False high Nitrates after 30 days of cycle?

[LukeyB]

I've been cycling my tank for 30 days now, and I started it off using Dr Tims Bottle Bac and 1 dose of Ammonia Chloride. For the first 21 days I was registering total Ammonia in the 2-4ppm range and my Nitrates were pretty low at about 5-10ppm. As per another thread on this forum, I was advised that the free amonnia was most likely at safe levels and it should be OK to add a couple of fish, which I did last week. The fish have survived and appear healthly, so that's good and obviously it was correct advice.

In the last few days, my total ammonia readings have reduced to almost zero (yay!) but my Nitrate readings have jumped up to about 50ppm. To me that seems very high, given I've only ever dosed the ammonia chloride once, and there are no other sources of nitrate that I can think of. I've only just started feeding the fish a couple of days ago, and only one very small half pinch of pellet per day.

So my question is, do you think it's some Nitrites that are causing a false high positive on my Nitrate test? If yes, I suppose i could verify it by getting a nitrite test kit? However, in that case I shouldn't worry and just let the cycle continue and it'll eventually the Nitrites will reduce to zero and my Nitrate test will then show a correct/lower figure. Otherwise, if is a genuine 50ppm of Nitrate, then I guess I'll need to start doing some pretty big (50%+) water changes to dilute it down, before I run into algae or fish health problems etc.

 

[Garf]

I've been cycling my tank for 30 days now, and I started it off using Dr Tims Bottle Bac and 1 dose of Ammonia Chloride. For the first 21 days I was registering total Ammonia in the 2-4ppm range and my Nitrates were pretty low at about 5-10ppm. As per another thread on this forum, I was advised that the free amonnia was most likely at safe levels and it should be OK to add a couple of fish, which I did last week. The fish have survived and appear healthly, so that's good and obviously it was correct advice.

In the last few days, my total ammonia readings have reduced to almost zero (yay!) but my Nitrate readings have jumped up to about 50ppm. To me that seems very high, given I've only ever dosed the ammonia chloride once, and there are no other sources of nitrate that I can think of. I've only just started feeding the fish a couple of days ago, and only one very small half pinch of pellet per day.

So my question is, do you think it's some Nitrites that are causing a false high positive on my Nitrate test? If yes, I suppose i could verify it by getting a nitrite test kit? However, in that case I shouldn't worry and just let the cycle continue and it'll eventually the Nitrites will reduce to zero and my Nitrate test will then show a correct/lower figure. Otherwise, if is a genuine 50ppm of Nitrate, then I guess I'll need to start doing some pretty big (50%+) water changes to dilute it down, before I run into algae or fish health problems etc.

Sounds right except the bit about the algae, you’ll get that anyhow, if things are good
I’d stick to your whaterchange plan, whatever that is.

 

[exnisstech]

I would verify with a second test kit. If still high I would do water changes. FWIW I don't even own a nitrite or ammonia test kit. When I see nitrates I call it cycled and slowly proceed.

 

[paragrouper]

Assuming your test is accurate, your nitrates would represent elevated nutrients (fish food, fish poop, etc..)

how big is your tank?
how many fish did you add?
how often do you feed them?
what are you using for nutrient export (Refugium, prtotein skimmer, Etc..)?

 

[LukeyB]

Fish were only added 5 days ago. Just two clownfish in 250L aquarium. Hardly feed them, maybe 3x half pinches since adding them. I really don't think the sudden spike to 50ppm nitrate can be caused my thay tiny amount of food? I'm running skimmer and also Chaeto in refugium.

 

[LukeyB]

Reason for my question is that I did read this... 1 ppm ammonia --> 2.7 ppm nitrite --> 3.6 ppm nitrate.

Therefore, given the highest reading I had for ammonia was 4ppm when I initially dosed it, then my nitrates after the cycle should be about 15ppm.

Feels to me like I've still got nitrites which are magnifying the nitrate reading somewhat. I don't want to have to start doing massive water changes unless I really have to. I will Pickup nitrite test kit later today to confirm if my assumption is correct, before I go down the route of doing big water changes which is a pain in the butt!

 

[Garf]

Reason for my question is that I did read this... 1 ppm ammonia --> 2.7 ppm nitrite --> 3.6 ppm nitrate.

Therefore, given the highest reading I had for ammonia was 4ppm when I initially dosed it, then my nitrates after the cycle should be about 15ppm.

Feels to me like I've still got nitrites which are magnifying the nitrate reading somewhat. I don't want to have to start doing massive water changes unless I really have to. I will Pickup nitrite test kit later today to confirm if my assumption is correct, before I go down the route of doing big water changes which is a pain in the butt!

You’re gonna be good at this reefing thing, I can tell

 

[LukeyB]

OK I think I've answered my own question!

I got a Nitrite test kit today and I'm getting a result somewhere inbetween 0.5 and 1.0 ppm (hard to tell exactly but it's in that range).

Given the way the salifert Nitrate tests work, when I test for Nitrates the Nitrite in the water is multiplying through by a factor something like 50 or 100 times (I'm not 100% sure on the ratio but it's something like that). Therefore, my earlier Nitrate test result showing 50ppm Nitrate is actually a false result, and is almost entirely being driven by the 0.5-1.0ppm of Nitrites that I've currently got, with very low actual Nitrates.

I'm going to just wait for the Nitrites to cycle through over the next couple of weeks, and not worry too much about the Nitrate reading until the Nitrites have gone. I don't see an urgent reason to do any large water changes at this stage, as 1ppm of Nitrites isn't toxic in a marine aquarium and I most likely don't have any nitrates at all, or very low anyway.

 

[Randy Holmes-Farley]

OK I think I've answered my own question!

I got a Nitrite test kit today and I'm getting a result somewhere inbetween 0.5 and 1.0 ppm (hard to tell exactly but it's in that range).

Given the way the salifert Nitrate tests work, when I test for Nitrates the Nitrite in the water is multiplying through by a factor something like 50 or 100 times (I'm not 100% sure on the ratio but it's something like that). Therefore, my earlier Nitrate test result showing 50ppm Nitrate is actually a false result, and is almost entirely being driven by the 0.5-1.0ppm of Nitrites that I've currently got, with very low actual Nitrates.

I'm going to just wait for the Nitrites to cycle through over the next couple of weeks, and not worry too much about the Nitrate reading until the Nitrites have gone. I don't see an urgent reason to do any large water changes at this stage, as 1ppm of Nitrites isn't toxic in a marine aquarium and I most likely don't have any nitrates at all, or very low anyway.

That all sounds reasonable to me.