Freshwater Compatibility OverviewUpdated 2 months ago

The aF4 works great in freshwater aquariums. The setup process is the same as a saltwater installation, with two simple adjustments — temperature setting and dilution water. This guide covers everything you need to know to get the best results from your aF4 in a freshwater setup.

Is the aF4 compatible with freshwater?

Yes — fully. The aF4 works with any freshwater aquarium setup regardless of species or tank type. Whether you're keeping tropical community fish, discus, African cichlids, coldwater species, freshwater invertebrates, or a planted tank, the aF4 will work for you.

The hardware, tubing, pump, and solenoid system are identical regardless of whether you're running saltwater or freshwater. The only differences are how you dilute your food and which temperature setting you use.

The two adjustments for freshwater

1. Use RO water for dilution

In a saltwater setup, food is diluted with high salinity saltwater. In a freshwater setup, use RO (reverse osmosis) water instead.

Do not use tap water directly — tap water contains chlorine and chloramines that can affect food quality and may introduce unwanted chemicals into your aquarium. RO water is clean, neutral, and the best choice for freshwater dilution.

If you do not have access to RO water, dechlorinated tap water can be used as an alternative — treat it with a standard dechlorinator before use.

2. Use temperature setting 2 or higher

Freshwater has a higher freezing point than saltwater. This means the slurry is more likely to freeze solid at the colder temperature settings, which can block the intake tube and prevent food from dispensing.

We recommend starting on setting 2 for freshwater setups. This keeps food well within the safe cold storage range while avoiding the freezing issues that can occur at the snowflake setting when using freshwater dilution.

If you experience frozen food in the reservoir at setting 2, move up to setting 3.

For full temperature guidance see our Temperature Settings Guide.

Compatible foods for freshwater

The following foods work reliably in the aF4 for freshwater setups:

• Mysis shrimp — excellent all-round food, works well for most freshwater species
• Brine shrimp — highly reliable, widely accepted by freshwater fish
• Bloodworms — a favourite for many freshwater species, flows well when properly diluted
• Daphnia — small particle size means excellent flow and very consistent dispensing

For a full list of compatible foods and preparation guidance see our Compatible Foods & Brands Guide.

Freshness duration in freshwater

Because RO water has different preservation properties than high salinity saltwater, food freshness duration is shorter in a freshwater setup. We recommend a refill cycle of 5–9 days when using RO water dilution rather than the longer durations achievable with saltwater.

For more detail see our Food Freshness & Storage Duration Guide.

Setting up for freshwater — quick checklist

• Install and position the aF4 as normal — see Placement & Orientation Guide
•  Complete the pre-use rinse using tap water or RO water
•  Set temperature to setting 2 or higher
•  Dilute food with RO water before loading
•  Run a test feed before directing output into the aquarium
•  Plan for a 5–9 day refill cycle

Frequently asked questions

Can I use tap water instead of RO water?
Dechlorinated tap water can be used if RO water is not available. Treat it with a standard dechlorinator before use. However RO water is preferred as it is the cleanest option and least likely to affect food quality.

Will the saltwater residue from the factory affect my freshwater tank
No — the pre-use rinse performed before first use clears the unit thoroughly. By the time you run your first feed cycle the system will contain only the water you have introduced.

Can I switch between freshwater and saltwater use?
Yes, though we recommend running a full Auto-Clean cycle and thorough rinse when switching between freshwater and saltwater setups to avoid cross-contamination.

Related articles

• Temperature Settings Guide — detailed guidance on all 5 temperature settings
• Compatible Foods & Brands Guide — food types and brands that work best
• Slurry Dilution Guide — correct dilution technique for freshwater
• Food Freshness & Storage Duration Guide — how long food stays fresh in a freshwater setup

Questions about using the aF4 in freshwater? Submit a support ticket and our team will help.