False No3 reading

[tnnlynch]

Some background:
I was out of town for a week and so went with a bit longer than a week with a water change. My brother was watching the tank and replaced the evaporation with RO water while I was gone but added no ferts. All previous water tests I have been doing have shown a very low NO3 reading (0-5ppm) inspite of my dosing using the EI method. The water test I did before I changed the water in the tank showed around 20ppm NO3. I did my 40-50% water change and added 2 generous tsp of KNo3 after the water change and my test shortly thereafter showed 0 ppm NO3. It never occurred to me before but my declorinator (PRIME) promises to "detoxify nitrate and nitrite". Adding Prime to a test solution of NO3 also caused it to show as 0 ppm.

My question:
Is prime removing the NO3 from the water so that my plants cannot use it or is it merely hiding it from my testing?

Thanks
Tom

 

[Tom Barr]

Re: False No3 reading

Greg from SeaChem said no.

The reduction of NO3, is strong enough to unbind the potential chelators/complexs, generally asorbic acid is used, in place of my test kit method, Cadium reduction(which we send back to have it recharged rather than tossed out!).

It(Prime) detoxifies it, it does not destroy or reduce it.
Most test kits measure both bioavailable(very often the inorganic fraction) and organically bound forms of the nutrient.

Regards,
Tom Barr

 

[srozell]

Re: False No3 reading

In a heavily planted tank is there any point to detoxify nitrate and nitrite?

 

[tnnlynch]

Re: False No3 reading

Tom B:
Interesting. I wonder why it caused my test solution to read 0 ppm? I'll have to repeat that test to see if I has the same effect. I added prime to a test tube of water that I had already tested. When I did that the color returned to clear. Is that an invalid test? Too much prime considering the amount of water & NO3 in the test tube?

srozell:
I use prime to treat my tap water for both my planted and non planted tanks. It has always worked well for me and using one chemical made it easier on shelf space.

What do you use to remove Chlorine/chloramines?
Thanks for the input,

Tom

 

[Tom Barr]

Re: False No3 reading

I use amquel, Greg and I had this discussion years ago.
Prime should not influence the kits, nor affect things different than Amquel, the only difference is that Prime is more concentrated and stinky!

I do not know what causes your test kit to measure that.
I do not trust test kits much as it is.

Try testing about a day later rather than immediately after the water change etc.



Regards,
Tom Barr

 

[tnnlynch]

Re: False No3 reading

I know the low regard test kits are held in around here and I can understand that. I use them to give me a general idea where the levels are usually every two weeks or so. If it wasn't for the algae issues I continue to fight I probably would have dropped that to once a month or less. I'll give Amquel a try next bottle.

 

[Tom Barr]

Re: False No3 reading

Greg Morin has attempted to get me off my old habits of using Amquel. But I've stuck with the Amquel too long I suppose.

I got to straight chemicals from there, eg Sodium thiosulfate etc.

Regards,
Tom Barr

 

[tnnlynch]

Re: False No3 reading

I'll stick with the simple premixed stuff.

For what it is worth, my retest did not have the same results. I'm very confused as my continued low Nitrate readings. 0-5 ppm NO3 when I'm adding 2 tsp of KNO3 every other day and avery high PO4 reading (5+) when I am adding nothing.

I do have a bio core in my filter (for no reason I just didn't remove it). I wonder if that could be competing against for the NO3?

Tom

 

[Laith]

Re: False No3 reading

Why don't you test your test kit on a solution with a known concentration of NO3?

The other day I added 4.1g of KNO3 in 500ml of RO water. 1ml of this solution in 1000ml of RO water should give me 5.03mg/l of NO3. I added 4ml to have a concentration of 20mg/l of NO3 and then used two test kits against it.

Surprisingly, the LaMotte test kit showed 30mg/l while my cheaper JBL test kit was right on 20mg/l!

 

[Tom Barr]

Re: False No3 reading

Laith, it does depend on the range the test kit is effective over.
Most colormetric test have both low, mid and high range test kits.
pH, PO4, NO4 all do.

In the upper ranges, they tend to get squirrlely.

Regards,
Tom Barr

 

[tnnlynch]

Re: False No3 reading

My ro test solution tested perfectly. I just seem unable to maintain any testable concentration of NO3 in my tank past the day I add it. I'm not sure what I'm doing wrong but I must be missing something.
Tom

 

[Tom Barr]

Re: False No3 reading

Here's the other thing you can do to test it and this will be easy.

Add enough NO3 to make a 10ppm sample.
Measure it. If it concurs, then take the next step, add some prime at the recommeneded amoutns for the volume of water(try a 1 gal or 5 gal bucket full etc.

Measure that after 5 minutes.
Still the same?

That is one simple test you can do to see if the NO3 is influenced by the Prime.

It'll answer your question.

If it is the same, then you can rule out the Prime as a cause and start to focus on some other issue.

Try adding 20ppm this time and see what the decay curve looks like over time.

Regards,
Tom Barr