API ammonia test kits and brackish water - which card?

[soggydrysuit]

Just wondering at what sg do you stop using the fw card and use the sw one when testing for zero ammonia with an API liquid test?

I'm at 1.006 with my change water which I mix up over 24 hrs (with heat and aeration) in a 20g tank. Last night I had a result that looked slightly greenish with a slight precipitate that looked more like a zero marine reading than the yellow fw. Or a 0.25ppm fw ammonia reading.

The tank may just need a good rinse and scrub, though. Didn't use the water...

Any ideas would be welcome!

[RTR]

That is a question best answered by API. They should be aware of the proper ranges for their tests. but I don't remember having seen such published.

Water of hydration is the issue for most kits, but the curves do not necessarily match from one test type to another (the chemistries are different), nor from brand to brand (again, the chemistries are likely to at least somewhat different). There is no sharp dividing line, the errors introduced are gradual changes with density/specific gravity. There could even be smaller variation between brands of marine mix.

[soggydrysuit]

OK, thanks RTR, appreciated. I'll contact them in any case - might be useful to know when to swap cards.

I wondered if that was a grey (green) area... I've scrubbed the change tank out with a new filter sponge, it was dirty to an extent. I'll try measuring ammonia again tonight when the salt has had a chance to dissolve and settle down.

It's my first brackish aquarium - for the Celon puffers

[RTR]

The error from one card or the other is likely to be consistent. That means that what you read will not be a real (read as: valid) number, but it should be reproducible. If the company provides you with a fudge factor (the best would be the curve of their results), you can guesstimate pretty well.

The very nature of colorimetric tests not machine read is a decent guestimate.

[Ditka]

If you do find the solution to this conundrum please post it here as i am wondering the same exact thing!

[marksrush]

I have emailed API and presented them with this question. I'll post what they tell me when they respond.

[soggydrysuit]

I'd e-mailed them too. So will also report back - wonder if we are told the same thing?!

Did an ammonia test on the scrubbed out water change tank with a new brew in. Same answer. Still pale green with a green precipitate but maybe not as dark as the zero on the marine card. Not the fw 'pale straw' colour either.

I don't get a precipitate with the fw tests, no matter the ammoia level. I always do with the marine ones - maybe that's a clue! Somewhere between as RTR says.

Whatever this reading is, the puffer tank is the same so I'm hoping it's the 'new' zero for my 1.006 sg. (Going to 1.008 with the next change tankful).

Just wondering when I get to my target sg of 1.018 if I should make up a set of standards of known ammonia concs, take a photo then laminate my own test card? Probably not worth it that high though - not much difference from the marine sg. Might be more use lower down the brackish scale...

[soggydrysuit]

Still no resposnse from API

[soggydrysuit]

Here's the response...

"Thank you very much for contacting us regarding our products. All of your comments and questions are valuable. We use your feedback to create the most effective line of aquarium and pond products available.

Andrew unfortunately you will have to estimate using the freshwater color cards for a brackish tank as the salt water colors are not as close to the correct readings as the freshwater color cards are. They will not be 100% the same color but they should be closest with the freshwater kit and its corresponding color cards."

[RTR]

That is not awfully helpful, is it? But the water of hydration increases throughout the range of BW, so the colors should be well off from FW.

Did you specify what your specific gravity is in your note to them? If you did, we are stuck.

[soggydrysuit]

Hi RTR,

I specified 1.006 sg, at the time...

I tried making up 2l of new salt water at the same sg as the puffer tank. 1.006 sg. My result was 'slightly green'.

This matched the puffer tank itself and the water change tank colour.

And the tap water was 'pale straw'.

Do you think they would pay us to calibrate it for them?!!

Much closer to the marine card, in my own opinion....

[RTR]

I love the idea! Suggest it to them, but don't hold your breath!

[Dynamite]

I have been wondering the same with my brackish tank that i will be setting up starting on friday, anyways i have no idea if i need to go out and buy a sw test or just buy freshwater(as i need to buy new new ones)

[soggydrysuit]

Well, with the API liquid test I've been using you get both cards in the one box with a test tube and the solutions - it can be used for both FW and SW.

Maybe my prob doesn't happen with another brand that can be used in fw and sw, but I think it might just because of the salt added to the water (see RTR's comment). Not fw zero ammonia colour, not sw zero ammonia colour but somewhere in between. My tapwater is 'pale straw', my 1.026 sg sw is the 'browny green' on the sw card.

When I can, I'll try to calibrate with different ammonia concentrations and salinities then line 'em up and take a photo. Got enough tubes to do one sg and four ammonia levels at once. This if I feel like wasting the chemicals but I'd like to prove to myself that I'm not getting a real ammonia reading...

[Brandon8521]

i would love to see some sort of calibration of colors for a mid brackish tank..... i have a sg of .015, i use api fw and sw ammonia tester..... my tank just crashed and im haveing to recycle it i havnt cycled a bw tank b4 since i slowely converted to brackish from fw..... its really hard to tell which one to use and even with my rather high sg my colors still show the bright almost neonish green from the fw cards rather then the darker earthier colors of the sw card... i would love to see what results you get with your calibration when you get the time.