Nitrate Testing Accuracy (false high readings) & Water Change Implications

[RD.]

LOL, I stopped listening to Seachem reps a long time ago. IMO some are very good, some are a wee bit confused, or simply regurgitating what they've been told to say to hold the company line. Dr. Greg Morin, the head chemist & CEO of Seachem has always been very straightforward with me, even when he probably shouldn't have been. It was because of my comments to their reps on the Seachem forum, which were later passed on to Greg, that they changed some of their literature regarding Safe dosage rates. Greg also contacted me directly in regards to the change in dosage rates, and his comments regarding the issues they face with consumers was rather blunt.

My correspondence with John Kuhns was 14 yrs ago. I posted the following thread, which was later made a sticky here 8 years ago.

https://www.monsterfishkeepers.com/forums/threads/cost-effective-water-conditioners.309623/

I have no reason to question the research performed in the labs by John or Greg, nor would I, but clearly some of it required some clarification with regards to what can or possibly might take place in an aquarium containing fish, their waste, different pH values, etc. With John Kuhns I was mostly concerned with dosage rates, as some of the info from vendors at that time seemed a bit sketchy. Back at that time I had to order Cloram-X from the states, with only one vendor in the USA that would ship to Canada. (hats off to Randy Reed)

Obviously my testing pales in comparison to the equipment and procedures available to a qualified researcher in this field, but in my tanks, I used various kits testing for both chlorine, and free ammonia, before, during, and after tank refills, and I was always below detectable limits. I still have the free/total ammonia test kit, it was made by Seachem and came with a reference sample, and a scale from 0.0 mg/l - 3.0 mg/l. Overall total bush league, but 20 yrs ago or so when chloramine was new to the scene locally my testing and John & Gregs input certainly helped alleviate a lot of the concerns that I had.

 

[RD.]

Squint - did you read that entire paper? All I took away from that thesis is that there are numerous variables involved when treating wastewater with very high organic loads, and that there is a lot more work that needs to be done in this area. If you dig deeper, and some are even mentioned in his thesis, over the years there have been far lower dechlorination reaction times claimed by certain authorities , including NMED (2003) that claims the reaction time between free and combined chlorine and the sulfur iv compounds occurs between 15-20 seconds.

I don't think that we are anywhere near being able to compare what is taking place in a wastewater facility, and an aquarium.

 

[markstrimaran]

I live in farm land Iowa, my tap water is always, at the EPA, MAX. PPM. A great supply of a known ppm, to test for accuracy.

 

[Coryloach]

I also had to compare results with nitrate test strips we used in the field, and the pro quality strips from Fisher Scientific were usually very close

Hey Duane. I appreciate the experience and expertise but the water solution used to test in laboratory conditions is completely different from that of our fish tanks that has millions and billions of ions dissolved. Plus, each one of us has different water conditions in each tank. The nitrate test is skewed by other ions dissolved in the water and the nitrate reading is not consistent across, thus one's 10ppm could be totally different from another's 10ppm. And of course, the skill factor also comes in play. Some people don't test properly to get accurate results, but even then it is not a guarantee considering the "test" water is so different. Hence I think a conductivity(TDS) meter is far better way of monitoring water quality.

And although nitrate may not be acutely toxic to fish, it can create chronic problem, and be a stressor the leads to HLLE and other health problems as fish age.

Is there any paper I can read in regards to the above statement? Its not that I don't believe it. I am just not convinced that nitrate is the only issue, if it is an issue at the levels we have in the average non-overstocked, well maintained tank. How do you feel about dosing dry fertilizers such as KNO3? Would you differentiate to organic nitrate for example? There are many accounts of high tech planted tanks dosing excessive amounts of nitrate and having healthy and breeding fish for years....One major factor/connection between these set ups I find is the frequent water changes to maintain the plants healthy and free of algae(aim is at reducing not nitrate but dissolved organics)......However, nitrate is always on the high side compared to non-fertilised tanks...
I think organic nitrate, i.e. that produced in the fish tank itself, if measured adequately, is the smoking gun of far worse things going on in said tank.....The only solution in my view to long term health is preventing production of organic nitrate, as it is a consequence of high ammonia and high dissolved organics content along with very high oxygen demand, none of which will lead to healthy fish environment. And the only way I've seen so far in my experience, is to keep tanks on the lower stocked level....and keep maintaining the tank as if it was overstocked....

 

[thebiggerthebetter]

I definitely respect the science behind this and have some commercial experience measuring water params given we have a boiler system at work.

Thing is, given there's so much that skew the readings, this makes me want to change water in my tanks even more! lol. After all, it's not just because of nitrates we change our aquarium water. IMO, it's important to keep your tank water as close to the parameters of your source water as possible.

For me, I don't care that my API nitrate test kit still reads orange on day 7. I'm still doing a 50% water change at a minimum. There's a week's worth of bodily waste products, food being added to the tank, etc.. in there. Yuck.

Old school just a decade or two ago dictated to leave the aquarium water alone. There have been posts by those keepers where they stated they changed their water once or twice in 10 years. In particular with adult Synodontis eupterus living in the tank. But this is probably an exception. Normally people changed water quite rarely and made believe that aged water is the best water.

I am not saying I am an adept of the old school at all. I am citing this just for a stark contrast.

 

[nzafi]

Sometimes I wish I kept better records of my fish keeping. I start keeping piranha back in 1999. At that time the common practice was that only monthly water changes were needed and that 10-20% was sufficient. This is very different from these days. I left visiting the forums around 2003 and only peeked in once in a while until about 2011 when I became a daily visitor again. From 1999 to 2016 I kept a black piranha (rhom) for 17 years in a 75g tank feeding about 1-2 times a week with 10% water changes every 4-6 weeks. In 2011 I decided to test his tank water to discover nitrates were over the 150ppm mark and from then on I began a more regimental water change approach (50% weekly). He eventually developed HITH and died in 2016 after 17 years of keeping him. It is safe to assume he was living in water for 11 years with nitrated over 150ppm and even when I started the new regiment I could never get it less than 40ppm.

I am no scientist but that is an example where nitrates were not a factor. While he developed HITH in about 2013, I believe his eventual demise and cause of death was voltage leakage. Not until several more fish died or came down with disease was I able to discover my equipment was leaking voltage which was the same equipment I used with him.

 

[duanes]

I agree that nitrate is only part of the issue, but I believe high nitrate is a major stressor over the long haul, but just one of the many that aquarium life puts on fish. Most natural cichlid bodies of water, have little to no nitrate at all.
The high nitrate in combination with, too small of tanks (I consider almost all tanks so small) they contribute to stress for medium to large cichlids.
The combinations aquarists try to put together (such as more than 1 species of Parachromis, or others of the same genera in the same tank )you hardly ever find that in nature.
Along with the, too small a tank, trying to cram many individuals in that tank, that is really only the size of a rut in the road.....etc etc.
I could rattle off more, but I believe to no avail.
But add high nitrate to the others above, and I'm actually amazed that there aren't more "why is my fish sick(?)", or "why are my fish beating each other up?" posts.

 

[Rocksor]

For the same reasons I don't test for nitrates either. I use a conductivity(TDS) meter. If the tank's water measure has deviated from the tap's reading, then water has become more conductive, i.e. there's waste build up and water changes are needed to bring the reading back to tap water. I consistently keep tanks to tap reading in line, even after years of running the same tank....and for me this method has been the most efficient and reliable in terms of water quality, my happy and healthy fish being the proof for it.

But as R.D. says, in a reasonably stocked tank one large water change a week(50 to 80%) is enough to bring tank and tap water level with some exceptions from time to time. In a heavily stocked tank you need way more than that.....As a reference, I've got roughly 13 clown loaches, 9 adult denisons, 5 SAEs and a bunch rasboras, a few kuhli loaches, a few corydoras in a 240 G tank. I have humongous emerged plants that by the way are chronically nitrogen deficient. I do one large weekly water change. Other people, in the same tank volume would have way more stock......i.e. needing way more effort to keep tap and tank's TDS in line....

As for nitrates, it's worth mentioning that my tanks have never had much of a nitrate reading due to high plant mass. TDS(conductivity) however, increases if water changes are not done. People that have never used a TDS meter and rely on nitrate testing and artificial nitrate removal may be oblivious to their water quality.....because nitrate is not the only issue at play...

What is the TDS difference between tap water and tank water when you do a water change, and how much water do you change?

 

[Coryloach]

What is the TDS difference between tap water and tank water when you do a water change, and how much water do you change?

On the current tank the rise between water changes is negligent, up to 5ppm. This is largely due to the high emersed plant mass I have which has unlimited access to CO2 and light, only limitation is nutrients which come in the form of fish food... Stock is on the low side as well. See pictures of that tank below.

I still do between 50 to 80% water change weekly....That's to replenish minerals that aren't necessarily produced via fish waste, plus remove the types of waste which is not in a form available to plants/are not used by plants.....The maintenance workload is basically shared between me and my plants

Its worth noting that my set up is not a typical fish only set up, hence my TDS rise is negligent. But this is not the case in a fish only tank....You'll be battling tens of ppms rise of TDS each week, anything from 5ppm to above 60ppm depending on stocking levels. In fact, most people that buy a TDS/conductivity meter for the first time will find out that the difference between their tap TDS vs tank TDS has gone out of control over the life of the tank....If you've got no plants, only solution is very large water changes quite often, again depending on stock.

As far as nitrate is concerned, one can very easily test their tank for total nitrogen by introducing floaters. If they flourish, providing light is sufficient, then the tank has plenty of dissolved nitrogen in the water column at any given time...Its even easier with emersed plants in hanging pots because fish can't get to eat those plants, and surface movement can't drown them.....

In my current tank plants are chronically nitrogen deficient and that's how I know I barely have any nitrates these days, not in this tank. Regardless, for years I only monitor the TDS because if it rises, and you've got no plants, you most certainly have a rising nitrate trend as well...plus all the other waste...

The tank is a mini 240G indoor pond

My fish are my major indicator whether I am doing it right

 

[Coryloach]

Most natural cichlid bodies of water, have little to no nitrate at all.

And they are also void of any other minerals, i.e. extremely low conductivity/TDS....So the issue is not necessarily to do with nitrate levels, or just nitrate levels.

When one has chronically high nitrates, one also has chronically high ammonia production plus tons of dissolved organics of all kinds in the water column, and due to high nitrification and decomposition, the water is also very low on oxygen. What is the issue, then? ...the high ammonia production and low oxygen or high nitrate? In this same scenario TDS will be jumping through the roof....