The Nano-Tech Anaerobic Block is a biological filtration media from Maxspect’s Nano-Tech Bio-Media line. Its primary role is denitrification — that is, reducing nitrate levels in aquarium water by cultivating anaerobic (oxygen-free) bacteria that convert nitrates into harmless nitrogen gas. This helps “export” excess nutrients (nitrate) from the aquarium and completes more fully the nitrogen cycle. It is intended for both freshwater and marine aquariums.

How It Works

• The blocks are made from nano-ceramic beads treated with a proprietary method to favor growth of anaerobic heterotrophic bacteria (e.g. Paracoccus denitrificans, various Pseudomonas species). These bacteria thrive in low- or no-oxygen (anoxic) environments, and are capable of reducing nitrate to nitrogen gas.

• To create that low-oxygen condition, Maxspect recommends using two blocks stacked horizontally, with a Denitrification Catalyst placed between them. This catalyst enhances or accelerates bacterial activity, but it is consumed over time and requires periodic replacement (often ~ every 2 months).

• The porous structure and very high internal surface area of the blocks give bacteria many microscopic crevices to colonize. This maximizes the “real estate” for bacteria, which improves denitrification efficiency. The ceramic does not degrade in this process.

Specifications 

• Each block measures about 97 × 97 × 25 mm (that is ~3¾″ × 3¾″ × 1″).

• Surface area per block is extremely large: around 1,025 m² (~11,033 ft²) of internal filtration surface.

• The product is sold (typically) as pairs: two blocks are recommended. Two blocks are capable of treating up to about 1,000 liters (≈ 264 gallons) of aquarium water.

Installation of Maxspect Nano Tech Anaerobic Block

To get the best performance from the Anaerobic Blocks:

1. Placement: These blocks are usually placed in the sump or technical tank. They should be stacked horizontally. The Denitrification Catalyst is positioned between the two blocks. This configuration helps create an anoxic (low-oxygen) “sandwich” where anaerobic bacteria can thrive.

2. Flow conditions: Ensure that water flow is sufficient but not so strong that oxygen is forced into the inter-block space. The aim is to maintain a low-oxygen environment. Turbulence should be minimized around the catalyst region so that anaerobic activity is preserved. (While Maxspect doesn’t always give exact flow rates, user-reports and reviews emphasize gentle flow in the block region.)

3. Catalyst replacement: The Denitrification Catalyst component needs replacement every ~2 months to maintain effectiveness, since it’s gradually used up as the bacteria act upon it.

4. Cleaning / Replacement of the Blocks: For optimal long-term performance, the blocks should be cleaned or replaced every 6 months. But critically: do not replace or clean all blocks at once. Replace/clean only about half at a time so that existing bacterial colonies remain and can re-colonize the freshly cleaned/replaced block(s). This prevents sudden drops in denitrification activity.

Advantages of Maxspect Nano Tech Anaerobic Block

• Very high surface area per block means efficient colonization and hence strong denitrification potential.

• Compact size makes it easier to integrate into sump systems without needing large reactors.

• Works for both freshwater and saltwater setups.

• Proprietary treatment of the ceramic ensures that the media supports anaerobic bacteria well, not just aerobic bio-filtration.

• Helps complete the nitrogen cycle (i.e., moving from ammonia → nitrite → nitrate → nitrogen gas) which many filtration columns or media don’t fully address.

• Reduces nitrate buildup, which in turn helps avoid algae overgrowth, improves coral health, reduces frequent water changes.

 What to Watch Out For

• Requires proper setup: must be installed with correct spacing & flow, and with the catalyst, to maintain anaerobic regions. If oxygen leaks in (too strong flow, excessive mixing), anaerobic bacteria may be suppressed.

• Catalyst replacement every ~2 months adds recurring cost. Forgetting to replace may degrade performance.

• Cleaning must be done carefully (half at a time) to avoid loss of bacterial colonies. Improper or simultaneous replacement of all blocks can lead to nitrate spikes.

• The blocks themselves are somewhat fragile materials (ceramic), especially during transport; they can crack or break. Some retailers warn that cracking during shipping may occur, and while it may not affect performance, it’s something to be aware of.

• For aquariums with extremely high bioload or very high nitrate build-up, multiple or more powerful denitrification systems may be needed in addition. The blocks have capacity limits.

Practical Tips 

• Monitor nitrate levels regularly, especially in the first few weeks after installing the blocks, to assess how quickly they are reducing nitrates.

• Keep an eye on flow patterns in the sump: ensure that stagnant zones are avoided except in the intended anoxic region.

• When replacing catalyst, keep track (e.g. calendar reminders) of approximate 2-month intervals.

• During block cleaning, rinse gently in aquarium water (not tap water with chlorine etc.) to avoid killing off beneficial bacteria.

• Consider placing the blocks where they are easily accessible for maintenance but where light and oxygen intrusion are minimized (light / oxygen often interfere with anaerobic zones).

Observations 

• Reviews and hobby articles suggest the blocks do work as advertised: that nitrate reduction is observable over time when installed properly.

• Because the technology is relatively new, long-term performance over many cycles (cleanings, catalyst replacements, etc.) is still being assessed, though early user feedback is positive.