Purifying Bacto-Agar: Suggestions?

[Michael Deyholos]

To save money, I'd like to use bacto-agar (e.g. DIFCO) in place of noble 
agar as part of 
a solid growth medium for screeing seedling-lethal mutations in Arabidopsis.

I've heard of washing bacto-agar in cold TE or water for a few days in a 
cold room.  Apparently, the agar turns pure white after a few washes.

Does anyone else have experience with this?  

Anyone know of a supplier of "PHYT-AGAR"

Thanks,
Mike