John, I tried to get one of these to beta test and was communicating with Joerg from ATI. This is what he said about
the threadwheel.
QUOTE..
Hello Mike,
as you imaging it depends on the polution of your tank. If your BM is provided with the airflowmeter, it will show when it's time for cleaning.
Some user clean the pump once a month, another every 3 month.
There are competitors, who try to give the threadwheel a bad reputation. I want to say, we have no problems with the thread wheel at all.
In case, that the threadwheel will be damaged, you can order the material in states and make a new wheel in no time for little money.
Cleaning is required, when the airflow will decrease. You will see it, when it happens. Sorry, I cannot give you a better answer, because it differs from tank to tank
I hope, this will help a little bit.
Joerg