Nitrate test differences

Caesra

New member
I am hoping to get a few inputs on how the different test kit companies come to their nitrate levels.

I have a strange issue going on in my tank system and am curious about test test kits. I am less concerned about the issue than understanding what is going on and why I get different readings.

First, I have always had this issue where different kits give different readings. I have had my water tested against two other sources using the same set of kits, seachem, API, and salifert, and some test strip (dont remember name). I get very different readings on each. I assumed some of the test kits were bad, which is why I took to different sources and had them tested against the same kits. Same (for each kit) readings came out of the tests.

Currently readings show
API: 25ish
Salifert: 2.5
Nutrafin: 60
Test strip: 20ish

As you can see I get radically different readings.

Other params:
Ammonia: undectable
Nitrite: undectable
PH: 8.2
Calc: 420
Alk: 7
Mag: 1300
Temp: 80
Phosphate: <.1

Why do I get such dramatically different results. It is my belief that the differences in the tritation method will be the key to understanding of what is going on in my system. Part of why I beleive this is since my issue began these readings have become more spread apart. Before issue the different test kits read more like

API: 10ish
Salifert: 10.5 (note this one is down in my current tests)
Nutrafin: 20
Test strip: 20ish

Quick overview of system (again...I am not focusing on the symptoms but trying to get to understand why the nitrate readings are so different.)

420g linked system, 180 mixed reef, 55g planted, 29 non-photo tank, 29g lagoon, 40g sump, 40g cryptic and 50g of Bangaii fry tanks.

Believed trigger event to the change was dosing vinegar (relatively low amounts...roughly 30ml/day. Some other minor changes occured during the few weeks this onset, but I don't think are the cause.

Noticed changes during vinegar dosing. All test kits read 0 Nitrate. Acro growth and monti frowth accelerated dramatically, LPS looked less healthy. Macro growth took off (with exception of chaeto..which stopped growing), micro algea growth changed from normal soft glass alge to a harder algea, more brown in color in parts of the tank. Coralline algea took off during this period too...growing at a rediculous rate like the Acros.

Event that triggered ceasing vinegar dosing: Monti's started dieing with tissue recession resembling nudi pattern (I don't believe was nudis, as several montis in close proximity to the ones that died are alive). All coral in the same family as procillapora began receeding rapidly, including my favorite which was almost a foot in size. =( note all of these corals were in excellent health at the start of the dosing.

Since stopping dosing the death has stalled, although the procillapora type corals are still receeding (very slowly at this point).

Normal micro algea growth still has not returned at this point. Macro growth is more normal and cheato is growing very slowly. While the acros are still seeming happy, the montis very rarely extend polyps. LPS growth appears to have stopped, but the corals are extending normally. (note all coral in the planted tank seem very happy..much more so than in the other tanks).

Fish have been fine during all of this.

I know most people are going to say change water to solve the issue, but again I am most interested in understanding what the differences in test test kits are.

Thanks,

C
 

RegalAngel

New member
I had a Salifert NO3 kit with Exp. 02/12.... checked it against a 100ppm NO3 cal. sample....got 25ppm!

I have used the API NO3 with good results...it should agree closely with the Salifert. If Salifert is way lower then I would suspect the Salifert kit is bad.
 

Randy Holmes-Farley

Reef Chemist
Premium Member
The bottom line is that many nitrate test kits are often grossly inaccurate. Many kit comparisons have been run over the years, with results on the same tank water sometimes running from undetectable to 100 ppm. :(

FWIW, I almost never measure nitrate.

I'm sorry to hear about your deaths. I'm not sure it is vinegar related, but it might be. I've never had any issues with it, but I do not keep those same corals. Perhaps they already had a low level bacterial issue that because worse on organic carbon dosing.
 

tmz

ReefKeeping Mag staff
Premium Member
30ml of vinegar on a 420g system is a very light dose.

IME, the salifert and api test kits cross check pretty well.>25ppm NO3 wouldn't cause those issues either, ime with those corals.

Sorry for your troubles and losses.

I'd take a hard look at alk. If it swings or drops much below 7 it could cause the problems you've described. How about salinity?
 

Caesra

New member
I had a hard time beleiving that it is related to the vinegar dosing as well, and the dosing was very light. Was dosed in the kalk mix. The alk and calcium did rise during the dosing, but slowly and not terribly high. We went from 425 to 475 calcium and from 8 to 10 alk. This occured slowly over two weeks or so.

The levels have dropped down because I have stopped doing any real dosing outside of plain kalk.

The onset of this did look like a bacterial bloom, but with such a low amount of vinegar I have a hard time beleiving it. both the montis and the procillapora had a brown algea (bacteria?) following right along the trails of death. I assumed from exposure of the skeleton..not the cause of death.

Salinity pretty stable at 1.025..I had a slight swing during a water change to 1.023. My water changes occur over 5 hours or so (slowly exchanged via pump).

As I mentioned the very odd thing is the total micro algea change. Light green algea on glass, to a light brown. Currently I still have very little green algea and what does grow is not light and fluffy, but thick and encrusting.

Hard to explain.

Only other thing I can think of is somehow a toxin got into the system, but that wouldn't cause the massive change in micro algea growth (wouldn't think so).

BTW...it is almost a month since I stopped dosing the vinegar and the tank has been through two water changes (I do roughly 15%, as that is all I can mix at a time).
 

Caesra

New member
I had a Salifert NO3 kit with Exp. 02/12.... checked it against a 100ppm NO3 cal. sample....got 25ppm!

I have used the API NO3 with good results...it should agree closely with the Salifert. If Salifert is way lower then I would suspect the Salifert kit is bad.

As mentioned, the kits were verified against new kits at the LFS and local reefer. Each kit of same brand gave the same results. Mean salifert's matched level, API matched level, etc...

LFS API=My API
LFS Salifert=My Salifert.
 

Caesra

New member
Can anyone explain why I get such radically different nitrate results? As I mentioned, each kit is giving pretty widly different results (one showing 60? =/)

I could buy bad kits if the results had not been verified against another set of test kits.
 

Randy Holmes-Farley

Reef Chemist
Premium Member
Not sure what you mean. If two kits give different results on one water sample, one or both is inaccurate. It is very common with nitrate kits.
 

Caesra

New member
Example

My test kits

API: 25ish
Salifert: 2.5
Nutrafin: 60
Test strip: 20ish

Water taken to LFS on same day

API: 25ish
Salifert: 2.5
Nutrafin: 60
Test strip: 20ish



Water taken to friend on same day

API: 25ish
Salifert: 2.5
Nutrafin: 60
Test strip: 20ish
 

tmz

ReefKeeping Mag staff
Premium Member
Nitrite presence skewing results for nitrate high on api and nutrafin, perhaps? Tests for nitrate and nitrite are colorimetric; in some nitrate shows up as nitrate. I know you posted 0 for nitrite but I might check that again.
 

Caesra

New member
The tank is not cyclying...well shouldn't be. The tank has been setup for over a year and is pretty well established. Although the tank system has been under increasing load due to the breeding activity, but the increases have been slowly occurring.

The idea that it kicked into a cycle is interesting.... I will check and post back later.
 

Caesra

New member
Well the Nitrite test just showed me .25 probably less...Not the same reading as I got last time, but I certainly would not think enough to throw the nitrate readings way off.

Not sure why I would have any (I am suspecting that kit is going bad :spin1: )

Still have a tough time with the idea of a cycle kicking in, even though the system is under a pretty good load.

roughly 60" of adult fish and 70 fry/juvies are in the system now. So feeding is a bit on the high side. But the system has about 400lbs of LR and 500 lbs of sand/gravel and heavy skimming.

In process of finishing setup on breeding system. So that load will be removed from the system soon.

I would just like to figure out what going on before I have lost all of the procillapora.
 

Randy Holmes-Farley

Reef Chemist
Premium Member
A little nitrite can read as a lot of nitrate with some kits, like Salifert. The reason is that the nitrate kit converts a little of the nitrate to nitrite for processing in the nitrate kit, so there is a multiplication factor, although I'm not sure what it is exactly.
 
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