I'm currently using bio powder, about 1/3 of the recommended amount.
I've got some new hemp inserts, which were washed a couple of times then I put them in the machine without powder for a good few washes. Even on the second cycle without powder the water still had quite a lot of suds in it.
Does that suggest I'm using too much powder?
I do have a bit of powder build up in the detergent drawer. I've not noticed any problems with my normal nappies, although I did do a strip wash recently. I have extremely hard water so I use a scoop of soda crystals in with the powder.