Seachem Nitrate Test kit with RO water - weird result?

[Jack L]

Hi,
yes i did already google it, i didn't try reaching seachem tech support yet.

if any of you use seachem nitrate test kit, have you ever done it on RO water? and if so did it read positive for nitrates? i was expecting 0, but it reads 10 or so( i say "or so" because the chart is uberlame) but i can tell it is NOT zero. i test my softened water it comes out zero.

wondering if RO water makes the test not work.

thanks

[DJW]

Do you have some nitrate-removing resin in your softener by chance? My crummy well water has 45ppm of nitrates and the RO removes about 92%, leaving 4ppm. My nitrate tests make sense but yours don't. If the RO filter was removing 90% of the nitrates your tap water would have 100ppm right?

[Jack L]

the softener has sediment filter, carbon filter, then resin beads.

the water that goes through the RO system has already gone through the softener

which lead me to the thought, without anything to react with in RO water....the seachem kit malfunctions

[DJW]

It is still mystifying though. If it did the same thing twice, showing zero before the RO and 10ppm after RO, how can that be explained?

I use the API for nitrates but thinking about getting the Seachem ammonia test, it looks more accurate at low levels.

[Jack L]

It is still mystifying though. If it did the same thing twice, showing zero before the RO and 10ppm after RO, how can that be explained?

I use the API for nitrates but thinking about getting the Seachem ammonia test, it looks more accurate at low levels.

it might be better for testing VERY low levels, i.e. if you get no color versus APIs yellow for zero

when i test RO water is when its shows nitrates, i expected that to be zero nitrates.
my guess is the reagents have noting to react with in RO water and produce erroneous results.

i'm going to next test RO water with minerals added back and see what i get, as well as see if seachem will respond to email

[DJW]

To get my daily dose of nerdiness I looked up the chemical reactions that take place when you test for nitrates. The first reagent contains particles of zinc metal that quickly reduce the nitrate to nitrite. The second reagent contains sulfanilic acid and a colorless pre-dye called dimethyl alpha napthylamine. Nitrite reacts with the acid and this reaction changes the pre-dye to red. The more nitrite the redder it gets.

The test result includes whatever nitrite was present in the water sample, but since nitrite is always present in much lower concentrations (you hope) than nitrate, the nitrite has a negligible effect.

I was not able to find any mention of results being skewed by low or high mineral content. I'm not much of a chemist but the chemical reactions in the test don't appear to need anything from the water except the nitrate itself.

[Jack L]

To get my daily dose of nerdiness I looked up the chemical reactions that take place when you test for nitrates. The first reagent contains particles of zinc metal that quickly reduce the nitrate to nitrite. The second reagent contains sulfanilic acid and a colorless pre-dye called dimethyl alpha napthylamine. Nitrite reacts with the acid and this reaction changes the pre-dye to red. The more nitrite the redder it gets.

The test result includes whatever nitrite was present in the water sample, but since nitrite is always present in much lower concentrations (you hope) than nitrate, the nitrite has a negligible effect.

I was not able to find any mention of results being skewed by low or high mineral content. I'm not much of a chemist but the chemical reactions in the test don't appear to need anything from the water except the nitrate itself.

Thanks Nemonic, you nerdiness prompted me to retest all them again.

tap, softened, ro
with api and seachem

something was wrong with my first testing, not sure what.

this is what i get now, testing carefully

tap = 30ish per api and seachem
softened = 30ish per api and seachem
and r u ready......
ro = 5 ish per api and seachem

i'll upload some pics later. color matching to number is subjective, but the difference in color is not.

i guess i can forget about using tap or softened water for the Ds

[DJW]

Glad you retested, that was strange.

I have the same problem with high nitrates, so I mix about 95% RO with the well water. Sometimes I want more mineral than this mix gives, for growing fish, and use homemade or Equilibrium. I have river water as a possible source which is perfect water except that it is cloudy and cold in the winter, and probably teeming with parasites.

[Jack L]

Me too, thanks

I was thinking that RO would be zero. I am pretty sure that when I tested ro before switching to it, it did read zero. But maybe the city is using different well now. Maybe I will get seachem safe to add to the RO, prime does lower nitrate, at least per my testing. I want to start with zero not 5-10

I currently use alkaline and acid buffer and equilibrium to my RO water

What do you mean " homemade "

[DJW]

I have never used Safe or Prime since the well water has no chlorine or chloramine. Seachem says that it detoxifies Nitrate somehow. My water starts out hard enough that after RO there seems to be enough buffering going on to give the water a stable pH, so I don't have to fuss with the pH at least.

It seems kinda silly to run water through a RO filter and then to reverse the reverse osmosis by adding stuff back. If it wasn't for the nitrate pollution I wouldn't bother with it.

I made a batch of minerals once... its a pain because some of the ingredients are hard to find. Now I just buy it. Mine only included the main parts: Potassium from potash, calcium from plaster or paris, and magnesium from Epsom salt. This was for a heavily planted tank with Rams. Like any other DIY stuff that the fish are exposed to, you have to worry about additives.

Here is a link to a recipe:

http://forum.simplydiscus.com/archive/index.php/t-103814.html