sock will decay quickly. If left uncleaned, this waste breaks down rapidly, spiking your nitrate and phosphate readings. To prevent nuisance hair algae outbreaks, pull the filter sock out every 3 to 4 days, flip it inside out under a warm kitchen sink tap to flush debris, then pop it back into place.
• Use the Middle Rear Filter Chamber for Your Heater and Auto Top-Off Sensors. When organizing your rear support gear, place your glass heater element and automatic top-off (ATO) water level sensors directly inside Chamber 2 (the center chamber). The water levels in Chambers 1 and 2 remain fixed due to the glass baffle layout, while the water level in Chamber 3 (the pump room) drops continuously due to everyday evaporation in the room. Placing your heater or sensors in the center chamber protects your heating element from running dry and prevents your ATO from accidentally dumping too much freshwater into the tank.