I use a device made by Hanna Industries called a pHep - HI 98107.

This is a simple, pocket sized meter that reads to one decimal place. It's
available form local scientific supply places fairly readily - about AU$100
IIRC. Their web site is www.hannainst.com

Its more reliable than an egg - that really only works for salt levels, not
pH - and I find a home brew shop will sell me a beer brewing hydrometer for
about $20 that does the job easily enough for determining the amount of salt
in the brine - but you do need a conversion chart to take you from Specific
Gravity to salt percentage.

Regards,

Mike Wilson
Hunter Valley.