Test strip vs. Bottle water tests??

Question

What is more precise on measurements?? When I tested my Nitrates correctly with shaking the bottles like they are supposed to be I got a tough to read somewhere between 40 - 80. Then I did a test strip water from the same tank and got a reading of 20 on the test strip? Which one should I depend on more?

Just for kicks I took a sample before and after I did a 20% water change on a 120 gallon tank. I'm sure the water had less nitrate after because I know the water has somewhere around 7 nitrate in it. Yet the tests showed almost the same somewhere around 40 - 80. When looking at the card the 40 and 80 look the exact same color to me so it might have started out at 70 then whent down to 50 after??

Thanks for help!

Answer 1

The bottle of drops method is more accurate IF you be sure to hold the bottle straight up and down and allow the drop to fall directly into the water. If you don't do this it can and will throw off your readings. If you are willing to invest a little, the electronic pens are the most accurate measure assuming you keep it maintained and calibrated correctly.

Be sure to keep your testing materials out of the light as much as possible.light can damage strips and bottled solutions as well as fade the scales you use to compare colors. Another reason to invest in the electronic pens in my opinion, but invest in good pens, not the cut rate pens some aquarium suppliers carry. Get the good ones from a lab supply warehouse.



MM

Answer 2

The liquid test is USUALLY more accurate than the paper strips. I say "usually" because there are things that can go wrong with both methods.

First, check both kits for expiration dates. If the chemicals are old, this can throw your results off. And don't depend on when you bought or opened the kit - these can sit on store shelves for years, although good stores will get rid of them before the expiration. There's also one company that will replace chemicals for you if you bought a kit after it expires.

Second, make sure you follow directions exactly and handle the strips/collecting tube correctly. As MM said, you need to hold the dripper bottle perfectly vertical - this can change the size of the drops, therefore your results. Hold the test paper only by the end without the "pads". And be careful how you collet the sample - you don't want tank water flowing over your hands into the tube or "you" can affect the results.

As for your before-and-after test, these results could be correct. If your nitrates were high (80) and you replaced 20% of the water you would still have 60 (although I wouldn't want to be one of the fish in your tank if this was the case!). Another possibility - have you checked your water source for nitrates?

You could also take a sample of your tank water to a fish store in a clean container and have them test the water to see how this compares to your results.

Answer 3

First of all you have to remember tap and bottled water can contain upwards of 15% nitrates. If you live in NY LA or Chicago it can be as high as 20%

Strip tests are not as accurate as water tests. A good water testing kit will run you aroun $20-30. A cheap one around $15.
40 ppm for nitrates isn't bad. You will never have 0 unless you have idiot test strips which start at 40 as reading 0 since it is a standard safe level. (Not all strips are this way mind you)

Sounds like you need to get a better water test kit. If you are matching colors for readings, you need a better test. Could you imagine if you were color blind?

Test your tap water or the water you are using for your tank. See what the neutral readings are.

If you don't trust your eyes with the color chart, get better test strips. Your range should not be between 40-80.

I would do a test with the strips, get a reading.....remember to let the strip dry and read it again, do a water test, then take a sample to the local store and have them test it. See which test kit is more accurate for your use.

Good luck.

Answer 4

Liquid tests are way better and more ecconomical. The paper tests are created for convenience, not accuracy or economy. You get 25 tests for the average paper test at $14 dollars. You get at least two years worth of tests for $35 with the liquid ones.

With the paper test, your nitrates are probably way outside the range of accuracy. They have a minimum & maximum value that they can test for & its usually specified. When I first started keeping oscars it was like that... the test showed 40 ppm nitrate no matter how much water I seemed to change. I dumped all of the dead plants in the tank & started doing more changes & it came down.

Don't waste your money on paper test strips especially if you have a nice 120 g tank.

Answer 5

I'd say the test strip because they can also mesure all the other stuff in the water. We used to get those strips that tell you everything and a color coded

Answer 6

Wow, that's high. The liquid tests are better. Strips are notoriously wrong. Its partially because (exposure to air, light, your fingers, paper itself, ext.) alters the chemicals a bit over time.

Answer 7

yes, lots of stuff is different, people just like you began trying lots of different methods and found some that work better than what the scientists were able to do in their tanks. as far as what else, yes, lighting improves every year, calcium reactors, dosing systems, monitoring systems, additives, dozens of different designs for every component like protein skimmers,filters, etc. different methods of running a tank, FOWLR, Reef, Berlin, Jaubert, etc. etc.

Answer 8

Here is a site that reviews the aquarium test kits

http://saltaquarium.about.com/od/prtestkits/Water_Test_Kits.htm