Backyard Aquaponics
A place to discuss aquaponics

What do you guys use for the nitrate test kits? I use the API version. Is there another kit out there that works faster? Kind of a pain putting 20 drops in the vile when the kids are pulling on your legs making you miss count!

I use the API kit

Follow the instructions precisely or your readings may be wrong

After awhile you will get a feel for how your system is going and testing frequency will reduce

I test my system about once a month now

If your fish are eating a lot and you only have little plants then obviously your nitrate will climb quickly

Keep your nitrate under control as too much will trigger deficiency of other nutrients

This is one of the skills in aquaponics

Managing Fish feed / Plant ratio to keep your system sort of balanced

I don’t have any issues with the kit i’m Using. It’s always very accurate. Just wondering what other people use and if they are faster.

I like the Sera ones a little better. A bit more complicated but easier to read I think.



With API I’ve had trouble getting accurate results on NH3, ‘trites, and ‘trates when the levels are much higher than the top range of the test. I had ‘trites at 200ppm and the API showed 1ish. Sera showed 5+ (top of the range)

I do like how API has more granularity inside the range though.

Does chelated Fe(Fe-EDDHA) affect the reading taken by a nitrate test kit?(Due to the red coloration)

Probably not normally but it depends on the type of nitrate test kit and how much Fe-EDDHA you're adding to your system water. If it's causing the water in the test tube to look red before you've added any test solutions then I'd say that it's affecting the reading. I'm still using up a different type of iron (by spray application) so someone using the Fe-EDDHA version will probably have more insight on the levels they use and if it affects their readings.

I straight up can’t get the api test kit to work. Yes, I follow the directions. I use a stop watch to make sure I am doing it right.

First 10 drops and the color turns to about the 5ppm orange. 30 seconds of shaking, 10 more drops, 1 minute of shaking, 5 minutes later... still the same orange.

Tried that on samples diluted 19:1 and 39:1. All the same orange as the undiluted sample.

Meanwhile Sera is showing I have 25 ppm on the 39:1 sample. So 1,000 ppm overall.

Shit is killing me. I don’t know what to believe.

Hmm, well you might get some information by comparing the API and the Sera test kits on a sample of some other water, like your tap water or another AP system (or some other water with some nitrates). At least you'd know if they give you roughly the same reading when you know they should be. Other than that my only question is why would you need to dilute the samples so much, are they from somewhere other than the AP system water?

It's my AP. Sera test kit is showing 'trates are off the charts if I don't dilute it.

API always 5ppm. Weird thing is it reads exactly the same no matter how much I dilute it.

I just did a test with API on distilled water and got 0, so there's that at least.

I'm sure you're doing it right but just in case...

You're definitely adding 10 drops from the solution #1, and then from solution number #2 right? And vigorously shaking the solution #2 bottle before adding the drops?

I do precisely as shown in this video (and in the instructions), with a stopwatch.

https://www.youtube.com/watch?v=XWxbdx3BHqs

And no chance of the kit being out of date, or having been degraded somehow by sunlight or temperature?.. It's certainly strange how you're getting those readings

I think there’s something in my water that is interfering with the test kit accuracy. My under sink water filter removes chloramines, so I’ve been using that. But recent tests (in another thread) lead me to think it’s some sort of contaminant in the water itself.

SALIFERT!....with Sera a distant second...API in the bin.

Sorry to bump an old post but I think many here could benefit. I have only been on this forum a couple of days and all my posts have all been nitrate related but at an environmental scientist/experienced aquarist with no aquaponics experience, advise about water chemistry is about all I have to offer this wonderful forum at this stage.

Salifert all the way! There are inherent issues with testing for nitrate via titration but I have found Salifert to be accurate within 10%. Tried and compared all the hobby titration kits and it is by far the best. I'm not a API basher and their ammonia kit is quite good and nitrate kit is OK, but the nitrate kit is just terrible.

Since nitrate concentration within certain parameters are critical for both fish and plants, and because it can to an extent be used as a proxy for other nutrients that are even more difficult to test for, I highly recommend making reference solutions at say 20mg/l, 50mg/l and 80mg/l as a starting point. Dissolve KNO3 in distilled water and you have known nitrate concentrations- test the solutions with your test kit. If the reference solution is 50mg/l but your interpretation of the test comes out at say 80mg/l (titration tests tend to over estimate rather than under), then a bit of mental gymnastics is required to shift your interpretation of the test colour.

Shit is killing me. I don’t know what to believe.[/quote]

Don't believe any of it. A reference solution is your friend