Our Biome Cycle Experiments continue as Ryan serves up the phase #1 AquaBiomics test results from test tanks #5 through #8. Relative to test tanks #1 through #4, these results are equally interesting in that there are clear winners in terms of producing a diverse and balanced biome right out of the gate. 


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As a quick recap, phase #1 of the experiment lasted a total of 15 weeks. The idea was to examine how the biome develops over the first few months before the introduction of pests that typically come with the addition of corals, fish, and other livestock. Keep in mind that we are not focusing on only the nitrogen cycle rather we are looking at ALL of the various bacteria that develop, nitrifying or otherwise. Each tank was set up using a slightly different approach in terms of substrate and introduction of a biome so we can see exactly how the various approaches affect the development of a diverse and balanced biome. 

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

For congruency's sake, we collected samples for AquaBiomics testing at the same time from every tank throughout the experiment. The results are documented below along with some interesting observations that could only be made using the AquaBiomics DNA testing reports. 

Test Tank #5 - Insta-Coral: Dry Rock, Dry Sand, and Coral

Test Tank #5 - Week 2 AquaBiomics eDNA Test ResultsWeek 2
Test Tank #5 - Week 10 AquaBiomics eDNA Test ResultsWeek 10
Test Tank #5 - Week 15 AquaBiomics eDNA Test ResultsWeek 15

This is an approach that is quite common for more experienced reef tank owners where a tank is stocked with living coral on day one. The idea is that coral brings living biome on its flesh and substrate to seed the tank with diversity. There is nothing stopping the uglies like algae and pests from hitchhiking on coral so the bad comes right along with the good.

As expected, green hair algae showed up within the first couple of weeks and continued growing up until week 8 when it started to die. By week 10, the algae had disappeared.

Why did the algae disappear? We can only hypothesize be presumably the balanced biodiversity played a role in out-competing the algae for what minimal resources were in the tank. Microcrustaceans (copepods) along with other scavengers like "red flatworms" were evident in the tank too which could have had some effect on the growing microalgae. We also should note that clean-up crew animals and herbivorous fish were NOT added to the aquarium which would have likely changed the trajectory.

As the test continued, algae never reared its head again but a distinct purple slime started to show up just before reaching week 15. We guessed it was a type of cyanobacteria but the verdict is still out.

Test Tank #6 - Dark Cured Rubble: Dry Rock, Dry Sand, and Cured Rubble

Rather than pull the shared biome from the sand bed of an established aquarium like we did before, we used a piece of established rubble rock (from Ryan's 360) that was cured in an area without light instead. The shared rubble was placed into the rear filtration chambers with no significant source of light. Will this dark-cured rubble placed in a low-light area result in less transfer of photosynthetic pests? 

Test Tank #6 - Week 2 AquaBiomics eDNA Test ResultsWeek 2
Test Tank #6 - Week 10 AquaBiomics eDNA Test ResultsWeek 10
Test Tank #6 - Week 15 AquaBiomics eDNA Test ResultsWeek 15

Interestingly enough, the tank was very clean through the first few weeks and we noticed signs of copepods almost right away. By week 6 diatoms bloomed, the following week those diatoms were replaced by light green algae, and by week 10 cyanobacteria started to grow. Notice a balance score in the 79% range which is among the highest throughout our entire experiment. This supports the idea that no single organism is winning the battle for resources when this kind of balanced diversity is achieved. 

At week 10, we cranked up the lights to hit PAR levels appropriate for SPS corals which did create a boom in cyanobacteria but again, the problem resolved itself by week 12. After the cyanobacteria died, we started to see the formation of chrysophytes and hair algae as the tank reached the 15-week endpoint.

This tank retained a high balance score throughout all of the small pest outbreaks and also sustained a population of microcrustaceans. All in all, it was one of the best performing tanks in all of our tests and throughout phase #2, it continues to be one of the most resistant tanks in terms of photosynthetic pests.  It seems that using established donor media does work with minimal transfer of pests, but only when pulled from an area that does not get light and is placed into a similar environment in the new tank. 

Test Tank #7 - Established Rock & Sand

For this shared biome approach, 100% of the rock and sand were pulled from Ryan's well-established 360-gallon aquarium. In this case, both the rock and sand had been exposed to light in the 360 and then placed into the display of the test aquarium where it will again be exposed to light throughout the test.  Will photosynthetic pests be problematic like we saw in test tank #4?

Test Tank #7 - Week 2 AquaBiomics eDNA Test ResultsWeek 2
Test Tank #7 - Week 10 AquaBiomics eDNA Test ResultsWeek 10
Test Tank #7 - Week 15 AquaBiomics eDNA Test ResultsWeek 15

For the first four weeks, the rock was essentially going through a dark cure so it actually started to clean up during this time. We immediately saw signs of microorganisms including pods, worms, and even a sea fan that were transferred from the previous tank.

As soon as we turned on the lights, diatoms showed up around week 6, which went away within 7 days. After the diatom bloom algae started to grow which turned into a hair algae factory leading in week 9 when we cleaned the tank before going into the final stage with much higher levels of light.  Sharing a biome like this certainly introduces photosynthetic pests and the proliferation of those pests is likely made possible by the extra nutrients and organic waste that come with used sand. 

Throughout the final 4 weeks, the hair algae stay but never really gets much worse. During the cleaning, we buried a considerable amount of hair algae which probably helped curb its growth through the end stage of the experiment. The coralline algae appeared to start bleaching during this time and the balance score dropped by almost 20%.

While this method wasn't the worst performing test, it is difficult to replicate for most hobbyists and we had much better results using a piece of rubbled that had been dark cured and placed into the sump.  

Test Tank #8 - Dry Rock, Dry Sand, and 100% Water from BRS160

This is an interesting test because instead of transferring biome that grows on surfaces (rock & sand) we are using established water from the BRS160.  Are there enough beneficial organisms suspended in the water to transfer a diverse biome?  

Test Tank #8 - Week 2 AquaBiomics eDNA Test ResultsWeek 2
Test Tank #8 - Week 10 AquaBiomics eDNA Test ResultsWeek 10
Test Tank #8 - Week 15 AquaBiomics eDNA Test ResultsWeek 15

The first four weeks were uneventful with nothing really showing up until the diatom bloom during week 5.  Right after the diatoms cleared, photosynthetic pests begin to show up but are not incredibly severe. While we suspected the pests to take off after cranking up the lights, instead the pests did the exact opposite. Both algae and chrysophytes start to weaken and die off through the final four weeks of the test.

It's obvious that some photosynthetic pests were transferred with the water along with some amount of biome based on the diversity and balance scores but certainly not the best. The tank ultimately ended up looking decent without any terrible pests but phase #2 of our experiment will tell a different story where this tank's resistance to introduced pests is all but non-existant.