Algae

Algae is definitely starting from the edge of the APS units where the capillary mat meets the water source. 

The picture to the left shows the capillary mat of the APS-6 unit that was holding the Winter Melon seedlings.  This is only have 2 weeks of use.

This defintely cuts down the usefulness of the APS units.  They are very convenient to use.  I only have to water once every few days.  The APS-24 units are great for germinating seeds.  But Algae just grows too quickly.  I don't know if this is artifact of how the APS unit is put together or if all self-watering containers have the same problem.