What do the white membranes do?

[Snow mom]

What do the white membranes on the PISA do? How does changing them help output? Every now and again I see reference to changing them and I think "gosh, I really should do that" but I still haven't :bag. I always keep my pump on the lowest suction, and I imagine they are related to creating suction so I'm not sure if changing them would really help anything (not that I have a problem other than DD is a little piggy who will drink 20 oz. in 6 hours of daycare.)

[Momof3Labs]

They close when the pump is sucking milk out, creating the suction. Then they open and the milk falls into the bottle. When they are old/worn out, they don't close fully, so you aren't getting as much suction, and thus reducing your output.

To really maximize your output, you need to get off of the lowest suction setting all the time. Start pumping at a fast speed and the lowest suction, but as soon as you start to get a letdown, switch to slow speed and the highest suction that is comfortable for you. When the letdown ends, switch back until another letdown and so on. This best mimics your baby's suction pattern, which will definitely maximize your pumping output.

And get those membranes changed - it will make a difference.

Keep in mind, too, that this is all tied into maintaining your supply. If you haven't been pumping effectively, your supply will drop over time.

[Snow mom]

Okay, that's what I thought they do. I actually find I have to keep the pump set pretty low and just pump for longer if I'm going to pump both sides at the same time. My lower producing side doesn't handle the pump suction being much higher. I'm still figuring out what works best for pumping that much milk. I've been pumping since DD was born, but only for the milk bank and an occasional bottle for DD. Keeping DD fed at daycare is a whole other beast.