Food Freshness & Storage DurationUpdated a month ago

The aF4 is capable of keeping frozen fish food fresh for up to 21 days under ideal conditions. This guide explains what those conditions are, what a realistic freshness duration looks like for most users, and how to maximize how long your food stays fresh.

How long does food stay fresh?

Maximum duration: 21 days
Achieving 21 days of freshness is possible but requires strict adherence to all of the conditions listed below. We only recommend attempting maximum duration loading when it is genuinely necessary — for example, during an extended absence or when refilling opportunities are limited.

Optimal duration: 10–14 days
For most users under normal conditions, a realistic and practical freshness duration is 10–14 days. This is a comfortable range that doesn't require perfect conditions and still gives your fish consistently fresh food.

Conditions required for maximum 21-day freshness

All of the following must be met to achieve the full 21-day duration. Failure to meet any one of these conditions will reduce how long the food stays fresh.

1. Food has never exceeded 3°C (37°F)
Once food has warmed above 3°C at any point — during preparation, loading, or storage — the 21-day clock cannot be achieved. Food must remain at or below this temperature from the moment it leaves the freezer to the moment it is loaded into the aF4.

2. High salinity saltwater dilution only
The food must be diluted with high salinity saltwater. Freshwater or low salinity water raises the freezing point of the slurry, reduces the preservation properties of the dilution, and significantly shortens freshness duration. See our Slurry Dilution Guide for correct dilution ratios.

3. Temperature set to setting 1(Snowflake)
The aF4 must be set to the coldest settings to maintain maximum freshness. Setting 1 (snowflake) is required for maximum duration loads. See our Temperature Settings Guide for guidance on which setting works best for your food type.

4. Food loaded as slurry — not frozen solid
Food must be fully thawed to slurry form before loading. Loading partially frozen or solid food introduces temperature variability inside the reservoir and can prevent cubes from ever thawing.

Freshwater users

If you are using the aF4 in a freshwater setup and diluting with freshwater, the maximum 21-day freshness duration does not apply. Freshwater dilution reduces preservation effectiveness. We recommend a shorter refill cycle — typically 5–9 days — when using freshwater dilution.

See our Freshwater Use Guide for more detail.

Tips for maximizing freshness

• Prepare food cold — thaw cubes in the refrigerator rather than at room temperature, and load into the aF4 immediately once slurry consistency is reached
• Use high salinity dilution water — this is the single most important factor after temperature setting
• Keep the lid closed — minimize how long the reservoir lid is open during loading to retain cold temperatures
• Start on setting 2 — for most users setting 2 delivers excellent freshness without the risk of the slurry freezing solid on the snowflake setting
• Don't overfill — loading more food than needed for your refill cycle means food sits longer than necessary

Signs that food may no longer be fresh

• Off or sour smell from the reservoir or output tubing
• Discoloration of the slurry or an oily surface appearance
• Fish showing reduced interest in food at feeding time

If you notice any of these, empty the reservoir, run an Auto-Clean cycle, and reload with fresh food. See our Auto-Clean & Deep Cleaning Guide for full cleaning instructions.

Related articles

• Slurry Dilution Guide — correct dilution ratios for maximum freshness
• Temperature Settings Guide — choosing the right temperature for your setup
• Freshwater Use Guide — freshness duration and settings for freshwater setups
• Auto-Clean & Deep Cleaning Guide — cleaning the unit between reservoir loads

Questions about food freshness? Submit a support ticket and our team will help.