Impossible water parameters?

[Wulfonce]

I left my 20g community tank alone for a whole month while I went on vacation. I used an auto feeder in my absence and told my buddy to come over once a week to make sure everything's going alright.

When I came back the first thing I did was test the water. The results were:
Ammonia 0ppm
Nitrite 0ppm
Nitrate 0ppm
PH 7.6 (stable and same as always)

How can this be?

There are 16 fish in there that were eating and producing waste for a solid month. I can understand ammonia and nitrite being 0ppm but how can the Nitrate be 0ppm? The only way to get rid of nitrate is to do water changes correct? And if there was no bacteria to start with (which Isn't the case) the test would show high ammonia right? I talked to my buddy and he said he never once did a water change.

How is that possible

 

[lighthouse39183]

How heavy is the bioload on the filtration and how much filtration do you have on the 20g? If you have any live plants, then that might also be a contributing factor. Sixteen small fish that don't produce a lot of waste and all are not going to cause the same results as 16 that produce massive amounts of waste.

 

[Bderick67]

I would say that unless you have a tank full of plants that the results of your test are incorrect.

 

[ProblEmZ]

I'd do another test atleast the next day before i really freaked out. This is before a water change correct?

 

[lighthouse39183]

Actually Bderick67 beat me to that. I was thinking about the results and you probably need to check the expiration date on your test kit. What kind of test kit do you have?

 

[Wulfonce]

How heavy is the bioload on the filtration and how much filtration do you have on the 20g? If you have any live plants, then that might also be a contributing factor. Sixteen small fish that don't produce a lot of waste and all are not going to cause the same results as 16 that produce massive amounts of waste.

I have a standard 20g HOB filter. The 16 fish consist of:

(5) 1-1/4" neon tetras
(5) 1-1/2" White cloud minnows
(1) 2" molly
(4) 1" corys
(1) 3" cory

Others in the tank:
(1) 2" ghost shrimp
(12) molly fry

There are no real plants in the tank

 

[lighthouse39183]

Yea, I think you have a problem with your results on the test. I don't know how much the auto feeders dispense but it seems like you should at least have some nitrates showing after a month. What type test kit do you have?

 

[Wulfonce]

I'd do another test atleast the next day before i really freaked out. This is before a water change correct?

I did the test before cleaning and doing a water change. I couldn't believe the results so I tested everything again and got the exact same results.

Actually Bderick67 beat me to that. I was thinking about the results and you probably need to check the expiration date on your test kit. What kind of test kit do you have?

I have the freshwater ammonia, nitrite, nitrate, and PH chemical dropper test kits from "aquarium pharmaceuticals inc." I bought them from Big Al's 2 months ago. I looked all over the bottles, boxes and instructions and I don't see anything about an expiry date. These kits have never let me down in the past. I test my tanks every 3 weeks and get fairly consistent results but nothing like this.

 

[lighthouse39183]

Those are the liquid tests, right? If you purchased them 2 months ago, they should be good, unless they had a long shelf life. Are you shaking the solutions before you add the drops to the test tube? I know the only one that says to do this is the second bottle on the nitrates but if you don't shake that one for at least 30 secs before adding it to your test tube you won't get a correct reading.

 

[Wulfonce]

Those are the liquid tests, right? If you purchased them 2 months ago, they should be good, unless they had a long shelf life. Are you shaking the solutions before you add the drops to the test tube? I know the only one that says to do this is the second bottle on the nitrates but if you don't shake that one for at least 30 secs before adding it to your test tube you won't get a correct reading.

The liquid ones, correct.

Actually I generally shake all the bottles for around 30 sec before testing. Your right though. I read the instructions and it only mentions shaking the 2nd bottle of the nitrate for 30 sec. But on the other hand I test every 3 weeks and have been getting consistent results... except for this time.