The signal that you are sampling has a very slow frequency, so reaching a sampling frequency of .6Hz (the minimum sampling frequency without aliasing should not be an issue). The FP-AI-100 has a max update rate 357Hz. However, if you feel that you may be picking up stray frequencies from noise, such as 60Hz noise from a power line, you may want to use an anti-aliasing filter. You could use a low-pass filter with a cutoff of lets say 4Hz. This would remove any kind of interference that you may be sampling on that channel.
Please see this KnowledgeBase for more information:
KnowledgBase 207D87LJ - Why Should I use Anti-Aliasing Filters