. Biofiltration is an important natural aspect in the aquarium. The amount of surface area for denitrifying bacteria to grow on will determine the health of a closed system. This past December, I decided to add a new 13.5 gallon nano reef tank, knowing it would not have a lot of space for live rock. Twenty years ago the recommendation was 1-1.5 lbs. of live rock per gallon. Live rock varies in porosity pending on the type and where it is sourced. An engineered biological media for denitrifying bacteria is a great alternative . I have used CerMedia’s MarinePure large blocks in all my larger systems for the last 10 years. I decided to try their “Gems” version for the new, small, all-in-one tank.

Product Description

The 90 gram box of product claims that it handles up to a 70 gallon tank. The individual pieces are ~ 20 mm with the entire box coming to “1450 inches square of surface area”.

Basic setup steps:

• Rinse bio-media in sink.
• Optional – place media in a mesh bag for easier handling
• Method 1: “Pre-colonize” the media with bacteria for a few weeks in an existing aquarium. Place the seeded media in a filtration chamber of the new tank
• Method 2: Place media directly in the media basket in one of the filter chambers after some mechanical filter to prevent detritus from clogging it
  • Use a bacterial supplement product to aid in the colonizing of the media and cycling the tank
• Maintenance: Clean detritus out by placing media in a separate container, agitate and rinse in existing tank water to avoid killing the existing bacterial

3 Month Update

I seeded the media in the sump of my existing system for a few weeks, adding it to the bottom chamber of a media basket. Dosed a bacterial supplement as instructed.

The system has been up for 3 months now. Yes, it still went through a short “ugly algae phase” but adding the proper cleanup crew at the early signs took care of it. The tank has a small bioload of LPS corals, “Clean Up Crew” invertebrates, and just 4 nano-fish: a Tailspot Blenny, a Hectors Goby, and 2 Skunk Clowns. The biofilter capacity was a huge benefit in such a small package. Today, less is more as witnessed in many of latest aquascaping trends. This was only achieved by the advancement in biofiltration media.  Unfortunately, I do not have a magic performance metric rating to offer. Nitrate and phosphate levels are maintained within acceptable ranges. I can only offer the result of healthy livestock and a tank not needing 13.5-20.25 lbs. of live rock in it.

Note: If anyone is wondering about the Asterina starfish in this new tank. The starfish are live food for a harlequin shrimp in the tank. Small Asterina starfish eat algae as a side benefit. The population will naturally self regulate pending their food availability.