JM -
You can run more than one diffuser on that pump. Just hook that PVC into an underground vavle box and you can run upto 4 air lines. (Depending on what type of diffuser you want to use) To get the most out of your pump, you should consider housing with plenty of ventilation to keep the ambient temperature down.
I talked to Ted earlier today - he is in the field most of the day, but I'm sure he will get in touch with you this evening.
