Strange test results

[Analog Saint]

My tank was averaging about 2.5 PPM ammonia per day- figured this friday I'd be up to my target of about 3 PPM and could stock my tank (it's going to be very understocked)... I put in about 4-5 PPM in the form of about two generous tablespoons of ammonia yesterday at about 5 p.m. and expected it to read somewhere within the 2-3 PPM ammonia and 0 nitrites the next day...

Today, I took my readings a bit earlier than 5... WOW- Reading a perfect 0 on the Ammonia scale. Never had that happen before- there was always a miniscule amount left over. Now, it's perfectly yellow without the slightest hint of green.

Thought that was strange, so I repeated the tests, and decided to look for Nitrites. I haven't seen any in almost two weeks despite constant drops in ammonia... It's all been going straight to Nitrates. Surprise! Another 0 Ammonia, and the nitrates are back, at about 3 PPM.

If I put in 5 ppm of Ammonia, and it was all eaten up, that would make a substantial amount of nitrites, much greater than what the colonies of bacteria have previously been feeding upon- and thus the 3 PPM excess. What confuses me is how the bacteria went from a little more than 2 PPM of ammonia to nitrates per day to removing 5 PPM ammonia overnight.

Tank is buffered, pH at about 8 due to baking soda. Heat at 84 degrees. Lights have been off for three weeks to prevent any algae blooms. After I got the double check on the 0 reading in Ammonia, I added another 2 tbsp to take it back up to about 4-5 PPM. I'm going to take a reading in an hour, and then do another before I go to bed tonight and see how much it processed in 12 hours. If it really is eating up 5 ppm, I'd like to thank whoever spiked my tank with Bio-Spira while I was sleeping- or I must offer sacrifice to the cycling Gods or something...

Questions:
1) Which is more likely, that the Ammonia-reducing bacteria simply outmultiplied the Nitrite-reducing bacteria, or a high ammonia concentration (by high I mean 5 PPM) somehow damaged the Nitrite-reducing colonies?
2) Anyone have any advice besides putting off stocking until this is solved? Much appreciated.

 

[happychem]

Well, first of all, put off stocking until you can clearly see that your addition of NH3 goes straight to NO3 with no measurable NO2 the next morning.

My guess at what happened is that the NH3 oxidizers boosted their colony size. NH3 is much more favourable energetically than NO2 (as a rule for the amount of energy an organism can get out of food, look at the number of H's vs. O's, less H means less energy, but just for comparison purposes). Anyway, my point is that it means that NH3 oxidizers can multiply much faster than NO2 oxidizers.

Also, NH3 oxidizers aren't reliant on another organism for food, NO2 oxidizers can only process what NH3 oxidizers give them.

So what I think happened is that you had a steady state between colony sizes: NH3 nitrifiers were populous enough to consume most, but not all of the NH3 you added, then the NO2 nitrifiers grew up to convert that to NO3. Recently you've seen NH3 nitrifier population explode, there's now a surplus of NO2, in time the NO2 nitrifier colony will grow to consume it.

I suggest a great big water change, it won't hurt the colonies, but it will give you a good clean slate to analyse what's happening with. Replace most of your water and dose your 2 tbsp. NH3. Measure all three species after a half hour, for mixing, to be certain (I know, you pretty much are, but I'm neurotic when it comes to these things), besides it's good to have a baseline.

12 hours later, test for all three again. This should either confirm my hypothesis or, from the state that your cycle appears to be in, indicate a completed cycle. Then you can do a final water change and get your fish, just remember to continue dosing NH3 until you're ready to stock! And stock to your full final level, or really, really close, because more likely than not, your full stocking level will not be producing the level of NH3 that you were initially providing, so a portion of your colonies will die off.

 

[Analog Saint]

The other thing I thought of was my Bio-wheel... The wheel wasn't turning as quickly as it normally did, because the media was off center on the wheel, and so occasionally it would stick out and slow the rotation of the wheel. I just caught onto it about two days ago. I realigned the media on the wheel so that it doesn't interfere with rotation, and now it's spinning as fast as when I first got it. Since I normally only put in 2 tbsp every two days, I think the addition of 4tbsp in two days may have given the ammonia-nitrifiers a chance to out-multiply the nitrate-nitrifiers, and they're now going to have to grow to take care of the extra nitrite output.

I'll do a large water change, take baselines, and see where in the cycle I am... If it is a second nitrite spike, I'll give it a bit more time. I'll stock the week after next- because I'll have a genetics and orgo chem exam to study for this weekend.

Thanks for the advice!

 

[happychem]

Ah org. the reason I got into chemistry! And then subsequently drifted through the sub-disciplines...

 

[Analog Saint]

WHOA! I didn't get a chance to do that water change due to an Experimental Design quiz... I checked my parameters before I did it today....

Yesterday at 1 pm: 5ppm Ammonia... 4 ppm Nitrate... pH 8.0
Today at 1 pm : 0ppm Ammonia... 0 ppm Nitrate... pH 7.8... GH: 5 degrees hardness.

I doublechecked my results to make sure I wasn't dreaming... My tank really has gone from cycling 3ppm ammonia and nitrate to 5 ppm ammonia and nitrate in three days. Gonna keep up my doses of ammonia and the occasional spoonful of sodium bicarbonate, and after my midterms- I'm finally gonna get my Kribs...

And Orgo rocks my socks. I was rather indifferent about General Chem I and II, but Orgo is much more challenging and enjoyable at the same time. If I wasn't so geared to Psychology, I'd probably be a Biochem or Chem Engineer...