Kick starting new tank with pre conditioned water.

Hello,

I have just purchased a 300 litre aquarium to be used for Tropical 
freshwater.

I already have an established 100 litre aquarium, and I do partial water 
changes every 4 or 5 days.  Can I kick start this aquarium with 50 litres
of 
the other tanks water?  Or should I start afresh?

Regards,

Gary.