454 Maintenace wash

[bia]

Hi everybody!
I'm using a 454 system, the Roche manuals recommend to perform a maintenance wash every 7 days if you are not using the instrument.
Do you follow this rule?
Does anybody perform the maintenance wash every 3-4 weeks? have you ever had problems due to growth of microorganisms in the system?
The maintenance wash should be 0,5% bleach, does anybody prepare the wash by itself instead of buying it?

Thanks a lot,
Francesca

[Carrie]

We don't usually do them every 7 days, but if it is not run for more than 10 then we will. We have not noticed any growth, but our machine is relatively new, less than a year old and for the first few months we didn't do many runs.

We have also contemplated making up our own bleach solution. When we got our titanium upgrade training I asked our very friendly Roche trainer about this, and she did not recommend it because apparently someone had been doing this, but ended up using too concentrated bleach and had to replace the whole sipper manifold at quite a cost.