Tor-Henning Iversen, 30. August 2021
Prof. emeritus, https //: bio-consult.net
With the knowledge that DabVs could remove coatings of salts on glass surfaces, the professional management decided that this would be reasonably easy to test on aquariums. Different designs of DabVs have been tested and common to all is that our hypothesis focuses on the fact that it is the galvanic properties that will be able to keep the water quality in the aquarium reasonably even over time. In addition, the subject management has gained experience with a test system for a simple measurement of E.coli and coliform bacteria – Colilert -18 Ò Test Kit. Based on individual packages with substrate for the bacteria that are added to a water sample of 100 ml and heating to 35 o C, samples with the presence of a lot of bacteria will get a strongly fluorescent yellow color. A subjective assessment of the color based on a scale that follows the test package provides a basis for being able to determine whether there are fecal coliform bacteria and / or E. coli in the sample. Using a simple spectrophotometer, one can create a standard curve to obtain more exact values of the presence of pathogenic bacteria in the water sample. Colilert-18 is the same method in principle that Eurofins AS uses for determinations of bacteria.
The technical implementation has been based on 2-3 aquariums of varying sizes which were followed with start-up in March 2021 after a thorough washing of the aquarium. Daily observations were made and three criteria were determined and assessed on a scale of 1-10 (10 is best):
- the fish’s general condition
- visibility in the water and
- the aquarium glasses examined with a view to excretion of salts
There is reason to emphasize that the fish in the aquarium reacted noticeably to the renewed water already in the first days after the DabV was put on. From being inactive in their movements, the tail tails (goldfish) in particular showed a significantly increased activity and this activity has continued even after the actual test period when the DabV is still on. Pictures of the aquarium’s condition were taken a number of times during the test period. Throughout the period, a DabV unit was attached to the outside of the aquarium. Once a week, tests of E. coli and coliform bacteria were performed using Colliert-18. The color of the test solutions was subjectively assessed without a spectrophotometric quantification.
While the conditions in the largest aquarium were followed over a period of 11 weeks, the trend was the same in all three aquariums. In summary, the following results were obtained:
- detected approximately the same amounts of bacteria in the aquarium as a consequence of the fish having a normal digestion (excretion of feces),
- this did not affect either the general condition of the fish or
- visibility in the water
- no evidence of deposition of salts on the glass after 11 weeks
It should be emphasized that the aquarium was not cleaned during the 11-week period. Only 1 liter of fresh water was added approx. once a week depending on the evaporation. The picture below is representative of the conditions in the aquarium throughout the test period.
Figure 1 . A photo taken at the end of the 11 week period. A DabV unit (small water generator) was attached with tape to the rear glass wall in the lower rear edge.