The Aquabiomics results from our microbiome cycle experiments are in! Ryan shares the phase #1 Aquabiomics test results from the first four aquariums in our Biome Cycle Experiment. We find out just how much your particular approach to cycling a new saltwater aquarium matters in terms of producing a well-balanced microbiome. We also make some intriguing insights into why each of the various aquariums developed so differently throughout the experiment.

If you landed here and have not yet watched the first few episodes of the Biome Cycle Series, circle back to find out exactly how we set up the experiment and how we are measuring the health and success of each aquarium. 

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As a quick recap, phase #1 of the experiment lasted a total of 15 weeks and we collected samples for AquaBiomics testing and the same time from each tank. Phase #1 is the initial cycle and helps us understand how the microbiome develops before the introduction of pests that typically come with the addition of corals, fish, and other livestock. Phase #2 will be shared later in the series and explores how each of these various tanks holds up to the intentional introduction of pests. 

Phase #1

  • Week 1 - 4: Dark zone, no lights
  • Week 5 - 10: Moderate lighting appropriate for LPS corals
  • Week 11 - 15: High output lighting appropriate for SPS corals

Test Tank #1 - Wet Indonesian Live Rock & Dry Sand

Classically, live rock has been considered to be one of the BEST options for establishing a new aquarium because of the biological diversity the rock carries into the tank. What we find out is that diversity is not always a good thing, especially when the bad is introduced alongside the good. Based on our observations and the thousands of tanks tested by AquaBiomics, it is more important to have a well-balanced microbiome with the right kind of bacteria and microorganisms dominating the aquascape as opposed to just sheer diversity. 

Test Tank #1 - Week 2 AquaBiomics eDNA Test ResultsWeek 2
Test Tank #1 - Week 10 AquaBiomics eDNA Test ResultsWeek 10
Test Tank #1 - Week 15 AquaBiomics eDNA Test ResultsWeek 15

Right out of the gate, the live rock aquarium tested well on the diversity scale (26%) but the balance score of only 18% shows us that the diversity was not well-balanced, at least not in the way observed in healthy aquariums. After 10 weeks, the diversity score dropped considerably but the balance score skyrocketed up to the 82nd percentile. This suggests the right bacteria families were winning the microbiome battle for resources. Through the final testing stage, the microbiome balance score shifted presumably because photosynthetic pests (chrysophytes) started to gain traction.

In terms of visual performance, the tank saw the growth of microcrustaceans almost right away and continued throughout the entire test. A quick diatom bloom came and went around week #7 and opportunistic algae showed up as soon as we turned on the lights. When we cranked up the lights past week #10 golden algae (Chrysophytes) started to grow and quickly took over the entire aquascape which remained through the end of week #15. 

Are there better ways of preserving the diversity of live rock while also eliminating the risk of photosynthetic pests?

We hope to explore this question in future episodes and find out if dark curing live rock is a viable way of getting rid of photosynthetic pests while preserving the benefits of a diverse biome. 

Test Tank #2 - Dry Rock & Dry Sand

This method is often called the "sterile approach" because the dry rock and sand do not contain any kind of living biome which means no risk of pests but also no beneficial bacteria. Throughout the experiment, we referred to this tank as the "control" because we expected it to perform the worst in terms of microbiome diversity and struggle with photosynthetic pests. Interestingly enough, the AquaBiomics eDNA testing revealed something completely different and the control tank was one of the best performers throughout the phase #1 experiment.

Test Tank #2 - Week 2 AquaBiomics eDNA Test ResultsWeek 2
Test Tank #2 - Week 10 AquaBiomics eDNA Test ResultsWeek 10
Test Tank #2 - Week 15 AquaBiomics eDNA Test ResultsWeek 15

After the first two weeks, the AquaBiomics tests came back as expected with extremely low diversity and balance scores.  After turning on the lights for 6 weeks, the balance improved considerably to 66% meaning the tank was more balanced than over half of the healthy tanks AquaBiomics has tested! After the final phase of high output lighting, we were surprised to see the diversity score jump way up to 24% and the balance improved even more to 90%. This is the best balance score throughout all of the tanks. It seems the microbiome had a chance to develop without competition from photosynthetic pests and the lack of diversity helped to produce these desirable results.

The sterile tank remained almost unchanged through the entire 15 weeks aside from a minor diatom bloom that resolved itself inside of 7 days. Small amounts of algae showed up around week#10 but never took off and the tank looked just as clean at the end of the test as it did on day 1. 

Does the "sterile tank" approach inhibit the ability to develop a diverse biome?

It appears you can develop a stable and healthy biome using dry rock and sand without gathering biome from other sources. Photosynthetic pests were never an issue throughout the cycling process either and we are curious to see how the tank holds up to the introduction of pests. This also begs the question, where did the diversity come from? Could it be the food or the fish's digestive tract?  Answers we don't yet have but certainly interesting considering the tank was sterile to start but ended up just as diverse and balanced as any of the others. 

Test Tank #3 - Dry Rock & Caribsea Ocean Direct Live Sand

Ocean direct sand is pulled out of the ocean and is never sifted or sorted so as to preserve the live bacteria covering the small grains. The proposed benefit to your tank is the addition of bacterial diversity without the expense and risk of photosynthetic pests you get with live rock. 

Test Tank #3 - Week 2 AquaBiomics eDNA Test ResultsWeek 1
Test Tank #3 - Week 10 AquaBiomics eDNA Test ResultsWeek 10
Test Tank #3 - Week 15 AquaBiomics eDNA Test ResultsWeek 15

The AquaBiomics eDNA testing certainly supported or proved that Ocean Direct sand does introduce a level of biological diversity and we never observed any kind of severe photosynthetic pests throughout the entire test. Aside from 7 days with a diatom bloom, the tank went virtually unchanged for 15 weeks. While the scores were not initially impressive, over time the beneficial bacteria families started to balance out and ended up scoring the 4th highest in all of the test tanks on the eDNA Balance Scorechart. 

Does Ocean Direct Sand really benefit the biome?

Similar to the sterile tank, Ocean Direct is looking like a great option for building a well-balanced biome and does not appear to contain or cause photosynthetic pests. It will be very interesting to see how these tanks hold up against the introduction of various pests through the next phase of our experiment. 

Test Tank #4 - Dry Rock, Dry Sand & 2 Cups of Aquarium Live Sand

We added 2 cups of sand from a well-established aquarium (Steve's Tank) into an otherwise sterile aquarium filled with dry sand and rock. This "shared biome" method is thought to have a positive benefit on the microbiome by borrowing diversity from another tank. The diverse biome of the established tank gets transferred into the new tank but you really have no control over what exactly gets shared between the tanks and how those shared microorganisms develop in the new tank (new environment). Just like we saw in the live rock test tank, diversity isn't always a good thing for a new aquarium.  

Test Tank #4 - Week 2 AquaBiomics eDNA Test ResultsWeek 1
Test Tank #4 - Week 10 AquaBiomics eDNA Test ResultsWeek 10
Test Tank #4 - Week 15 AquaBiomics eDNA Test ResultsWeek 15

After the first two weeks, both scores came back fairly low but it was interesting to see the makeup of the biome was almost identical to that of the Ocean Direct tank.  When we turn on the lights the tank takes a turn for the worst and immediately experiences a heavy diatom bloom. In the following weeks, Algae begins to grow directly on the patch of sand that came from the donor tank which suggested that the sand contained photosynthetic pests, even though the algae wasn't visually growing at the time of sharing it. The algae were not growing on the rocks or anywhere else on the sand bed, only in a small patch that contained the shared sand. 

After week #10, the algae stopped growing and what appeared to be chrysophytes showed up on the rocks. The chrysophytes never exploded as we saw in the live rock tank but something else showed up toward the very end of the test. An orange slime appeared that we identified to be some kind of persistent diatoms, one of the peskiest of pests. 

Should I use donor sand for my new aquarium?

Based on the observations here and the AquaBiomics test results, sharing sand from another tank seems to only bring the bad and you can achieve the same biome balance and diversity without the photosynthetic pests by using OceanDirect sand instead. Alternatively, you could cure the donor sand without light for 4 months (to presumably get rid of pests) but again, the Ocean Direct is just an easier option.