Quick dirty ropes

Just wondering if anyone has isolated a specific cause that makes ropes pick up aluminum dirt quickly. The last two new ropes I've had have both gotten lots of black aluminum residue on them within the first weekend of their use, and I've been trying to figure out exactly what the culprit is. I've tried different anchor draws, but that didn't help. I'm thinking ATC or Grigri. Anyone else have this problem or have any suggestions for keeping a new rope clean longer?

If you are using them primarily to toprope, invest in two steel locking carabiners for the anchor.

Tube devices with alluminun biners. Top roping through aluminum biners. Dirt and grit in the sheath, cleaner you keep the rope the less it abrades biners.

Hmm yeah we're mosty leading on it, and start with a new rope and used aluminum ATC/locker and aluminum biners on the anchor. I guess it's got to be one of those two things.