# Nitrates Not Rising



## jonathantc08 (Nov 16, 2012)

Hi guys.

90 gallon tank stocked with 34 Fish all 1.25" to 2" in size. The tank has been setup for about 8 weeks and the fish have been in for 2. I have been testing water for the past week, my nitrates were 40ppm before adding the fish and I did a water change and brought nitrAte down to 20ppm. I added the fish and I have been feeding them very heavy 2 times a day. My ammonia and nitrite have constantly been zero and my nitrAtes are not moving what-so-ever.

I want to mention, I have also done a series of dilutions with distilled water just to see if maybe ammonia and nitrite were soo high that it was giving me a false 0 reading. I did 1/2 and 1/4 dilutions and tests were all negative for either ammonia or nitrite.

The only thing I can think of is I'm understocked and not producing much ammonia but other than that I really have no logical explaination.... I highly doubt that I'm understocked

I don't have much experience so maybe you can shed some light on this situation for me.
Thanks very much


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## BC in SK (Aug 11, 2012)

A few possibilities:
1. Test kit not accurate
2. algae has taken up the nitrate produced over the last 2 weeks
3. this nitrogen is now part of the bacterial population.


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## kmuda (Nov 27, 2009)

Why distilled water? Have you reconstituted it with any of the products on the market such as SeaChem Replinish or Kent R/O Right? Or is your tap water so hard that diluting with distilled water just brings it down to normal ranges.

Distilled water is inherently unhealthy for fish as it is completely void of minerals and trace elements. Being absent a KH buffer, it cannot maintain a stable pH and the pH will quickly decline into very low (sub 6) areas. With a pH this low, ammonia oxidizing bacteria basically go dormant and cease converting ammonia into nitrite (and subsequently nitrite into nitrate). But at a pH this low, ammonia will be in it's non-toxic form ammonium. Some test kits only register ammonia and will not pick up the ammonium.

What is the pH of your tank? Do you know the KH and GH readings?


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## jonathantc08 (Nov 16, 2012)

BC in SK said:


> A few possibilities:
> 3. this nitrogen is now part of the bacterial population.


I didn't think of that... so what does that mean if this is the case? those bacteria have to be removed or else I'll have a huge nitrate spike when they die off right?



kmuda said:


> Why distilled water?


kmuda... I saw a video by Dr. Tim showing that sometimes ammonia or nitrite concentrations can be so high they are off the charts, but the test kits available for hobbyists will read that there is zero. So in order to bring down the concentration into a range that the liquid test kit could register you have to dilute it will distilled water... The distilled water wasn't put into my tank. I don't use any chemicals. I was simply diluting the test water I pulled out of the tank. my pH is fine at 8.2 and I haven't checked my GH and KH lately but I'm pretty confident that its the same since I have aragonite and crushed coral in my sand substrate.


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## kmuda (Nov 27, 2009)

I misunderstood. Thanks for the clarification.

Something is not right. Either your nitrate test kit has expired, the test is not being properly conducted (all of the shaking required for both the #2 bottle and the test tube after the 10 drops of #2 bottle are added), or there is something in your water that interferes with the test. I know that brand new liquid regent test kits that where bottle two is not well shaken will result zero readings. Some water conditioners (Amquel Plus comes to mind) have been know to interfere with some nitrate test kits.

It is highly unlikely to impossible that denitrification is occurring to an extent that you would be reading zero nitrates. For the nitrates to be "part of the bacterial population" you would have to have the necessary carbon sources for this to occur..... and you are not accidentally going to walk into these carbon sources, unless you have filter media manufactured from polycaprolactone (PCL) (unlikely, Tetra holds the patent and has not done anything with it other than Instant Ocean Nitrate Reducer, which does not work in our tanks), poly hydroxyalkanoates (PHA - or Dr. Tim's NP Active Pearls) or are carbon dosing with Vodka. Regardless, in any case, you would have found a brown slime coating your filter media and substrate if using any of these products without the appropriate precautions.... and in the case of vodka dosing, there are no precautions, you will be slimed with no results (as reflected by denitrification) unless you are running monster mechanical filtration to the tune of 100 microns or better and are frequently replacing that media.

All stated only to urge you to look for a more realistic cause of the absence of nitrates. Do you have another tank where you can confirm your test kit is properly functional? Are you using test strips or a liquid regent test kit?


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## kmuda (Nov 27, 2009)

kmuda said:


> It is highly unlikely to impossible that denitrification is occurring to an extent that you would be reading zero nitrates.


Clarification.... or not seeing any nitrate creep.


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## BC in SK (Aug 11, 2012)

jonathantc08 said:


> BC in SK said:
> 
> 
> > A few possibilities:
> ...


 I'm speculating on a possibility.....your feeding twice a day; that nitrogen is still in the system some where as it could not have simply vanished. Growth of young fish could very well acount for the majority of the food. But fish do produce waste, and ammonia as a by product of respiration. I have no idea on how much bacteria could be in an aquarium. In soil, very significant amounts of nitrogen can be tied up by bacteria......but there is definately a lot less bacteria in an aquarium, then their is in soil. I would supose a population reaches an equilibrium.... then after that you're seldom gaining or losing any nitrogen. If you did a fishless cycle, now that you are feeding your fish,maybe a previously limiting nutrient caused a sudden rise in the bacterial population (?).

By the way, I placed the 3 possibilities that i posted, in descending order of likelyhood, IMO. I still think an inaccurate or faulty test, is most likely. The distinction between 20-30 ppm may not be that readable (?).


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## jonathantc08 (Nov 16, 2012)

kmuda said:


> Do you have another tank where you can confirm your test kit is properly functional? Are you using test strips or a liquid regent test kit?


Yeah I've already ruled out the possibility my test kit is the cause. I have a 45 gallon and I saw the nitrates steadily rise like it normally does in a week. I am using API master test kit which is a salicylic acid test kit, and my dechlorinator is Aqua Cleanse by Dr. Tim's (I've confirmed it does not interfere with salicylic acid test kits.) I don't have any crazy mechanical filtration or anything that I think could be removing the nitrates. since 20ppm and 30ppm are so hard to distinguish on the API tests I could very well have a small nitrate creep that I haven't been able to see.



> I'm speculating on a possibility.....your feeding twice a day; that nitrogen is still in the system some where as it could not have simply vanished. Growth of young fish could very well account for the majority of the food. I would suppose a population reaches an equilibrium....


I have actually seen a substantial amount of growth in the last 2 weeks. I'm going to give it a couple more days and I'll let you guys know where my nitrates are... I think I should be able to discern between 20-30ppm by then if not then it's a mystery!


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