thoughts on beneficial bacteria, and fishless cycling

[Magnum Man]

so my latest set up tank, a 30 gallon long, appears to be doing fine... this was basically a no cycle tank, by standard definition... the only filter was a twice sized, well used, sponge filter... the catch, is the filter had been dry, out of any tank for 3-4 months... I did have it running for 2-3 weeks, while I waited for various components, with nothing but water in the tank... I do have just a couple tiny anubias nanas in the tank, as well as a few cuttings of pothos vine, that are just now beginning to root... my wild caught, 5 inch yellow acara went right into the tank, once the substrate, and new heater arrived, the substrate is a larger river rock, not the normal aquarium gravel... the fish should be a pretty big bio load for a tank this size... I am using RO water, for the initial fill, and doing about 30% water change twice a week... I've not tested my water, but the fish is looking great...

this makes me question 2 things... did my old dried out sponge filter retain beneficial bacteria in some form, that could come back, after the filter was rewetted???

... and here is the big one... are we just wasting our money and time, by cycling a tank, when, if we are doing as much of a water change as we should be doing, the fish would be fine???

I'm not saying the tank won't cycle, and that a cycled tank is not better for all kinds of reasons, I'm just questioning the need to do fishless cycling, if you are doing proper water changes... thoughts???

 

[MaloK]

The bacteria that form spores could have a longer resistance to drying out, but I would consider it as dead at this point since the bacteria involved in the nitrogen cycle does not produce spores.

There is no proper water changes during initial cycle, whatever you do ammonia and nitrite will always rise until sufficient colonies of bacteria are there to process it, water changes just makes it longer and harder, during this period even 75% water change per day wont prevent the fishes to be exposed all the time.

Completely cycling a tank before use ends in fact with the complete opposite of wasting money.

After I broke my tank and moved everything to a new one, I was forced to do 50% water change per day for 14 days before the nitrogen came back to normal and stopped reaching dangerous level every day. that wasn't economical.

And I wont calculate what if the fishes become sick because of stress from nitrogen exposition could add to the cost of not having a properly cycled tank.

Imagine having to use expensive meds and still be forced to change half the water per day or more to keep a sane environment.

Fishless cycle, is priceless cycle.

 

[AJ356]

In a non cycled tank, if someone starts out with more than one or two fish, unless you had decent plant growth to consume the ammonia before it becomes nitrite... You'd need to literally do 90-100% water change a day to even stand a chance of good parameters. Even 90% or 95% would not be ideal as that 5% and 10% ammonia tainted water would build up. I am talking about if someone put fish in a completely uncycled tank with no plants. A tank with no obvious source of beneficial bacteria to begin with.

I guess someone could use an ammonia blocker of some kind and salt (if the fish can tolerate it) to reduce nitrite toxicity. I think if your pH is under 7, you are more worried about nitrite.

 

[Naughts]

The lack of testing means that the cycle may not be as established as you hope. Is the substrate new? Are the 30% water changes using R/O or tap? If you are using tap, there may be a point when the pH goes above 7 and ammonium converts to harmful ammonia. Also, 2-3 weeks is around the point when you start to get nitrite so the fish could still get sick. Testing would be beneficial.

Regards wasting money, bacterial starters mostly do not contain the correct bacteria, or are not stored properly so yes this can be futile. But if you're just talking about the cost of a bottle of ammonia (assuming you would buy the test kit anyway as a necessary part of water management) - then this is easily offset by the cost of the water. In the UK tap water prices have risen a lot lately, and obviously RO costs more.

 

[TwoTankAmin]

Be patient, your ammonia will rise and your fish may suffer. It takes a little time for the ammonia to build up.

One of the important things the bacteria needs is inorganic carbon. In our tanks that basically comes from 2 sources, CO2 is one and the other is carbonates/bicarbonates. Pure RO contains none of the latter. I suggest you test.

On the other hand because you have no KH, this should allow the pH to drop in the tank and that will turn most of the ammonia created inTO ammonium. This is way less harmful over the short term than ammonia. But of ammonium persists, it will harm fish.

Since you are using RO water, I assume you are not using a dechlor, many of which also contain an ammonia detoxifier. This basically turns the ammonia into ammonium.

Also, water changes slow cycling because you reduce the things that cause the bacteria to multiply the fastest. And then with nitrite, once inside a fish it takes a day or two to work its way out. However, as long as there is any amount of nitrite in the water it will be entering the fish. So water change prolong the time fish will be gasping for air at the surface. Fortunately, chloride in the water at the proper level blocks nitrite from entering the fish. And plain old salt, sodium chloride, in a minimal amount will protect fish.

 

[Magnum Man]

I understand the normal train of thought, but I have a rapidly bubbling sponge filter rated at 65 gallons, in this 30 gallon tank, not sure how long it takes to colonize a twice size filter like that, probably operating at maximum efficiency... the fish is still not showing any signs of problems, it's now been in there 2 weeks, and I'm considering adding an adult silver dollar as a 1st tank mate...

 

[plebian]

Plants are an excellent way to speed up the nitrogen cycle. Since you had the tank running for "2-3 weeks" the nitrogen cycle may have completed. In my experience 2-3 weeks is all it takes if you start with plants.

 

[Magnum Man]

the pothos vines are rooting now, I added them as cuttings originally, but there are several 6-7 inch roots established now....

the adult silver dollar, gets a break from the bichir... there are sill 3 in that tank, that I think by shape, and mobility, the bichir deems them as unedible... these are common silver dollars, but one is more highly colored than the others, and the bichir tank, can't be viewed, except from my work area.... so short of buying a new fish, I think I'll try him in with the yellow acara... worst case, I have to move it back...

 

[TwoTankAmin]

A cycle is driven by the mount of ammonia present, basically. I don't do pothos so I cannot say how much ammonium is wants to use. But, from your description I would assume it may have been doing a lot of the "heavy lifting." A few small anubias will be pretty light weight re ammonia usage. All of my tanks are spread around the house. I need to minimize evaporation so I have pretty decent lids in place on them all. I do no terrestrial plants with their roots in my tanks.

The one benefit to plants handling part of the cycle is that they produce no nitrite and thus no nitrate, which they might use. Test for these, and you can figure out what is going on in the tank. Since your fish is not gasping at the surface you probably have 0 nitrite. It may be the same for nitrate.

 

[Naughts]

I have a rapidly bubbling sponge filter rated at 65 gallons, in this 30 gallon tank, not sure how long it takes to colonize a twice size filter like that,

The same time as any filter. Cycling time is subject to variables, particularly in parameters. However the amount of bacteria is related to the amount of nitrogenous compounds in the tank, which is dictated by the fish (and it's diet plus your tank maintenance). Your acara fish produces the same amount of nitrogen, thus the same amount of beneficial bacteria, irrespective of what filter you use.

 

[Magnum Man]

I would suspect, that if I had a 10 gallon rated sponge filter in a 30 gallon, or this filter that is rated at more than double the gallon size... that there are major difference in prime real estate for the bacteria, and increased flow volume, as the tube diameter is bigger... curious how much difference there would be in the actual time required to build an acceptable colony

 

[Naughts]

I would suspect, that if I had a 10 gallon rated sponge filter in a 30 gallon, or this filter that is rated at more than double the gallon size... that there are major difference in prime real estate for the bacteria, and increased flow volume, as the tube diameter is bigger... curious how much difference there would be in the actual time required to build an acceptable colony

Remember the beneficial bacteria live on any hard surface, not just the filter.
The BB "eat" nitrogenous compounds, when "food" increases there are more, when it decreases, there are less. The main factor is the number and size of the fish as they are respiring and excreting the nitrogen.

 

[TwoTankAmin]

There are not a lot of consderations as to wheer in a tanks the bacteria can thrive. The first consideration is circulation. They live in a bio-film which is attached to hard surfaces. So everything they need must be delivered to them. But, they are somewhat photophobic, so they will onlly be found in darker places like in filter media, in the substrate, but only where oxygenated water can reach. They may be found on the undersides of things and they also are found on plants.

They are normally not found in the substrate at a depth of an inch unless they are in a planted tank with roots reaching into anaerobic zones. Some plants will actually transport oxygen down to their roots and then relaease it into the substrate. This creates aerobic areas which in turn foster bacterial growth. That usually leads to anaerobic denitrification zones above and or below which then use the nitrate created by the bacteria.

Petersen, N.R. and Jensen, K., 1997. Nitrification and denitrification in the rhizosphere of the aquatic macrophyte Lobelia dortmanna L. Limnology and Oceanography, 42(3), pp.529-537.

Full paper here https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.1997.42.3.0529