Making a Pebble Cave
Aquarium Resources

Making a Pebble Cave

This guide on how to make your own pebble cave is written by Nick Pavlovski.
A valued member of our forum.

Making a Pebble Cave

This project was inspired by the AquariumLife DIY PVC cave project (, which I came across after perusing the originating article for the Coconut Shell Cave that was trialled here in the Forum midyear (

I wanted a cave for my Betta, because of the strong water flow from my internal filter. I didn’t want to use PVC piping as I wanted something tall, to accommodate the long fins. A plastic plant pot is an excellent substitute.

Plastic plant pot, never used, from hardware store
Stanley knife
Old toothbrush
Silicone Sealant for Aquariums
Old bucket

Preparatory step:
Remove any price tags from the plant pot and then give it some good soakings in fresh tap water. I gave it two overnight soakings in a bucket, changing the water each time. That should remove any residual chemicals leftover from the manufacturing process.

Step 1:
Use the Stanley knife to cut the pot. I cut the hardened rim off, made a nice tall cave entrance and cut a little chimney in the roof on the opposite side to the cave entrance.

Step 2: Open the silicone and apply it to as much of the pot as you can. Smear it around using the toothbrush so that as much of the surfaces as you can are covered uniformly. Do the same to inside the pot, too.
Step 3: Hold the pot in the bucket with one hand (but don’t let it touch the bucket) and with the other hand, pour substrate over the pot, trying to get it to stick to the silicone. Once there is a good enough bed of substrate in the bucket, you can place the pot in the bucket, and pour the substrate over it. Then use your hands to press as much substrate onto the silicone so that as much of the pot is covered with glued-on substrate as possible.

Step 4: Leave for 24 hours so that the silicone hardens.

Step 5: Repeat steps 2-4 for the areas left uncovered.

Step 6: Leave alone in an airy place for the full duration of curing. Selley’s requires a maximum of seven days to fully cure, so seven days it is!

Step 7: Admire your work.

Step 8: Give it a few hours of being rinsed and washed. This is to make sure no remaining toxins are going to harm your fish. Then dry it.

Step 9: On tank-cleaning day, put the pebble cave in as the second-last step.

Step 10: Congratulate yourself on a job well done! Watch your friends explore their new home.
Final comment: Use a really rigid plastic pot, unless you are using very fine substrate. My substrate weighed down the pot a fair bit and caused the walls to buckle a little.


Copyright Nick Pavlovski 2007.


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