IceCap Freshwater ATO Reservoir

Keep Your ATO Running. Keep Your Salinity Stable.

Every saltwater aquarium loses water through evaporation. While the water evaporates, the salt stays behind, causing salinity to slowly rise. An Auto Top Off (ATO) system replaces that evaporated water—but every ATO needs a clean, reliable freshwater source.

The IceCap Freshwater Reservoir is designed specifically for storing RO/DI freshwater for your automatic top-off system. Built from durable acrylic with a fully enclosed design, it helps minimize evaporation while keeping dust and contaminants out of your top-off water. It also includes twin quick-connect fittings, a micro-dosing line, and a built-in float valve for convenient refilling from an RO system (always supervise refilling).

Available in 5, 10, and 15 Gallon sizes, there's an IceCap reservoir to fit nearly any aquarium cabinet or filtration setup.

Why Do You Need an ATO Reservoir?

A dedicated freshwater reservoir helps maintain consistent water levels and stable salinity without the hassle of daily manual top-offs.

Benefits include:

Maintains stable salinity
Reduces daily maintenance
Helps protect pumps from running dry
Keeps RO/DI water clean and protected
Reduces evaporation from stored water
Keeps aquarium cabinets organized
Works with most Auto Top Off systems

Important: This reservoir is intended for fresh RO/DI or distilled water only. Never fill it with saltwater for ATO use.

Features

Premium acrylic construction
Fully enclosed design helps reduce evaporation
Keeps dust and debris out of stored water
Large removable lid for easy filling and cleaning
Twin 1/4" quick-connect fittings
Dedicated micro-dosing line
Integrated RO float valve for convenient filling*
Perfect for Auto Top Off (ATO) systems
Clean, professional appearance inside aquarium stands

*The included float valve should not be relied upon as the sole safety device when filling from an RO system. Never leave the reservoir unattended while filling.

Available Sizes

5 Gallon
10 Gallon
15 Gallon

Choose the size that best fits your aquarium's evaporation rate and available cabinet space.

Perfect For

Saltwater Aquariums
Reef Aquariums
Mixed Reefs
SPS Systems
LPS Systems
Fish Only (FOWLR) Aquariums
Freshwater Aquariums
Planted Aquariums
Turtle Tanks
Paludariums
Terrariums requiring freshwater storage

Pairs Perfectly With the IceCap ATO EZ Automatic Top-Off System

Take the guesswork out of replacing evaporated water by pairing your IceCap Freshwater Reservoir with the IceCap ATO EZ Automatic Top-Off System.

Together, they create a reliable automatic top-off solution that helps:

Maintain stable salinity in saltwater aquariums
Automatically replace evaporated water
Reduce daily maintenance
Protect return pumps from running dry
Keep your aquarium running consistently while you're away

The IceCap Freshwater Reservoir provides a clean source of RO/DI freshwater, while the IceCap ATO EZ automatically replenishes your aquarium as water evaporates—helping create a healthier, more stable environment for fish, corals, turtles, and aquatic plants.

Infinity Tip: For best results, always fill your reservoir with RO/DI or distilled water only. Never use saltwater in an ATO reservoir.

Why Shop With Infinity and Beyond Aquatics?

At Infinity and Beyond Aquatics, we're hobbyists first. We know how important dependable equipment is because we use it ourselves.

When you shop with us you'll receive:

Expert aquarium support before and after your purchase
Carefully packed orders
Fast processing
Competitive pricing
Trusted aquarium brands
Friendly customer service from fellow hobbyists
A small business that genuinely appreciates your support

Whether you're building your first aquarium or upgrading a mature reef, we're here to help every step of the way.

Shipping Information

This item ships via our Medium Shipping service.

To provide the fastest possible delivery, Infinity and Beyond Aquatics ships from multiple fulfillment locations throughout the United States.

If your order contains multiple items, they may arrive in separate packages and on different delivery dates depending on product availability and warehouse location.

Tracking information will be provided for every shipment as it becomes available.