Where can I find diaphragms for a Koi Pro Blow 100 air pump?

Koi Pro air pumps, distributed by Superfish, are found in many koi ponds in Belgium and France. They are robust, but like all diaphragm pumps, they eventually lose efficiency. And that is where things get complicated: diaphragms for a specific model such as the Blow 100 are not available in DIY stores. The good news is that with the exact reference of your pump, it is almost always possible to find the original part through a specialist retailer.

Step 1: Identify your pump precisely

The product name alone is not enough. Over the years, the same range may have had several versions, with different compression chambers and diaphragms. Turn the pump over or look at its side: the rating plate shows the brand, model, often a product number, and sometimes the year or serial number. Take a sharp photo of it, with the flow rate and electrical power clearly visible. In this category of equipment, the number following the model name generally corresponds to the nominal flow rate in litres of air per minute, which also helps you compare it with other pumps.

If the label is illegible, at least note the pump dimensions and the number of air outlets, and take a photo of the whole unit: this often makes it possible to identify it.

Step 2: Make sure it is actually the diaphragm

Before ordering, rule out causes that do not originate with the pump. Disconnect the hose at the outlet and feel the airflow with your hand. If it is strong, the problem is downstream: clogged diffuser, kinked or crushed hose, blocked manifold, or diffusers positioned too deep for the pump's flow rate. If it is weak while the pump vibrates and hums, the diaphragms or valves are at fault. Also check the air intake filter: when clogged, it reduces the flow just like a worn diaphragm.

Step 3: order the right part

Koi Pro diaphragm kits are not always listed in online stores, including ours, because part numbers change and some parts must be ordered on request from the distributor. The safest approach is therefore to send a photo of the rating plate to a specialist retailer, who will verify the exact part number before any order. Beware of so-called universal diaphragms sold on major platforms: a diameter or mounting point that differs by just a few millimeters is enough to cause leaks, reduced flow, or accelerated wear.

If a complete kit with diaphragms and valves is available, choose it. These parts age together, and opening the pump once is better than twice.

Repair or replace?

On a quality pump in good overall condition, replacing the diaphragms is almost always worthwhile: it is normal maintenance for this type of device. The calculation changes if the housing is cracked, if the electromagnet overheats abnormally, if the pump has taken on water, or if the part is no longer available. In these cases, replacing it with a pump offering equivalent flow is wiser. In a koi pond, do not go several days without aeration while waiting for a part, especially in summer: a backup pump, even a smaller one, protects your fish during the work.

Reinstalling the diaphragms without mistakes

• Always unplug the pump before opening the cover.
• Photograph each step, especially the orientation of the valves.
• Compare the old and new diaphragms before reassembly.
• Tighten the screws gradually in a crisscross pattern, without forcing them.
• Test the airflow at the outlet before reconnecting the circuit.

To extend the life of the new diaphragms, install the pump in a shaded, dry, ventilated location, above water level or with a check valve on the hose.

Read also

For more information: How to repair an air pump or aeration system?.

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Frequently asked questions

— Are Koi Pro diaphragms compatible with other brands?

No, as a general rule. Each manufacturer has its own dimensions and mounts. Only the exact reference for your pump guarantees compatibility.

— Where can I find the reference for my Blow 100 pump?

On the nameplate, underneath or on the side of the housing. Photograph it in full, including the flow and power specifications.

— How long do the diaphragms last?

This depends greatly on the heat, ventilation, and back pressure in the circuit. Checking it every spring and keeping a spare kit on hand is a good habit.

— What should you do while waiting for the part?

Install a backup pump, even a smaller one, especially in summer, reduce feeding, and keep the waterfall running to limit the risk of oxygen shortage.

In summary

• Note the full reference of your Koi Pro Blow 100 before anything else.
• Check that the reduced flow is indeed caused by the diaphragms.
• Order the original part through a specialist dealer, not a universal diaphragm.
• Damaged housing or unavailable part: replace it with a pump with comparable flow.

Last updated: September 29, 2026.