I just received four TrIton NDOC test results for four samples from my system: aquarium water, 0.22 micron filtered aquarium water, 0.22 micron filtered Ulva pond water (my algae nitrate scrubber) and skimmate (table below).
The first thing to note is that my aquarium water total organic carbon and total nitrogen (1st and 2nd table entries) rank amongst the lowest in an R2R survey of aquaria (see plot below the table). Keep in mind that total nitrogen is the sum of organic nitrogen and nitrate nitrogen. For my system, once nitrate nitrogen is subtracted, there is little organic nitrogen floating around. I don’t know if that is good or bad, or a “so what” observation.
Comparing the results for the tank water against filtered tank water, my first response was “I just wasted money”, but @taricha points out that the bacteria in the unfiltered tank water consumed some of the organic carbon. For this post, that is the explanation I will stick with but note that contamination and testing variation need to be eliminated as causes before crying eureka, So, filtering the tank water did not reduce organic carbon and nitrogen by removing particulate matter as I had thought but stopped organic matter from being consumed.
Filtered Ulva pond water shows a higher concentration of organic carbon and a lower amount of total nitrogen than filtered aquarium water. This result was anticipated because the algae in the Ulva pond are actively consuming nitrate. The excess organic carbon in the pond could be from algae exudate or just because the pond is richer in organic carbon waste from a high concentration of heterotrophs of all sizes. If I increased the flow rate to the pond, the water results would no doubt look more like those of the aquarium water.
And finally, does a skimmer remove a significant amount of organic carbon and organic nitrogen? The table below shows the total amounts of organic carbon and nitrogen (after subtracting nitrate nitrogen) for the aquarium (380 L) and for the average daily skimmate volume (1.5 L). Skimmate contains a larger percent of the total system organic nitrogen than organic carbon. I wonder what GAC removes every day? I have two more NDOC test kits left if anyone has an idea about testing GAC performance.
The first thing to note is that my aquarium water total organic carbon and total nitrogen (1st and 2nd table entries) rank amongst the lowest in an R2R survey of aquaria (see plot below the table). Keep in mind that total nitrogen is the sum of organic nitrogen and nitrate nitrogen. For my system, once nitrate nitrogen is subtracted, there is little organic nitrogen floating around. I don’t know if that is good or bad, or a “so what” observation.
Comparing the results for the tank water against filtered tank water, my first response was “I just wasted money”, but @taricha points out that the bacteria in the unfiltered tank water consumed some of the organic carbon. For this post, that is the explanation I will stick with but note that contamination and testing variation need to be eliminated as causes before crying eureka, So, filtering the tank water did not reduce organic carbon and nitrogen by removing particulate matter as I had thought but stopped organic matter from being consumed.
Filtered Ulva pond water shows a higher concentration of organic carbon and a lower amount of total nitrogen than filtered aquarium water. This result was anticipated because the algae in the Ulva pond are actively consuming nitrate. The excess organic carbon in the pond could be from algae exudate or just because the pond is richer in organic carbon waste from a high concentration of heterotrophs of all sizes. If I increased the flow rate to the pond, the water results would no doubt look more like those of the aquarium water.
And finally, does a skimmer remove a significant amount of organic carbon and organic nitrogen? The table below shows the total amounts of organic carbon and nitrogen (after subtracting nitrate nitrogen) for the aquarium (380 L) and for the average daily skimmate volume (1.5 L). Skimmate contains a larger percent of the total system organic nitrogen than organic carbon. I wonder what GAC removes every day? I have two more NDOC test kits left if anyone has an idea about testing GAC performance.
