Freshwater cycling

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authmal

Pseudonovice
Aug 4, 2011
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I think we're all confused as to why you wouldn't want dechlorinated water. Bottled water is much more resource intensive: it's more expensive, needs buffering, need to get it into the house and then the tank.

Maybe a more cogent explanation of what you're looking to achieve, and what questions you actually have? As it is, your original post is asking for help, but it *seems* like you're trying to cycle your tank (and simply need more time), and we're not sure where the misunderstanding is.
 

GenteelBen

AC Members
Mar 14, 2020
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Hey, guys. I'm cycling my first tank using the instructions that T TwoTankAmin has posted around the forums. It's a seven gallon planted tank. I added a little too much ammonia with my first dose. I expected to see a measurable level of nitrite on day four of the cycle, but the test kit reads zero. I am getting a reading for nitrate. So, my interpretation is that the nitrite level is probably higher than the test kit can read, but should decline rapidly in the coming days. Thus, I test again in three days. Agree or disagree? Here is my data:

DATEAMMONIANITRITENITRATE
Day 1 (3/28/20)4N/AN/A
Day 4 (4/1/20)1.505
 

CichlidFins

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Feb 26, 2020
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Jay
Hi there, if you are reading nitrates it means that your nitrite bacteria have already grown and are eating the nitrite as it comes along. You may or may not see nitrite in your cycle, but as long as you have nitrates you will know that the bacteria are doing their job :)
 
Apr 2, 2002
2,348
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New York
Sorry, this will be a long post.

If your nitrite were too high, it should read at the top of the scale. Do you have plants in this tank?

It is possible to calculate the amount of nitrite and nitrate a given level of ammonia should produce when using an total ion kit like API uses. If one were using the nitrogen scale, the only thing that matters in NH3/NH4, N)2 and NO3 is the N aka nitrogen. So, if ome has a test that uses the Nitrogen scale, 1 ppm of ammonia = 1 ppm nitrite = 1 ppm nitrate. This is because all that is being measured is the N. But when using the total ion scale one is not only measuring the N they are also measuring the 3 or 4H in the ammonia, the 2 O int the nitrite and the 3 O in the nitrate. If we look at the atomic weights of all these things here is what we have with which to work.

The atomic weight of N is 14.0067, O is 15.9994 and H is 1.00794. And with this info we can calculate the atomic weight for each ion:

Ammonia as NH3 = 14.0064 + 1.00794 x 3 = 3.02370 which results in an atomic weight of 17.03010
Ammonia as NH4 = 14.0064 + 1.00794 x 4 = 4.03176 which results in an atomic weight of 18.03816
But the API kits measure Total ammonia which is NH3 + NH4. Depending on the pH and temp of the water, one could calculate the exact values in a tank. However, for this discussion we can consider TA would average an atomic weight of about17.80 since it is mostly NH4.

Nitrite as NO2 = 14.0064 + 15.9994 x 2 = 31.99880 which results in an atomic weight of 46.0052.
Nitrate as NO3 = 14.0064 + 15.9994 x 3 = 47.99820 which results in an atomic weight of 62.0046.

From all the above we can now say that 1 ppm of TA on the ion scale has an atomic weight of 17.8. If that is converted completely to nitrite the result would be an atomic weight of 46.0052. And from this we can calculate that 17.8 becomes 46.0052 and that means there is 2.58 time as much nitrite as TA (46.0052 divided by17.8). 1 ppm of total ammonia would turn into a maximum of 2.58 ppm of nitrite. Continuing in this vein, 1 ppm ot TA if it is completely converted to nitrite which in turn is completely converted to nitrate would mean that 17.8 becomes 62.0046 and that means there is 3.48 times as much nitrate as T (62.0046/17.8). Moreover we can see that 46.0052 of nitrite becomes 62.0046 of nitrate, or 1.35 times as much nitrate as nitrite (62.0046/46.0052).

These numbers are a guide to the relative values for TA, NO2 and NO3 that are the maximum that can be in in the water. However, things can mitigate the numbers. Ammonia can evaporate or be consumed by plants or algae. Some amount of nitrite and nitrate can become an acid. So the process is not as exact as the numbers indicate, However, we can use them to ballpark what is going on.

In this case the 4 ppm of TA in the tank on day one was 1.5 ppm on day 4. that means 2.5 ppm of ammonia was converted to something else. If it were all turned to nitrite theRE would have been 2.5 x 2.58 = 6.45 ppm of nitrite. This should have PRODUCED a reading for nitrite , not 0. Further, that nitrite would have become a maximum of 8.71 ppm of nitrate. Bearing in mind there is not a 100% throughput, the actual nitrite and nitrate levels would be a bit lower than the absolute math indicates. Evemn so there sould be a nitrite reading for sure.

Since we know that that the ammonia bacteria multiplies faster than the ones for nitrite conversion, and since the nitrite bacteria do not start to reproduce until there is nitrite present. There most certainly shoul be a nitrite reading on day 4. So i am thinking there must be testing error or an expired kit. The nitrate kit is the least accurate of the three and it is most inaccurate between 0 and 20 ppm. The problem there is that the nitrate kit works by turning the nitrate into nitrite and then measuring that. During a fishless cycle oif there is nitrite present, it will get counted as nitrate on the test for that.

It seems more likely to me that there is nitrite but not nitrate. The nitrate reading could actually be nitrite. In order to get an idea of what is actually going on, I wonder what the tap water parameters are is in this case. There is a;so a possible issue with the use of dechlor. Most of these today are able to detoxify chloramine as well as chlorine. When the former is broken down, it becomes chlorine and ammonia. If one has dechlor which also detoxifies ammonia, an ammonia test can be inaccurate unless it is done very soon after the dechlor has been added.

More info is needed to figure out what is going on. Test your tap parameters, Be sure to leave the water out overnight or else bubble it in a glass with an air stone for 15 minutes before testing for pH. Test for ammonia, pH and nitrate in the tap. If you have the kit, test for KH. In addition to the test restuls, tell us what decor and substrate are in the tank as well as about any live plants or obvious algae. Also,what dechlor do you use and do you add anything else to the water?
 

GenteelBen

AC Members
Mar 14, 2020
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Thanks for the post T TwoTankAmin . There is a lot of good information in there -- and I did my best to follow it. My takeaways are that there is a multiplier in the stages from ammonia to nitrate (where 1 ppm ammonia creates a higher ppm level of nitrite, which creates a higher ppm level of nitrate). And, if we had a tank with no substrate, no evaporation, no plants etc., then we should be able to calculate exactly how much nitrite and nitrate a given level of ammonia would produce. But, we have tank parameters and other things that use ammonia or affect the conversion. Still we should still be able to make a general prediction about the levels.

So, I measured my tap parameters and took new readings on the tank. The test kit is not expired. I must have made an error when I performed the last test on the tank water. Here are the different water parameters followed by some information about my tank:

TAP LEVELSPHGHKHAMMONIANITRATE
April 20207.6107.450.250


DATEAMMONIANITRITENITRATE
Day 1 (3/28/20)4N/AN/A
Day 4 (4/1/20)1.50 (testing error?)5 (testing error?)
Day 7 (4/4/20)1110

Substrate: Seachem fluorite with a sand cap
Tank decor: Petrified wood and bubbler decoration
Plants: 2 bacopa caroliniana, 2 cryptocoryne parva, and redroot floater
Water conditioner: Fritz Complete Full-Spectrum Water Conditioner
Other water additions: Easy Green Fertilizer
Tank water is 78 degrees

The bacopa has been melting but the cryptocorne is holding strong. The tank was planted and running for 4 or 5 days before the first dose of ammonia because I did not have ammonia at that time.

My interpretation of the most recent levels is that I expect to test again in 3 days. I may be getting close to dose 2 as ammonia is falling and I have a nitrite reading.
 
Apr 2, 2002
2,348
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New York
@CenteelBen
Yes, you got it perfectly. When a scientists tests our tanks he will use a test based on the nitrogen scale and he/she will tell use that one ppm of ammonia creates one ppm of nitrite and of nitrate. That is because the chemical formula for all three of these things contains one N. But most of our hobby kits measure the rest of the things present which in turne causes the numbers to increase at each level. Think of it like measuring temperature in C v.s. F. Water boils at the same point at sea level whether we call it 212F or 100C. There are conversion factors for the nitrogen complex measurement scales just as there are for converting C-> F/F->C. Here is one https://www.hamzasreef.com/Contents/Calculators/NitrogenIonConversion.php

Your added info helps to clarify what is going on on the tank. Plants change the equation. One cannot use the rulwes.mthods for doing a fishless cycle with no plants for doing the cycle with some amount of plants present. Further, just as different fish species have different tolerance levels for ammonia, nitrite and nitrate, the same is true for plants. Most plants take up NH4 while the bacteria want NH3. Because there are both forms of ammonia in a tank and that the balance is determined by the pH and temperature of the water in the tank, it is impossible to come up with rules or values for nitrogen is such cases. But too much NH3 can harm both plans and fish.

If one is doing a plain vanilla cycle with no plants, the amount of time it might take is not written in stone. Even when the same amount of ammonia is being dosed. we still cannot tell at the outset how many days it will take for any given tank to become cycled. The reason for this is really very simple when we think about it. The answer depends on how much bacteria is present in the tank when we start a cycle. There is absolutely no way to know the answer. However, we can understand why there can be such differences if we consider a simple example of two identical tanks with one difference, tank A has 10 individual bacterium for ammonia conversion at the start while tank B has 20. For this example we will assume that the doubling rate in the tanks for ammonia bacteria is 8 hours.

Consider where things will be at the end of 24 hours. Tank A doubles to 20, then 40 and finally 80 after 24 hours. Tank B however doubles to 40m then 80 and finally 160 after 24 hours. So at the end of the first day of cycling where Tank B had started with 20 more bacterium, it now has at four times that being 80 ahead. The only way we can see this might be the case is that Tank A will have more ammonia than tank B at the end of that day. If we assume the tanks need 1,000 individual bacterium to be cycled for handling ammonia, Tank B would have 1,280 at the end of day two while tank A will only have 640. Of course, in reality, the number of individuals is in the millions not the 100s or 1,000s. But this example does illustrate the effect.

This sort of potential difference also applies in the case of plants in a tank. Moreover, while plants do use ammonia, they can also be sensitive to higher levels. It can even harm or kill plants. My normal suggestion relating to cycling with plants is that the formulas go out the window and the amount of ammonia to be added is closer to 1 or 2 ppm than 3 and certainly not 4. So let's assume that one is not adding too much ammonia for plants to handle. What effect will plants have on a fishless cycle?

Since there is no formula we can use here, we will have to rely on the chemistry involved to point us in the proper direction. The first step is to establish ammonia oxidizing bacteria. But with the plants using some amount of the ammonia, we can expect the amount of bacteria needed to be much less and that ammonia levels will drop a lot faster than in a pure fishless cycle with no plants. The changes do not stop with ammonia. because bacteria are converting a lot less of the ammonia, they are also making substantially less nitrite which in turn means less nitrate. Any nitrate that might be created may not last long in planted tanks as plants may use that as well as ammonia.

Given enough live plants, the cycle can be skipped entirely. Gradual stocking will be possible almost as soon as the plants have some time to establish. This is partly due to the fact that the plants arrive with some amount of nitrifying bacteria living on them. The problems hobbyists cannot solve is what lies between no plants and a full load? What is the effect the actual plant load in a specific tank has on cycling? Again, we are faced with the need to come up with a method of answering this question in the absence of any accurate measurements. Creating guidelines and methods for doing this would require a full length article on the topic which I cannot do in a post.
 
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