Could you try inserting a bubble trap in your perfusion line? That could
solve that problem. 
As for your media turning yellow, this is probably due to a change in pH
caused by the CO2. I suggest changing the gas composition as this change
in pH could be affecting your cells!

Kind regards,

Deanne.

Deanne Catmull
Research Assistant and Health and Safety Representative
Melbourne Dental School
The University of Melbourne
720 Swanston St Carlton
ph: 9341-1577
fax: 9341-1597
-----Original Message-----
From: Confocal Microscopy List [mailto:[log in to unmask]]
On Behalf Of Kerstin Honer zu Bentrup
Sent: Thursday, 18 December 2008 8:41 AM
To: [log in to unmask]
Subject: Air bubbles in Bioptechs FCSe

Hello everyone - I am using the Bioptechs FCS3 chamber for live cell
imaging up to 24 hrs. 
Two problems for which I hope some of you might have a solution: after a
few hours I am 
getting air bubbles that start accumulating right at the inflow of the
perfusion tube (I am 
perfusing with a low flow perfusion pump). And second: the cell culture
medium in the 
supply reservoir starts to turn yellow after some time (I am gassing
using a CO2 controller 
on really low flow). Any ideas would be much appreciated!
Thank you!
Kerstin