Q Our recycler says plastic containers must have "a neck" to be recycled. Does that include pill bottles? Also, why do the No. 1 and No. 2 plastics have to have screw-top lids to be recyclable?

A Most communities collect only plastic bottles that are made with polyethylene terapthalate (PET) resin, coded as a No. 1, and high-density polyethylene (HDPE), coded as a No. 2 resin. (These include many types of bottles: water and soda bottles [PET], laundry detergent bottles and milk jugs [HDPE], as well as bottles for shampoo, soap, saline solution, lotion, vitamins, aspirin and more.)

Ninety-seven percent of all plastic bottles are recyclable because they are made with PET or HDPE plastic. However, a few bottles aren't PET or HDPE -- such as prescription bottles -- and they are incompatible with most recycling programs. To help people understand that they cannot recycle these containers, the language "with a neck" or "screw top lids" is used by many recycling programs.

So that excludes yogurt tubs, deli trays and plastic to-go containers, even if they are marked as PET or HDPE. The reason for this is that plastic bottles are "blow-molded," while plastic tubs are "injection-molded." The different additives used in each process mean that the two types of material cannot be mixed during recycling, even though they started with the same basic resins. Don't slip them by, hoping they will be recycled. They are just sorted out and disposed of -- at a cost for the recycling program.

Dianna Kennedy, Eureka Recycling

Toilet's dark matter

Q I am curious to know what the dark black matter is that seems to be collecting in my toilet tank. Corrosion from the metal parts? Mold? If it's mold, I can't understand what it is feeding on, as a tank holds just clean water. Is this black matter dangerous? I have been told not to put chlorine bleach in the tank. Is there another way to get rid of it?

A Black stains in sinks, tubs and laundry tubs could be mold, but I don't think so. It sound more like there is manganese in the water supply. This is especially true if the water also feels greasy.

Manganese often appears with iron, so iron removal treatments will also remove manganese. Have the water analyzed and apply the appropriate iron treatment to the water.

Send your questions to Fixit in care of the Star Tribune, 425 Portland Av. S., Minneapolis, MN 55488, or call 612-673-7032, or e-mail fixit@startribune.com. Past columns are available at www.startribune.com/fixit. Sorry, Fixit cannot supply individual replies.