The 25 metre pool is attached to the kids' section. It is often unavailable to the public because of swimming lessons (the 50m pool is usually fine, but you can check on their web site). Lessons are run quarterly, and fill up quickly. The swim instructors are excellent.
Toddlers and younger kids adore the kids' play area - it gets gradually deeper, so they can find their own comfort level, and has loads of fun fountains, waterfalls, and an island for jumping in as their confidence grows.