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-   -   Standalone nitrogen cycle AKA Cycling a plantless, substrateless, filterless tank (

JDM 05-23-2013 10:25 AM

Standalone nitrogen cycle AKA Cycling a plantless, substrateless, filterless tank
OK, so it's a bottle.

I keep seeing all the talk about surface area and biofilms (more often called bacterial colonies here) and how they need to be maximized in order to be able to handle the ammonia created by the fish that we keep. A while back I did some calculations to compare the surface area of sand and gravel substrates of various grain sizes and various filter media and determined that the filter, as far as biological filtration is concerned, was a small part of the equation.This is sort of an experiment to see if even all that area is really needed in the first place.

Being a planted tank person I believe that plants are the easiest and best option but understand that not everyone wants to deal with plants for a variety of reasons. As a result, I skipped the whole tank cycling process. I understand that it still happens in the background even with a ton of plants and that it effectively becomes a dual system. I have since decided that I want to try creating a stand alone nitrogen cycle and do it in the simplest controlled environment possible, mainly to see what it is all about. I'm even using fish food that I would have otherwise thrown out... so it is a very cheap experiment.

Interestingly, there are more surface square inches of glass per gallon of water in my bottle than in my rectangular tank by a factor of 5 so I consider that compensates for the lack of filter and substrate to a certain degree.

I am using tap water at room temperature, fish food as an ammonia source with no substrate, plants, filter or circulation other than me moving it every once in awhile. I am aiming to keep the ammonia no higher than 1ppm. Water testing will be once per 24 hour period for ammonia and nitrites and nitrates only periodically. I am not concerned with nitrates and I really donít want to have to do all that shaking anyway. The prime indicators of cycle completion are really the ammonia and nitrites dropping to zero with new ammonia added.

Tuesday I set up the jar, filled it with water and added four medium sized sinking pellets... probably too much for a small volume, but I can adjust as needed. Yesterday I tested ammonia at 0.25ppm. Right on cue. Nitrites were zero or at least unmeasurable with the test kit.


JDM 05-25-2013 02:31 PM

Day 4

Tested ammonia, 1.0 ppm. I have not added any more food yet, obviously no need. I did a 2/3 water change to bring the concentration down to .3 ppm estimated as I want to keep it below the 1.0 ppm threshold. Easiest water change ever, pour out what I want to change and run the tap to fill it, all water changes should be so easy.

Nitrites are at 0.125 ppm if I have to put a number on it. The colour is sort of halfway between 0 and 0.25ppm. The water change reduced these as well, which is fine.

I still haven't tested for nitrates. The issue is that nitrates are produced 1 for 1 from ammonia. At least that is what I am lead to understand so the nitrate colour scale is 0, 5, 10, 20 etc, it is not nearly so sensitive as the ammonia and nitrite tests. Once I see them appear as non zero I can probably test every 5 days and get a better idea of their buildup.

The water appears a little murky but not terribly cloudy or anything. If it were a much larger volume perhaps the murky would be more apparent as there would be more of it to try to look through.


fish keeper 2013 05-25-2013 02:54 PM

Sounds interesting, you said you are using tap water, won't that inhibit the cycle? Chloramines doesn't evaporate...

Oh yeah, how big is the bottle?

It sounds like a cool experiment, keep us updated!

JDM 05-25-2013 03:09 PM

I'm on a well. Even so, I doubt that even the chloramine would inhibit the cycle being established by much. Even so, if I were doing this with city water I would still treat with prime anyway.

Bottle is about 1/3 of a gallon.

I hear that small water volumes are harder to get a cycle going, I doubt that now that I have done the math. It may be harder to keep it balanced with fish, I expect, as it takes far less ammonia to spike the concentration than in a larger volume but I have no plan to put fish in this.


Mikaila31 05-25-2013 05:00 PM

I would be more interested in seeing how it worked using regular ammonium hydroxide. I expect it to work either way but decomposing fish food relies on a lot more bacteria then just then just ammonia to nitrate conversion. So I guess the question is what exactly are you trying to figure out? Nitrosomas and nitrospira/nitrobacter bacteria convert ammonia to nitrate and that its all. Breaking down fish food is going to rely on many other bacteria to produce the ammonia. I would wonder about oxygen levels when you have little more then surface diffusion going on and are trying for high bacterial activity. Low oxygen is going to slow the bacteria down.

I'm not sure why you are focused on surface area? Nitrogen fixing bacteria can colonize as heavily or sparsely as needed usually. I've personally never worried about surface area apart from the surface area of the water. Where aerobic nitrogen fixers colonize depends on a lot more then just surface area. I am one of those that believes the filter is often a large source of the nitrogen fixing bacteria in the tank, but that does depend on how both the tank and filter are setup. They certainly don't need the filter to colonize an aquarium, but the conditions in the filter are usually more ideal.

JDM 05-25-2013 05:54 PM

Seeing as I had ammonia within 24 hours of putting the fish food in the water, the initial bacterial activity is next to negligible in the whole picture, so the difference between using a pure ammonia source and fish food is one of neatness and maybe accuracy for the sole sake of accuracy. I can add food to bring the levels up or not change the water so soon but the 1ppm ammonia has been proven to be a threshold over which the nitrite oxidizers are inhibited from doing what they do best. I would have liked to do a side by side to prove this extends the cycle timeline but researchers have already done this.

Knowing how much food I added to bring the ammonia to 1ppm in an uncycled container lets me know how to judge the cycled container in testing afterwards to see how effective the biofilms are in this nitrogen cycle.

The surface area is not really of interest, just the fact that there is no additional surface area involved other than the glass container itself. I read about biological filter media and hold the opinion that they are not nearly as effective as advertised in many cases (although they don't really make claims that they are, just intimate that they are by their nature) and are not really needed in the first place. So rather than prove them not effective, it's easier to prove them unnecessary and therefore a waste of time and money... even if only to me.

I expect that not many will like my attitude toward well known and trusted brand name manufacturers' biological media products but that is my nature, to look under the marketing.

Also, I asked a couple of months ago for some timelines from people and their cycle setups and didn't receive any feedback. I just needed to establish what a timeline would be for my own curiosity, and I would have done it for that reason alone... it's just more fun to have other reasons as well.


Mikaila31 05-25-2013 07:58 PM

well I certainly agree biological media is a waste. Its not something I would bother picking to use in my filters. The only bio media I have is stuff that came with filters or I that bought 6 years ago. I do view them more as a marketing gimmick. I have some ceramic noodles(rena or fluval brand) that have been in constant use for 6 years. Yet when you hit one of them with a hammer the inside is still nice and dry and as white as when I bought them. I have never seen anyone prove they function any better then standard sponges/floss. I've always preferred good sponges and floss over any other media. I keep wanting to buy a bunch of poret foam but keep talking myself out of it =/

JDM 05-25-2013 08:09 PM

I just did the ceramic noodle test a week or two ago and found the same thing... although I intentionally broke it expecting that result.

Poret foam, interesting cell structure. It just looks like custom cut foam unless you look closer but is it that much better? It reminds me of the filter foam used in small engine carburation.


Mikaila31 05-25-2013 10:15 PM

Poret foam is said to be better but I expect that could be questionable, since it is simply foam. Its actually not that easy to find customizable open cell foam for the aquarium. A number of filters use/sell just one pore size when it comes to sponges/foam, it may work for some, but filters run a whole lot better with various sizes. Any filter running 10,20,30ppi foam, and floss is going to filter and polish water very well both biologically and mechanically. Poret foam is more rigid then any other foam I have come across, that is the most noticeable difference to me anyway. When ever someone wants a hamburger mattenfilter it is the go to foam for that. But far as I know both the foam and that filter design came from Germany so its not that surprising. I mainly want it just so I know pore size and it is sold in easy customizable blocks or sheets. Its not like foam goes bad or needs replacing regularly. Its pretty affordable if you have lots of tanks, I just don't.... yet. I do have a couple of unused canister filters I got really cheap that need media and I would rather not buy the over priced pads sold for them. I have a habit of collecting equipment:roll:. The US seller of poret foam moved close to me recently. Which means I will probably end up buying some if they start coming to some of the local club events around here, one way to get out of shipping costs lol.

JDM 05-29-2013 10:12 AM

Day 7

Interesting test results yesterday. Ammonia at 1ppm, it seems to be peaking at 1 each day. Nitrites have dropped to zero but I haven't tested yet today to see if they are steady zero. I was going to test nitrates every five days but maybe I'll add one in today to see if there are any yet.

It's too early to tell if this is the telltale nitrite drop. I should dump the water altogether and add fresh food, I haven't had to add any yet as the ammonia levels have remained high... in fact I could have done with less food to start with an brought it up gradually to eliminate some of the water changes... not that they are hard.

I might start another bottle to produce ammonia laden water to add to the first jar so I can better fast the ammonia is dealt with. Easier to see a static 1ppm concentration and time the disappearance than try to judge based on constantly decaying food. I would sooner do this than go buy ammonia for no other reason than I don't have time to go looking for a pure source but the pure source may have been more revealing of what is going on.


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