I don't think tropica's ferts contain urea or ammonia. It's more likely to be nitrates and thus it's detected in my nitrates test.
I will test it with an ammonia test and get back to you.
We dont know exactly what Tropica's ferts use, but it cannot be KNO3 because it would result in a much higher K value than they have. It might be a different nitrate salt, but some of us find this unlikely, as it is a lot more expensive to use those alternative nitrate salts, ammonia/urea is much cheaper, and money rules the world 😉
Hi all,
It almost certainly isn't the nitrate (NO3-).
Have a look at <"
Need advice....">
cheers Darrel
Well, here's the result of my simple experiment using tap water and API water test kit.
Unless we are doubting the accuracy (or efficacy) of API's water test kit reagents, I think it shows that Tropica's specialized ferts contain NO3- ions. The colour difference between the ammonia tests might be due to the colour of the ferts (greenish), but the difference between the nitrate test is night and day (we don't even need to talk about whether the tests are accurate down to a ppm level).
Nitrate toxicity
Regarding the toxicity of nitrates to fish, your paper recommends no more than 10ppm for low flow systems which most of our aquariums would fall under. And I think using aquaculture related research to inform us about toxicity of water parameters for our ornamental fishes is inaccurate for several reasons, with the most obvious one being that these fishes are much larger than most fishes we keep in the aquarium. The larger the fish, the more tolerant it will be of bad water parameters. But it is understandable that most, if not all research on this topic are on aquaculture related species because they are of commercial interest.
I'm going to cite a couple of recent papers regarding the toxicity of nitrates:
Pereira, A., Carvalho, A. P., Cruz, C., & Saraiva, A. (2017). Histopathological changes and zootechnical performance in juvenile zebrafish (Danio rerio) under chronic exposure to nitrate. Aquaculture, 473, 197-205.
Exposed Zebrafish (a model organism that is of similar size to my CPDs) to 7, 100, 200 and 400 ppm of nitrates for 28 days. Growth parameters tend to decrease with increasing nitrate levels. Histological damages tended to increase with increasing nitrate levels, particularly above 100ppm (lowest testing level). No histological damage was found at 100ppm,
BUT we have to note though that the experiment ended at 28 days. To see if concentrations at or below 100ppm would induce damage in the long term, the experiment would need to go on for way longer (we keep our fishes for longer than a month).
Yang, X., Song, X., Peng, L., Hallerman, E., & Huang, Z. (2019). Effects of nitrate on aquaculture production, blood and histological markers and liver transcriptome of Oplegnathus punctatus. Aquaculture, 501, 387-396.
Exposed Oplegnathus punctatus to 21, 165 and 299 ppm of nitrates for 28 days. Findings showed chronic health impacts upon juvenile Oplegnathus punctatus at 165ppm and they recommend doing more trials at lower concentrations establish toxicity.
Gomez Isaza, D. F., Cramp, R. L., & Franklin, C. E. (2021). Exposure to nitrate increases susceptibility to hypoxia in fish. Physiological and Biochemical Zoology, 94(2), 124-142.
Showed that 50ppm nitrates resulted in differences in haemoglobin concentrations of Bidyanus bidyanus that increased their risk to hypoxia.
Davidson, J., Good, C., Welsh, C., & Summerfelt, S. T. (2014). Comparing the effects of high vs. low nitrate on the health, performance, and welfare of juvenile rainbow trout Oncorhynchus mykiss within water recirculating aquaculture systems. Aquacultural Engineering, 59, 30-40.
Rainbow trout were exposed to low (30ppm) and high (91ppm) concentrations of nitrate over 14 weeks. Mortality began to increase for the high nitrate treatment only 1-week after treatments were initiated. From week 3 onwards, the high concentration group showed a significant difference in side swimming behavior (which I also observed in my CPDs as they started swimming at a 45 degree angle).
Li, L., Tan, L., Yang, W., Xu, X., Shen, Y., & Li, J. (2021). Conjoint applications of meta-analysis and bioinformatic data toward understanding the effect of nitrate on fish. Science of The Total Environment, 794, 148645.
This paper used meta-analysis and bioinformatic data to determine if nitrates have any negative effects on fish in general. They found that nitrate affected adult fish by altering gene expression and histology. It is interesting to note that nitrates have an effect on the cellular level as proved by the change in gene expression. Although the paper did not state numbers, the findings from this paper and the others I've read convince me that even low nitrate levels do have a detrimental effect on our ornamental fishes down to the cellular level (which we can't see). This definitely opens them up to further bacterial, viral or parasitic infection.
Again, my nitrate levels were at 80ppm when I dosed the ferts and it could've been anywhere from 80-159ppm as the next level of change is 160ppm for the API kit which is extremely different from the 'normal' levels at 20-40ppm (even if we say that the kit isn't accurate, the difference in results show that nitrates were indeed elevated by the ferts). My CPDs were fine for months before this increase in nitrate concentration. Just today I found 2 more CPDs with extreme dropsy. Tested my water and it came back 0 ammonia, 0 nitrites and 20ppm nitrates. So the most suspicious culprit was the high nitrates that might have caused health issues that only surfaced recently. 
