Can I reuse the filter cartridge?

No. Once you have run your home brew through one, discard it into the recycle bin.

The filter cartridges are designed to be used with one batch of home brew. They will filter up to 20 gallons (I have tested them that far – they might go further). Most home brew batches are 6 gallons.

Never use the same cartridge between home brews unless you are blending them as you filter them. The filter cartridge retains some of the home brew and the next use will push it out into your other batch.

I often blend wine batches of similar grape varietals, such as Pinot Noir with Merlot. I will make 3 kits, let them go through the fermentation and racking processes, then blend them together before I bottle them. My technique (which works very well) is to use a 5 micron filter while blending.