Coronal Mass Ejection Carl

Other weirdness in the Rubin study: Their ammonia LC50s are quite high. It's total ammonia but the pH isn't that low. I wouldn't expect ammonia and nitrate LC50s to be that close.

Needs to be adjusted upwards for life stages older than fry and also because the Rubin 1977 study used potassium nitrate which is more toxic than sodium nitrate. Later papers put an asterisk by the KNO3 studies because they now know KNO3 is more toxic.

This is probably the guppy study she was referencing: Pretty high numbers that would probably be even higher for older life stages.

3 out of 8 in the 1,000 mg/L nitrate-N group in the Monsees study died. That's 37.5% in ~30 days. 96-hour LC50 where half die after 4 days is probably going to be higher. One way to determine what chronic exposure level would be tolerable is to take 10% of that value.

Why doesn't everyone do two 90% water changes per day like some discus keepers? You don't do two 90% water changes per day? You're defending pollution. Did you not put on sunscreen to get the mail? You're defending skin cancer.

The good news is that you basically don't have to test nitrate. And you don't have to worry about 20 vs. 40 or even 80 ppm. They are all equally non-toxic. You know who Diana Walstad is? Well... And this was before even better studies came out.

I accept your concession.

Ah, yes, the old Isaza article. That paper states that: Which is interesting because the Monsees paper doesn't say that at all. Monsees is a pivotal paper in nitrate toxicity research because it finally answers the question of how nitrate gets into fish: In the early days, scientists thought it could be through the gills since a lot of ions pass or are transported through them. But later studies found that gills were fairly impermeable to nitrate which left them wondering what alternative routes could there be. Isaza also cites Camargo which is just a review paper that I don't believe performed any experiments. It mentions branchial permeability twice: Both of those studies are pre-Monsees so it likely never occurred to them to consider incidental ingestion. Regardless, they failed to control for it so they can't legitimately conclude that any nitrate uptake, however minor, was via the gills. So, basically, Isaza cites Monsees as support for branchial uptake when in fact Monsees concludes it's not branchial uptake. Then it indirectly references two old studies that didn't consider and prevent incidental ingestion. And in its own experiments, Isaza makes the same mistake. This is on top of the fact that the alleged branchial uptake only occurred when the fish were exposed to extreme pH levels.

Anybody can do that. It doesn't make you an authority on the subject. Have you kept track of the lifespans of the fish you sold? Do they live longer than breeders who change water less frequently? Really? Which fish? Scientific evidence required. I have provided scientific evidence. All you have is an opinion. You still haven't answered my previous points: A lot of those studies are for establishing discharge limits in natural waters. Not to mention there are a few on fathead minnows, guppies, and gamefish. Age in fish isn't just related to years but growth rate and size. A fish that's grown rapidly to market size is chronologically young but biologically older as it's at the point where feed conversion ratio drops and it's no longer economical to keep growing them. Anything that doesn't manifest in those eight months probably isn't ever going to manifest. Growing fish fast and big shortens their chronological lifespans so I don't know if this is really a good measure of success. What fish farms and hobbyists do isn't any different.

The vet at UC Davis told me that <150 ppm was fine but what do they know they only take care of the exhibits in public aquariums and aren't "experts."

A lot of those studies are for establishing discharge limits in natural waters. Not to mention there are a few on fathead minnows, guppies, and gamefish. Age in fish isn't just related to years but growth rate and size. A fish that's grown rapidly to market size is chronologically young but biologically older as it's at the point where feed conversion ratio drops and it's no longer economical to keep growing them. Anything that doesn't manifest in those eight months probably isn't ever going to manifest. Growing fish fast and big shortens their chronological lifespans so I don't know if this is really a good measure of success. What fish farms and hobbyists do isn't any different.

A lot of those studies are for establishing discharge limits in natural waters. Not to mention there are a few on fathead minnows, guppies, and gamefish. There's no scientific evidence of this though. And age in fish isn't just related to years but growth rate and size. A fish that's grown rapidly to market size is chronologically young but biologically older as it's at the point where feed conversion ratio drops and it's no longer economical to keep growing them. Anything that doesn't manifest in those eight months probably isn't ever going to manifest. Growing fish fast and big shortens their chronological lifespans so I don't know if this is really a good measure of success. But it is exactly what fish farms try to do... What is water quality? Why are we focused on nitrate which is only one of three nutrient cycles? Cleaning filters might actually be more important than changing water. A lot of people do leave the hobby and I think the peer pressure over nitrates and water changes is part of it.

Yeah, it's actually 44.3 vs. 443 mg/L nitrate once you convert the units. For 8 months. I don't think anyone is hitting 400+ for months on end. I'm now actually more concerned about dissolved organic carbon: https://www.sciencedirect.com/science/article/abs/pii/0144860988900064 It takes around 1,000 mg/L nitrate-nitrogen to inhibit growth in tilapia. Here, levels of DOC 125 times less were doing it. Not to mention there's a strong correlation between organic waste and disease but not with nitrate. The control group in this study experienced spontaneous denitrification hence the low nitrate value. What I'm afraid of is that organic waste trapped in filters/substrate continuously break down and release DOC and frequent filter cleanings, not water changes, are needed. That means that people doing water changes every week and cleaning filters twice a year have it backwards. It requires several thousand dollars of equipment to test DOC so it's going to be awhile before better technology lowers prices.

There just isn't scientific evidence to support the hobby's 40 ppm recommendation. Amphibians and some invertebrates seem to be more sensitive. There's a dramatic difference based on life stage though. Eggs and larvae/fry are the most sensitive. The papers discussing where to set discharge limits have to consider the most vulnerable life stage and species since they have an entire food chain to protect. Young life stages don't produce enough methemoglobin reductase that reverses the effects of nitrite in the blood (fish swallow nitrate-laden water which is then converted to nitrate in the digestive tract). That Camargo paper is usually the first that Google spits out. It relies on the discredited Kincheloe 1979 study for some of its lowest numbers. Later studies attempted to replicate the results but the numbers they got were several magnitudes larger. https://pubmed.ncbi.nlm.nih.gov/16916038/ This seems like a good time to point out that nitrate-nitrogen is nitrate * 4.43 so if the EC20/LC20 for a particular species is 1,000 mg/L nitrate-N it's 4,430 mg/L nitrate. EC20/LC20 should be lower than LC50 so the acute toxicity levels for fish are in the >4,000 mg/L nitrate range. No normal aquarium is going to subject fish to a chronic level of nitrate 10% of that. And you can see why fussing about 20 vs. 40 ppm isn't important. I've spent more time reading nitrate toxicity papers than studying for graduate level courses. It's become a hobby now and every few weeks I search for any new papers on nitrate or oxygenation.

There are plenty of scientific studies on nitrate toxicity. The 96-hr LC50s are in the 4,000-8,000 ppm range. Ten percent of that is considered OK for chronic exposure. And indeed salmon have been kept at 443 ppm for 8 months with no ill effects (they even performed blood work on them).

Nitrate is so non-toxic that you basically don't have to test let alone worry about 20 vs. 40 ppm.

Excel is the primary suspect. It's fish poison, after all.

Hanna does make multiparameter meters but they're expensive ($1,000). Other manufacturers make them as well so it's certainly possible. It's probably just cheaper/easier to make individual meters. And people can save money buying only the ones they need. One thing I don't like about Hanna is that they use the Nessler ammonia method which no one uses anymore. Also, Hach's chromotropic acid method for nitrate is probably the cheapest accurate and reliable nitrate test.

Nitrofuran is said to be unstable in water and also photosensitive. Kanamycin is apparently stable in water hence the every 3 day dosing. There's also microbial degradation. For example, bacteria will consume sodium thiosulfate. I'm not sure about other dechlorinating chemicals but I wouldn't be surprised. You can find studies or data on the persistence of most chemicals in aquatic environments thanks to all the environmental pollution research.

Nitrate isn't volatile.

When I deep clean I remove bio media from the tank. The times I put the media (plus a bunch of gunk) in a bucket the dissolved oxygen levels dropped pretty fast. YMMV, of course.

Nitrate is so non-toxic that being able to distinguish between 20, 40 and 100 isn't necessary. I don't even test for nitrate because I would have to stop changing water for months to reach toxic levels. Organic carbon, on the other hand, is much more dangerous and appears to require frequent filter cleanings to control. Water changes alone are probably insufficient.

Most current sensor tech requires calibration every 1-2 hours (ammonia, nitrate). Nitrite sensors are quite rare and it seems only one company makes them. The three ammonia standard solutions required for calibration can be contaminated by atmospheric ammonia. There's always research on new sensor technology and truly reagent-less sensors for aquariums will probably be available in a few decades. There's also colorimeter/spectrophotometer technology which uses a machine eye to read colorimetric tests. That you can get now. It doesn't require frequent calibration.

https://www.hach.com/colorimeters/dr900-colorimeter/family?productCategoryId=35547203827 Cheaper on eBay especially older models like the 890 which can perform all the same tests but just doesn't have USB and automatic logging of results. https://iorodeo.com/products/educational-colorimeter-kit?variant=12262607558 http://colorimeter-wiki.iorodeo.com/

Columnaris is everywhere. Even if you managed to completely eliminate it from your tank your new fish will reintroduce it.