Did you cut the red wire on the usb cable that connects the pi with the first hub to prevent backpower?
My pi with 5 erupters runs fine for about a week on average before crashing. Maybe someone can help on how to find what's causing the crashing...
No I did not. The hub connected to the Pi is unpowered, should I still cut the red cable?
Would it be better to chain my powered hubs and then plugging them directly into the Pi?
The unpowered hub is leeching power from your Pi's. That's why they are crashing. Try connecting a good Powered USB Hub without backfeed between the Pi and other peripherals. You should never use an unpowered hub directly with a Pi since it will always leech power.
You can check the reports on various powered Hubs with the Pi here:
http://elinux.org/RPi_Powered_USB_Hubs