Mechanical-biological filter medium for combined water treatment bioMECH has been cleverly designed: dirt-trapping pockets capture and retain large and small dirt particles. At the same time the subtely designed pore structure provides colonisation for the purification bacteria and thus ensures reliable biological decomposition. The material is pH-neutral and does not contain water hardeners. EHEIM bioMECH is suitable for fresh and marine water, is washable and reusable many times.

Specifications

What this pack is. EHEIM article 2508751. They sell it by weight and we list it by volume: 3,430 g of bioMECH is the 5-litre pack. The smaller sizes in the range are 686 g and 1,372 g.

Function: combined mechanical and biological. EHEIM record bioMECH as biological and as non-absorptive — the dirt-trapping pockets do the mechanical half and the pore structure does the biological half.

Chemistry: pH-neutral, and it contains no water hardeners. That matters if you keep soft-water fish or run a buffered planted substrate, because a medium that quietly raises KH will fight both.

Reusable: yes, many times.

EHEIM do not publish a surface area figure, a pore size or a granule size for bioMECH, so we are not going to print one.

Setup & Use

Where it goes in the stack. EHEIM lay their media out as a sequence the water passes through: EHEIM MECH or MECHpro first, as the coarse pre-filter; then EHEIM FIX as the separating layer between the mechanical and the biological stages; then the biological media, where the bacteria live; and finally EHEIM SYNTH filter wool for the fine polish before the water goes back to the tank. Getting the order right is most of getting filtration right.

bioMECH sits in the biological part of the stack, after the coarse mechanical layer and the separating layer, and before the fine wool. In EHEIM’s own professionel filters it is the middle basket — MECH pro below it, SUBSTRAT pro above it.

Never clean or replace all of the biological media at once. This is EHEIM’s own instruction and it is the single most common way a cycled tank gets broken. Rinse gently, do a part of the bed at a time, and use tank water rather than tap water if you can — the bacterial film is the product here, not the substrate it sits on.

New media needs time. bioMECH does nothing biological on the day it goes in. If you are replacing a bed rather than adding to one, do it in halves several weeks apart and keep testing ammonia and nitrite through the changeover.

Freshness & Storage

Every batch we dispatch carries a minimum of 6 months’ remaining shelf life. Store this product in a cool, dry place away from direct sunlight, with the cap or inner foil closed tightly after each use.

Filter media and substrates carry no manufacturing or expiry date — their working life begins on first contact with water, not on the shelf.

Returns & Replacement

Returns are accepted within 7 days of delivery, provided the item is unused and in its original packaging. Manufacturer-sealed items cannot be returned once the seal is broken, and sale-priced items are not refundable.

If your item arrives defective or damaged, message us on WhatsApp with your order number — or email us, if you would rather — and we will replace it. Approved replacements are delivered within 3 to 5 business days. Transit damage is covered by insurance on every shipment. If tracking shows delivered but nothing reached you, tell us within 72 hours, which is the reporting window Indian couriers allow. Damage caused during installation or use is not covered; replacement spares for such cases are chargeable.

Full terms are on our Cancellation & Returns page.