confusing ammonia test results

[Solarris]

I have been cycling my 55 gallon tank and for the past 4 weeks or so I have been getting a consistant reading of 0.25 ammonia even though I was past the time that everyone else says it takes to cycle a tank. This morning I tested and it was 0.25 again. I did appox a 40 percent water change then a few hours later tested again and it was still at 0.25. I have been using a Red Sea test kit but last week purchased an API ammonia test kit so I decided to check the results with that. The API is showing a very definite 0 for ammonia. Has anyone else ever had discrepancies between brands of test kits or know anything about one being more accurate than the another?

 

[dkpate]

I prefer API, as I believe most people on here do. I would go with the API reading.

 

[cabezon]

yes. test kits vary.

so, what ammonia source have you been using to cycle?

 

[Solarris]

I have 6 goldfish in there now. I was doing pwc's until I started getting consistant readings of 0.25 ammonia. They have been doing very well with no problems at all.

 

[IslandHopper]

If you've also seen an extended Nitrite spike .... then drop to 0 (or near 0)... and measurable NitrAte readings, You can probably assume your tank has cycled and the test reading was off.

That said... 4 weeks may be enough to complete a cycle, but it's also not uncommon for it to take 6 or more weeks.