Starting a Marine Aquarium with Bacteria

Starting a Marine Aquarium with Bacteria


Francois Neo’s Guide to a Trouble-Free Nitrogen Cycle.

Welcome to Your Mini-Reef City

Thirty years of salt under my nails have taught me one truth: the real heroes of every thriving reef are invisible. Before the first clownfish flashes its fins or the first coral polyp opens, there’s a hidden workforce moving in—bacteria.

Insider tip from me, Francois Neo: whether you’re cycling a 200-gallon reef or a tiny freshwater tank for your kids, the nitrifying bacteria are the same species. Salinity doesn’t scare them. You can seed a brand-new marine setup with bio-media from a freshwater tank—just keep it damp so the microscopic crew stays alive.

The Nitrogen Cycle—Nature’s Waste-Management Dream Team

1️⃣ Ammonia to Nitrite

Fish waste, leftover food and every tiny scrap of organic matter release ammonia (NH₃/NH₄⁺)—lethal in even small doses.

Nitrosomonas bacteria, oxygen lovers that live on live rock, filter sponges and every porous surface, rush in to convert ammonia into nitrite (NO₂⁻).

2️⃣ Nitrite to Nitrate

Nitrite is still nasty. Enter Nitrospira and Nitrobacter—they transform nitrite into nitrate (NO₃⁻), far less toxic but the perfect buffet for nuisance algae if you ignore it.

3️⃣ Nitrate to Nitrogen Gas

Deep in the low-oxygen pockets of your reefscape or a mature sand bed, anaerobic bacteria quietly finish the job. They turn nitrate into harmless nitrogen gas (N₂), which simply escapes at the surface.

That’s the nitrogen cycle—your tank’s silent life-support system.


Freshwater or Saltwater: Same Bacterial Superheroes

Science (Hovanec & DeLong, 1996) backs up what veteran reefers like me have known for years: freshwater and saltwater nitrifying bacteria are identical.
So if your buddy has a mature freshwater system, borrow a piece of his filter sponge. That damp, bacteria-rich media is pure gold for jump-starting your reef.

My Favorite Ways to Seed a New Tank

Fishless Cycling—My Top Pick

Why risk fish when you can cycle like a pro?

  1. Dose Dr. Tim’s One & Only live bacteria.

  2. Add pure ammonia to about 2 ppm.

  3. Test daily for ammonia, nitrite and nitrate.

When ammonia and nitrite drop to near zero within 24 hours of a fresh ammonia dose, the tank is cycled—usually in 10–14 days.

                                       

Seeding with Pre-cycled Media or Live Rock

Nothing beats moving damp, established bio-media (even from freshwater!) or quality live rock into your new marine tank. The bacterial jump-start can shave weeks off your cycle.

Bottled Bacteria Boost

Not all bottled cultures are equal, but a trusted product like Dr. Tim’s ONE & ONLY  (for the American Reefers) Or ASF "for my fellow European reefers" can give you a reliable, fresh start. Always check the expiration date—dead bacteria don’t cycle tanks.

 

Francois Neo’s Golden Rules for Happy Bacteria

  • Give them oxygen & flow. Good pumps and a strong filter keep your aerobic workforce thriving.

  • Keep parameters stable. 75–80 °F (24–27 °C), pH 8.0–8.4, salinity ~1.025.

  •  No chlorine, ever. Use RO/DI water, or treat tap water with a quality dechlorinating conditioner—like ASF AquaCleanse or Drtim's aqua cleanse "if you are in the USA" —before it ever touches the tank.

  • Offer real estate. Porous live rock and high-quality bio-media = luxury apartments for bacteria.

 

Patience Is the Best Additive

You’ll see ammonia rise, then nitrite spike, then nitrate climb. Only when ammonia and nitrite stay at zero for 24 hours after a fresh ammonia dose is it time to add fish—slowly. Let the bacteria grow with your bioload.

My mantra: “If you think you’re going slow, slow down some more.” Your future reef will thank you.

Long-Term Stability

Even after cycling, bacteria never clock out. Routine water changes keep nitrate under control. For extra credit, run a refugium or maintain a deep sand bed to boost natural denitrification.

Classic Mistakes to Avoid

  • Rinsing filter media in tap water—use tank water to protect your colony.

  • Adding all your livestock in one go.

  • Ignoring pH or temperature swings—bacteria hate instability.

References & Further Reading

Francois Neo’s Takeaway:
The nitrogen cycle is the invisible engine of every successful reef. Understand it, respect it, and—yes—borrow that freshwater filter sponge if it’s handy. Build your bacterial army first, and your fish and corals will reward you with a stable, vibrant marine world.



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