I was always considered bacteria plankton, one of the best food sources for more of our corals, if o2 levels are not affected. And one major reason i am no using skimmer either. Can you give us a link to those studies showing the opposite?
This was a comment I read from Steve Tyree.
“There are direct correlations with poor coral health and high pelagic (water column) bacterial densities. Some dissolved organics will always be present within a closed system. The issue is density. That is why skimmers were needed to become successful with Acropora initially. “
Tyree's comment reminded me of an observation Feldman made in his paper -
http://www.advancedaquarist.com/2011/3/aafeature
Bacterial Counts in Reef Aquarium Water: Baseline Values and Modulation by Carbon Dosing, Protein Skimming, and Granular Activated Carbon Filtration
By Ken S. Feldman
3. Results and Discussion
The surveyed reef aquariums divided into two distinct sets of husbandry protocols;
aggressive and
passive. The aggressive husbandry practices included protein skimming, GAC filtration, and regular water changes in an active effort to scrub the water of nutrients. The passive approach did not involve any of these procedures. Interestingly, the aquaria subjected to
passive husbandry exhibited bacterial counts that fell
within the range seen on authentic reefs; 200 - 1000K/mL. On the other hand, the tanks that "benefited" from careful attention to nutrient removal protocols displayed bacteria/mL counts that fell
far short of these numbers. In addition to monitoring water column bacteria counts, the TOC levels were examined as well. Not surprisingly, the tanks with "unpurified" water exhibited TOC levels greater than those seen with the skimmed/GAC-filtered tanks. The "purified" aquaria's TOC levels fall within the typical TOC range seen on authentic, healthy reefs; the passively husbandry tanks were 2-3x higher.
The observation that, at least among this small set of aquaria examined, the water within the skimmed/filtered tanks had only ~
1/10th of the population of (water column) bacteria that the unskimmed/unfiltered tanks had was a real surprise. It speaks to one aspect of aquarium husbandry in which a perhaps important parameter (?), water column bacteria counts from authentic and healthy reefs, is not reproduced at all effectively in these home aquaria.
Sensitive corals, like Acropora, do not thrive in the high-bacteria-count/high-TOC-level tanks examined, although soft corals do well. On the other hand,
SPS corals do well in the low-bacteria-count/low-TOC-level tanks.
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Although Tyree may have be referring more so to an increase in the percentage of heterotrophic & virulent bacteria specie densities, created by higher percentage of certain sugars contained in DOC from various primary producers on unhealthy reefs, Feldman’s observation would suggest that certain densities of water column bacteria, above a certain concentration, are detrimental to sps corals no matter the bacteria type.