Rubble is an underrated yet fantastic substrate option for pico reefs and reef jars. It offers a natural look, excellent surface area for beneficial bacteria, and plenty of nooks for tiny critters to thrive.
Unlike sand or bare-bottom setups, rubble adds texture and dimension while helping with biological filtration. Whether you’re aiming for a minimalist scape or a microhabitat teeming with life, rubble can bring versatility and function to your tiny reef.
Here’s everything I know about reef rubble and how it might be a good fit for you.
Benefits of Rubble in Pico Tanks
Rubble provides an ideal surface for beneficial bacteria to grow.
These bacteria handle the heavy lifting of biological filtration, breaking down waste, and keeping water parameters stable.
In tiny pico tanks, where your filtration options are limited or non-existent, this extra surface area is definitely welcomed. Think of rubble as your tank’s natural cleaning crew, small but mighty.
Rubble also works as a sturdy base for small rock structures.
In a pico tank, space is tight, so I usually stick to one main rock on top of rubble pieces. This setup keeps things stable while adding dimension to the aquascape.
Plus, the nooks and crannies in the rubble give critters like copepods and amphipods places to hide and thrive, bonus points for biodiversity!
Unlike sand beds that can trap detritus deep down, rubble makes cleaning a bit easier.
Waste tends to collect in visible spots around the pieces, so you can just blast it with a turkey baster and siphon it out during water changes. It’s simple and keeps your tank looking sharp without much hassle!
Challenges of Using Rubble
Rubble can be a double-edged sword. If it’s not arranged carefully, it tends to trap detritus, basically uneaten food and other gunk.
Over time, this buildup can lead to nutrient spikes that cause algae blooms or harm your tank’s balance. I’ve learned the hard way that regular maintenance is important.
During water changes, keep an eye on those rubble zones and give them a gentle blast with a turkey baster to clear out any debris.
Small rubble pieces don’t always stay put, especially in strong flow areas. In pico tanks, where we often use air pumps for circulation instead of powerheads, those big bubbles can shift rubble, knocking into corals or whatever livestock you have.
To avoid this mess, pick rubble sizes that won’t get tossed around easily by your setup’s flow dynamics.
Water changes can also be tricky with rubble. Pouring water too quickly or using the “Forceful Pouring Method” can send rubble flying around like tiny wrecking balls.
This might damage corals or stress out critters. Instead, try using gentler tools like a turkey baster or pipette to control the flow and keep everything steady during maintenance sessions.
Choosing the Right Rubble for Your Pico Reef
For a 2-gallon pico reef, stick with rubble pieces about 1–2 inches in diameter. Anything larger can overwhelm the tiny space and make it look cluttered.
But now that I think of it using a lot of large pieces, it might actually be a pretty cool idea to try.
You’ll need around 1–2 pounds of rubble, depending on how much coverage or height you want. I like to start with less and add more if needed. It’s easier to adjust that way.
Live vs. Dry Rubble
- Live rubble from your favorite brand is great for jumpstarting your reef’s ecosystem since it comes packed with beneficial bacteria and microfauna. Depending on where it’s sourced, be ready for potential hitchhikers; some are helpful, and others are not so much.
- Dry rubble gives you a clean slate, which is nice if you’re avoiding pests. But during cycling, it can look rough (think diatoms and algae blooms). Don’t worry. That ugly phase passes eventually!
- Used rubble from local sellers can be a mixed bag. It might bring biodiversity, but it also carries risks like detritus or pests. If you go this route, give it a thorough scrub first.
If you’re unable to find a pre-made ruble, you can buy a piece of cheap live rock and carefully break it with a hammer. However, it can be quite dangerous, and I generally don’t recommend it.
CaribSea Frag Zone Life Rock works well and comes with pieces of all sorts of shapes and sizes. The smallest bag they offer is 1.5lb, which is perfect for getting started.
But small bags from other brands are tricky to find, so maybe you can split one with another reefer!
Rubble Arrangement Tips
In a small setup, every inch counts, and rubble lets you build dynamic areas without taking up too much space.
Stack or scatter pieces to form tiny caves or crevices. These spaces are perfect hiding spots for critters like copepods and amphipods, who love the safety of these nooks. Plus, they become breeding zones, boosting your tank’s biodiversity.
Once rubble settles, it can help anchor larger liverock while keeping things secure during water changes or maintenance. But, while smooth rubble is less likely to scratch your glass, it can shift if bumped. Sharper pieces stay put better but require careful handling to avoid damaging your tank or your fingers!
Always inspect everything and handle it with care to keep everything (and everyone) safe.
