Loading the Reservoir(Quick/Max)Updated 2 months ago

This guide covers how to load your aF4 correctly — from thawing your food to filling the reservoir and positioning the intake tube. Getting this right is the single biggest factor in reliable, consistent dispensing.

The aF4 reservoir holds up to 200 mL of food slurry — approximately 50 cubes of frozen food with saltwater dilution. The reservoir has mL markings on the side to help you track fill level.

Before you load — dilution water

The type of water you use to dilute the slurry matters significantly. Most frozen food cubes are made with fish food and reverse osmosis water, which means they are low salinity on their own. Topping up with high salinity saltwater compensates for this and creates a slurry that stays pourable, stays fresh longer, and is less likely to freeze solid at colder temperature settings.

Saltwater setups: Use high salinity saltwater from your display tank or freshly mixed saltwater. Aim for 1.026–1.030 SG. This is especially critical on the snowflake setting — freshwater or low salinity dilution at this setting will very likely cause the slurry to freeze solid and prevent feeding.

Freshwater setups: Use RO water. Do not use tap water directly — chlorine and chloramines affect food quality. See our Freshwater Compatibility Guide for more detail.

There is no harm in filling right to the max fill line with dilution water. We actively encourage it — a full reservoir ensures the pump can draw food consistently from the first feed to the last.

See our RSW Technology Guide for the full explanation of why saltwater dilution works the way it does.

Choose your loading method

There are two methods depending on how much time you have and how long you need the food to last.

Quick load method

The fastest way to get food into the unit. Ideal for routine refills. Use temperature setting 2 or higher for quick loads.

Step 1 — Insert the intake tubeInsert the intake tube fully until it seats at the bottom of the reservoir, then pull it back approximately ¼ inch. This is a critical step — see Intake tube positioning below.

Step 2 — Add your food
Remove frozen food cubes from the freezer and allow them to thaw at room temperature or in the refrigerator until they reach a loose slurry consistency. 

Never use a microwave, hot water, or any heat source to thaw food. Heat degrades nutritional value and significantly shortens how long food stays fresh once loaded.

Step 3 — Top off to the max fill line
Add dilution water until the reservoir reaches the max fill line. The reservoir's mL markings make it easy to see how much you're adding. Do not exceed the max fill line.

Max fill method — for maximum quantity

Use this method when you want to maximize the food quantity in the reservoir

Step 1 — Fill the reservoir with cubes
Pack the reservoir with as many frozen food cubes as it can hold.

Step 2 — Cover and thaw in the refrigerator
Cover the reservoir with the lid and place it in the refrigerator. Allow the cubes to thaw slowly — overnight or for at least several hours. Slow cold thawing keeps the food as close to its original frozen temperature as possible, maximising freshness from the moment it goes into the unit.

Thawing at room temperature is fine for the quick load method but will shorten the maximum freshness duration achievable. Refrigerator thawing is required for the full 21-day duration.

Step 3 — Add more food
Once the food from step 2 is thawed, repeat this procedure until the desired quantity of food has been achieved.

Step 4 — Fill with dilution
Top the reservoir off to the max fill line with high salinity saltwater (1.026–1.030 SG). 

For full details on achieving maximum freshness duration see our Food Freshness & Storage Duration Guide.

Intake tube positioning — why it matters

The intake tube must be positioned correctly every single time you load the reservoir. Incorrect positioning is one of the most common causes of dispensing issues.

Correct: Insert the tube fully until it seats at the bottom, then pull it back approximately ¼ inch. This lifts the tip slightly off the base, allowing the pump to draw food slurry freely without obstruction.  It is very important that the tubing is not placed OVER a prong.

Too deep: The tip presses against the base — the pump cannot draw food. Result: clear water or nothing dispensed.

Too loose: The tube floats or shifts during operation. Result: irregular dispensing or missed feeds.

Troubleshooting

Only clear water is dispensing
The intake tube is most likely seated too deep. Remove the reservoir, reposition the tube with the ¼ inch pull-back, and run a test feed.

Food is not dispensing at all
Check that the tube is seated in the reservoir and not kinked or disconnected. See our Food Not Dispensing Guide for a full diagnostic.

Food slurry is too thick to pour|
Add dilution water and mix until the slurry pours freely before loading.

Food is freezing solid
You are likely using low salinity or freshwater dilution on a cold temperature setting. Switch to high salinity saltwater (1.026–1.030 SG) and use temperature setting 2 or higher. See our Temperature Settings Guide.

Reservoir running dry before all food is used
You may be under-filling with dilution. Top up to the max fill line — there is no disadvantage to filling fully.  Also, check to ensure that the tubing has not inadvertently been installed over a prong instead of centered in the middle of them.

Related articles

• RSW Technology — How the aF4 Keeps Food Fresh — why saltwater dilution works
• Food Freshness & Storage Duration Guide — maximising how long food stays fresh
• Compatible Foods & Brands Guide — which foods work best
• Sheet Food Preparation Guide — preparing krill, clam, squid, and other large particle foods
• Temperature Settings Guide — choosing the right temperature
• Food Not Dispensing Guide — troubleshooting dispensing issues

Questions about loading the reservoir? Submit a support ticket and our team will help.