I would not take a child under the age of 5 because I don't think they would truly 'appreciate' the experience. We are from Southern California and know first hand what larger aquariums offer, and we are still glad that we went.
We couldn't purchase those discounted tickets online, but had no problem getting in because of when we went. We are 'seniors' so we got in for $10 each, a fair price for our adventure - but we would have paid the $13 regular price as well. The staff is very knowledgeable and passionate about the sea life. But for maybe 5 other guests, we had the place to ourselves which was great. We spent 2 hours leisurely walking through the aquarium. My husband and I went mid January on a Thursday at noon, which was a perfect adventure for a rainy day. Sharks, seahorses, moray eels, rays, and beautiful tropical fish. I would tell anyone, with a couple of hours to spare, to visit this aquarium if they like aquariums in general.