Alright, let’s get straight into it, using lava rock in a reef tank?
Some reefers love it for aquascaping or as a cheap alternative to live rock. Others (myself included) are more cautious. Let me break down why.
Why Lava Rock Might Be Risky
Lava rock is an appealing option at first glance, but it has:
High Iron Content: Unfortunately, lava rock has a high concentration of iron and other metals. In your reef tank, this can lead to problems like algae blooms and coral discoloration. Excessive iron encourages problem algae to grow faster than you can scrape it off.
Potential for Silicates: Some lava rocks may leach silicates into the water over time, which can fuel diatom outbreaks (you know, that brown dust-like stuff that coats everything).
Unknown Sources: The biggest issue? Lava rock comes from various places with no way to guarantee what’s in it unless you test it yourself. One batch might be fine, while another could leach harmful substances like copper or zinc, both toxic to invertebrates.
In smaller setups, like nano reefs or vase reefs, these risks multiply because there’s less water volume to dilute any toxins. If something starts leaching into the water, it doesn’t take long for levels to become dangerous.
When Is Lava Rock Safe?
If you’re running a fish-only saltwater tank (no corals or sensitive inverts), then lava rock might be okay. Fish are generally more tolerant of slight fluctuations or impurities in the water compared to corals and anemones.
But even then, I’d recommend rinsing and soaking the lava rock thoroughly before using it, preferably for weeks, in freshwater with regular testing for any signs of leaching metals or chemicals.
Alternatives to Lava Rock
If you’re after something porous and natural-looking but safer for reef tanks, here are some better options:
- Dry Rock: Products like CaribSea LifeRock or MarcoRocks Reef Saver are designed specifically for saltwater aquariums. They’re clean, safe for corals and fish, and mimic live rock without introducing unwanted hitchhikers.
- Ceramic Media: Brightwell Aquatics Xport Bio Bricks or MarinePure blocks offer tons of surface area for beneficial bacteria while being completely inert.
- Real Live Rock: Live rock from trusted suppliers and local reefers remains one of the best options if you’re looking for instant biodiversity.
All these alternatives avoid the unpredictability that comes with using lava rock straight out of nature or from your local landscaping store!
What Should You Do If You Already Have Lava Rock?
Maybe you’ve already added lava rock to your reef tank. Here’s how you can minimize potential risks:
- Use test kits for iron and other trace metals if possible.
- Keep an eye on phosphate levels too since some types of volcanic rock may leach phosphates over time.
2. Run Chemical Filtration:
- Add activated carbon or products like ChemiPure Elite in your filter system.
- A phosphate remover like GFO (granular ferric oxide) could also help if you notice algae issues popping up.
3. Monitor Your Tank’s Inhabitants Closely:
- Look out for signs of stress in corals, like bleaching or darkening, and address any issues immediately.
- Watch out for excessive algae growth on surfaces near the lava rock.
4. Consider Replacing It Over Time:
- Swap out pieces gradually with safer alternatives mentioned earlier so you don’t disrupt your biological filtration all at once.
My Take? Play It Safe! I wouldn’t risk putting lava rock in my reef tank, not when there are so many reliable alternatives available today! Sure, it’s tempting because it’s cheap and easy to find at garden centers or hardware stores… but is saving a few bucks worth jeopardizing your corals’ health?
For fish-only tanks? Maybe it’s fine if you’re careful about sourcing and testing, but still not ideal compared to purpose-made aquarium rocks.
At the end of the day, keeping a reef tank healthy means minimizing unknown variables as much as possible, and unfortunately, lava rock introduces too many “what ifs” into the equation.
