Okay, so I finally caved and bought these MEIMEI mineral balls after seeing them all over fish-keeping forums. The packaging was cute - you get a mix of big and small orange/gray balls that look like aquarium candy.
First impression? My betta immediately started using the larger ones as little lounge chairs! Super adorable to watch him perch on them. The shrimp also seem drawn to them, though I can't tell if they're actually eating anything off the surface.
Now the weird part - about three days in, I noticed my water clarity improved dramatically in my 10-gallon tank. Like, crystal clear when it's normally slightly cloudy. But here's where it gets sketchy...my friend had a HORRIBLE experience where their crawfish nearly died after adding these! They had to do emergency water changes and remove the balls.
Personally, I haven't had issues (yet), but I'm keeping a close eye. The balls do roll around mysteriously at night - either my pleco's throwing a secret bowling party or there's some water current magic happening.
Final verdict? They're pretty and my fish seem to enjoy them, but proceed with caution. Maybe start with just a couple balls and monitor your tank closely before going all-in with the full package.