Mackerel said...
From what I've learned about keeping saltwater fish (reading / asking) it seems the bigger the pool the easier it is to keep balance. This bio-filtration system interests me?
Gotta be careful too with the legalities of keeping salt fish, I saw some brillant pinkies in a tank at an aquarium shop and wanted to know about buying them, but they said it was illegal and you needed some sort of display license that only fish shops could get. Seemed a bit suss really.
On the bullshark note, you just make me so confident in the up-coming crab dives in the swan shortly! Bloody hell I haven't had a few big blues for a few months now, aching to get out there.
Haha yeah I've just starting going night time free diving off Blackwall Reach. Still waiting for that 'encounter' to finally happen. Actually trying to catch bullies to tag them, not just for fun

The bio-filtration...the same kind of thing you would do on any normal marine or freshwater tank. Nothing special. But you're definitely right, bigger the tank the more stable the water quality.
As for legalities...no problem. My Dad's office handles most fauna collection licenses in WA