Leopard seals have been in the collection as far back as 20 years. I have an old guide book from 1988 with a leopard seal at Taronga. So the overhaul took 20 years?
You say that a facility can't just use what they have they have to upgrade but, then you say you didn't need to upgrade the old pools for leopard seals. What is different in the new pool to the old pool?
I realise this, the thing we have to take into account is that zoo have changed over that time. Also if you remember brooke moved down to seal bay when those pools opened in the early 90's.
The new pool number 1 has a filter and a chiller, more interesting enclosure layout for her, deeper pool, the underwater viewing window adds enrichment for her as well.