Salifert Nitrate Test Kits

[jwright]

Does the salifert Brand Nitrate kit test positive for nitrates for freshwater?

I have a 32 gallon rubber maid trash can that I fill with RO water and use to mix my saltwater? This water always tests 0ppm for nitrates?

But my 32 gallon rubber maid trash can that I use for RO fresh water top offs always tests around 5ppm for Nitrates using the same kit. I have rinsed and rinsed and well you know the drill. Both cans were new never had garbage in them. At any rate that is why I ask the question. Nowhere in the materials on the box does it specifically say for freshwater use so maybe it isn't. I didn't find the web any more helpful on the subject either.

Thanks In Advance.

 

[TCTFish]

I always found it best to use test kits for what they are intended for. Saltwater for saltwater and freshwater for freshwater. I'm not sure how much of a difference if any salt makes with test elements, but the differences in the readings you are getting may not have anything to do with the test kit. If you leave the water sitting and exposed to air, anything landing in it can create a sort of cycle mode and end up with a little bit of nitrate. You can keep the water circulating with a water pump to keep it from stagnating if it's hanging around for awhile before use.