Marineland Replacement Bio-Wheel for Eclipse 2, Emperor 280B &400B Filters Parts for Aquarium BIO-Wheel Emperor Assemblies for models PF280B, PF280BD, PF400B, PF400BD, and PFE2, 1 Pack. Replacement of this part should only be done if the bio-wheel will no longer spin or if the wheel is broken or damaged. Discoloration of the pleated Bio-Wheel material is normal and desirable. A slight irregularity in the Bio-Wheels rotation is normal. Rotating at any speed the wheel is working to eliminate toxic ammonia and nitrite.