Bro, thanks a lot for your information.
I stay in Orchard but i can easily grab a Uber or MRT to these locations, no worries on transportation.
But it would be great if i can go to a one-stop shop (Specialized aquarium shop or hardware shop) to get all my items.
But i believe the items above are quite specialized PVC fittings for sumps and marine tanks.
Sigh...so hard to find these items...