1. How to find your filter model
To choose a spare part you need the exact filter model; the range name is not enough. Look at the marking on the filter housing or lid and note the full model name with all letters and digits. If the marking is worn, the model is in the filter manual or on the box.
Within one range, parts can differ by model and by production date. With the AquaEL Ultramax, for example, whether a part fits also depends on when the filter was made. So check the production date as well and compare the part's article number with the manufacturer's spare parts catalogue.
A separate guide covers choosing a filter, filter types and the order of the media; this one is only about replacing parts. Choose a part only by the model named in its own description.
2. Sponges and cartridges: PPI and density
Sponge porosity is often given as PPI, pores per inch: the higher the PPI, the finer the pores. An AquaEL Hypermax comes with three sponges: 10 PPI in the prefilter and 20 PPI and 30 PPI in the baskets.
The AquaEL Hypermax Blue 30 PPI is a replacement sponge for the Hypermax 4500 BT, Hypermax Link and Hypermax BT Thermo, and the same sponge comes with these filters. For Ultramax and Maxi Kani external filters there is the AquaEL Foam Cartridge Standard, which according to the manufacturer puts flow first and gives mechanical and biological filtration.
For SunSun HW and LW series filters there is an original set of 3 sponges. Variant 602 fits the HW-602 and LW-602, variant 603 the HW-603 and LW-603.
3. What gets replaced more often
A mechanical sponge collects dirt and clogs over time, while a biological sponge is a surface for bacteria. According to Juwel, the coarse blue bioPlus coarse sponge in a Bioflow filter should be replaced after about 3 months, but never all blue sponges at the same time.
We stock Juwel bioPlus coarse in sizes M (Primo 110, Rio 125/180/240, Lido 120/200), L (Rio 350) and XL (Rio 450). Choose the size by your aquarium's Bioflow filter; the full compatibility table is on the manufacturer's page.
For AquaEL Versamax FZN-1 and FZN-2 filters there are original sponges, 2 per pack. The manufacturer recommends replacing them regularly and rinsing them only in old water drained from the aquarium during a water change. The product text gives no exact interval, so check the filter manual.
4. Gaskets and seals: signs of wear
A gasket keeps the filter housing and lid sealed. A hardened, cracked or deformed gasket is a common cause of leaks. Check the gasket at every service and replace it with the original gasket for your model.
The AquaEL Maxikani gasket set is an original spare part for servicing Maxikani filters and stopping leaks. According to AquaEL, a thin layer of silicone grease helps new seals last longer.
According to OASE, the BioMaster main gasket fits the BioMaster and BioMaster Thermo 250, 350, 600 and 850 as well as the BioMaster² and BioMaster² Thermo. Replacing the gasket seals the housing again without changing larger parts.
5. Rotor and shaft: noise and weak flow
If the filter becomes noisy or the flow weakens, first check whether the sponges and hoses are clogged. If they are clean, the cause may be a worn or damaged rotor or shaft in the pump chamber.
For AquaEL Ultramax 1000, 1500 and 2000 filters made from 01.08.2023 there is a rotor set (part no. 15, art. 132206 in the manufacturer's catalogue). The ceramic FI5 rotor shaft (part no. 16, art. 132205) fits the same filters and the Ultramax BT, and is sold separately. According to the manufacturer, the ceramic shaft helps the filter run almost silently.
The OASE BioMaster rotor comes in variants: one shared rotor for the BioMaster 250 and 350, and separate variants for the BioMaster 600 and BioMaster 850. Choose the variant by the size of your filter.
6. Check valves, hoses and adapters
The AquaEL Check Valve OUT is the outlet check valve for Ultramax filters made from 01.09.2020. Variant 1000/1500 fits the 1000 and 1500, variant 2000 fits the 2000 and the Ultramax BT; in the manufacturer's catalogue the article numbers are 123652 / 123654.
The valves are part of the double ball valve system in the filter lid: when the hoses are disconnected, they close the filter inlet and outlet and the hoses at the same time. If a valve no longer closes, replace it with the variant for your model.
For hoses and adapters, choose only the original part for your filter model. Find the part in the manufacturer's spare parts catalogue and compare the article number before ordering.
Filter lines and the spare parts we carry for them
| Filter line | Spare parts | Which models |
|---|---|---|
| AquaEL Ultramax | Standard cartridge, rotor set, FI5 rotor shaft, check valve OUT | Rotor: 1000/1500/2000 from 01.08.2023; shaft also BT; valve from 01.09.2020 |
| AquaEL Maxi Kani | Standard cartridge, gasket set | Maxi Kani / Maxikani filters |
| AquaEL Hypermax | Sponge 30 PPI | Hypermax 4500 BT, Hypermax Link, Hypermax BT Thermo |
| AquaEL Versamax FZN | Sponges FZN-1 and FZN-2 (2 pcs) | Each sponge only for its own model |
| OASE BioMaster | Main gasket, rotor | Gasket: 250–850, Thermo, BioMaster²; rotor: 250/350, 600, 850 |
| Juwel Bioflow | bioPlus coarse M, L, XL | Size by the aquarium's Bioflow filter |
Checklist
- Note the exact filter model from the housing or the manual.
- For an Ultramax, check the production date.
- Compare the part's article number with the manufacturer's catalogue.
- Check the filter manual for the right sponge porosity (PPI).
- Do not replace all biological sponges at once.
- Replace a hardened, cracked or deformed gasket.
- With noise or weak flow, check the sponges first, then the rotor and shaft.
Products for this guide
Frequently asked questions
Which sponge fits an AquaEL FZN filter?
The FZN-1 sponge fits the Versamax FZN-1 and the FZN-2 sponge fits the Versamax FZN-2; each pack has 2 sponges.
Which spare parts fit the Ultramax BT?
According to the manufacturer, the FI5 rotor shaft and the check valve variant 2000 fit the Ultramax BT. The rotor set lists only the 1000, 1500 and 2000, so for other parts check the manufacturer's catalogue.
How often should a filter sponge be replaced?
According to Juwel, the coarse blue Bioflow sponge is replaced after about 3 months, never all blue sponges at once. For other filters, check the manufacturer's manual.
Where do I find my filter model?
On the marking on the filter housing or lid, in the manual or on the box.
