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Discussion Starter · #1 ·
Hello all,

I'm new to the aquarium community and am trying to get some reliable information regarding cycling.

I currently have a 5 gallon planted tank (fluval spec V) which is generally doing well. It has been running for a few weeks. Unfortunately, I didn't have the opportunity to cycle this tank at all. The tank ran for about three days with plants only (and prime treated water) and then a betta was added. I do not see any signs of stress and the fish generally seems happy.

My understanding was that the tank must be cycled before fish are added. I am aware of fish-in cycles as well. Recently, I've been reading that tanks under 10 gallons do not cycle, or do not require cycling. I've read that water changes never allow the bacteria to grow effectively when the tanks are this small, leading to unstable conditions. Is this the case?

With the rise of the nano and desktop tank, I find some of this information hard to believe. Will my tank crash? Should I be doing more water changes? Do smaller tanks require more water changes/cleaning/maintenance than larger ones?


Also, I am awaiting a liquid test kit, but my parameters (using test strips) are reading 0.5ppm nitrite and 40ppm nitrate, with moderately hard water and a neutral pH. I'm trying to figure out what I am supposed to be looking for in these parameters. I realize that the nitrites should be 0 and am doing regular 50% water changes.

Thanks,
T

P.S if anyone has a similar 5-10g planted setup, what is your maintenance schedule?
 

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Many of these questions relate to how we each may not speak as precisely as needed or we shift the terms just a touch.
So this is my view and may not fit others. I say a tank will "cycle" regardless of what we do, but only to a certain point and that is where we need to be a bit more specific and understand what I believe to be the early meaning of the term, "cycle".
My idea of cycle is when the waste is being converted from the early stages of decay where it is ammonia, to nitrite and finally to nitrate. Many might think of the cycle as being when it is safe to add fish! Some of the early use of the cycle was to set a tank up to receive a shipment of fish all at one time to save multiple shipping charges. So fishless cycle became common practice as a way to build a large bacteria colony to meet a sudden increase of fish load.
After getting into planted tanks, I've seen the term morph quite a bit to mean many differing levels of doing the same to make a tank ready for fish and that has led to many differing ideas of what we want and how we get there.
So the question may be as much about what each person wants and how he wants to get there.
To me the cycle is getting the tank ready for what we want to do. So a tank CAN be ready if the owner is also ready to make it work. A tank doesn't have to have much bacteria ready to convert very much waste if there is a lot of water and very little waste to be diluted to safe levels.
That explains why some may say a small tank doesn't cycle as they never see any ammonia as they are simply not able to measure the extremely low ammonia levels from a couple small fish. This is especially true if they are also doing large percentage water changes to remove/dilute much of the waste and ammonia.
So my answer is that a tank will cycle but we may not see it and it is also only cycled to the level of waste we are producing, not that it is ready to add a shipment of fish. A tank can set for months/years with a small load and be totally cycled for that load but certainly not cycled to add twenty more fish all at once!
Water changes will not change the amount of bacteria growing but that is assuming those changes are done correctly so that we are not killing the bacteria.
When I first started in the game, we did not cycle a tank, but simply scrubbed it all down with the hottest water we could stand and totally killed all the bacteria we might have grown! The price we paid for this lack of knowledge was doing a vast amount of work and seeing the fish occasionally die----for some unknown reason! The thinking was that we must have missed some disease in the tank and we should scrub better next time or use hotter water.
Knowledge is such a precious thing!
 

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As far as the bacteria needed to convert ammonia and nitrite to nitrate as long as sufficient minerals and food ammonia) pressent in the tank bacteria will grow and the tank will definitely cycle. As to maintaining a stable PH, KH, and GH that will depend on the number of fish and how you maintain your tank. It is possible to keep the parameters stables in a small tank but it might be a little more difficult than it would be in a larger tank.
 

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I might guess that some of the confusion about small tanks not doing a cycle could just be the way we test for ammonia, nitrite and nitrate. When we have a small tank and small load of waste, it might be pretty easy to miss having ammonia and seeing it turn to nitrite and on into nitrate as our testing is not really too precise and then if we throw in having plants to further suck nutrients from the water. So those who might say they don't cycle may just be not looking far enough to find nitrate and jumping to the idea that they never had ammonia and never had nitrite, it didn't cycle. They might be hard pressed if asked about nitrate but then if there are plants, they may not see that either.
Very easy to find the wrong idea if we don't look close enough. One of the really good points of doing a fishless cycle is that we DO know there is X amount of ammonia as we add it, then when we see nitrite being processed to nitrate and add more ammonia, we can say with pretty good assurance that the cycle is complete! It may just be part of our impatient nature and trying to short cut the waiting that makes us come around to the tank doing something else.
 

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All tanks cycle to a degree....or not. Aerobic beneficial bacteria colony(ies) are relative to the available food supply and oxygen. Nitrosomonas converts ammonia into nitrite and nitrospira converts nitrites into nitrates. HOWEVER, in a small planted tank, or even a larger heavily planted tank, the development of the BB may be inhibited. Why? Plants will use ammonia as their nitrogen source so with little bio-load, the plants may use the ammonia instead of BB. This is a good thing, as it results in lower nitrates.
I have an experienced hobbyist/friend that never cycles a tank per se....because he has fast growing plants that handle much/most of the ammonia and he initially stocks the tank low. Oh BB eventually develops, but to a much lesser degree than might otherwise be the case.
In any case, tank size is irrelevant relative to the nitrogen cycle.
 

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Discussion Starter · #6 ·
Wow! These are all very thorough responses. Thanks for sharing your knowledge! I think I can see why there are misconceptions about tank cycling as well. Thankfully these responses helped clear these up!
 

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The idea of "cycle" is still one that gets lots of conversation going and it still slips up on us at times. The worst case may be when we have a tank for a long time and we've had fish in it long enough that we are certain that it has totally completed any "cycle". So thinking it all done, we order a big box of our favorite fish and fine we don't have near enough good bacteria built up to handle a load that may now be four times as large! There are tanks cycled and ready for one fish, six fish, or 20 fish but they are not all the same!
 

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Wow! These are all very thorough responses. Thanks for sharing your knowledge! I think I can see why there are misconceptions about tank cycling as well. Thankfully these responses helped clear these up!
While I did a fishless cycle with minimal plants by adding small controlled doses of ammonia, few have the patience to do this.

Bettas are very hardy fish if you had any ammonia it wouldn't bother them as much as other fish, look how the fish stores keep them in little cups. If you are feeding sparingly 1 betta with heavy planting the plants should consume the ammonia. That doesn't mean the tank isn't developing BB and doesn't mean the cycle isn't completing.

If you plan to add more sensitive fish, wait a few more weeks and do so slowly. Getting an API Ammonia kit and testing will help, don't do a water change for 2 - 3 days and then check your Ammonia, if you don't have any or 0.25(test is poor at distinguishing between 0.25 and 0) you are fine. Classicly if the cycle is completed you should have 0 Ammonia 0 Nitrites and be building up nitrates slowly. However given you have plants and a low bioload you may never see the nitrates build up.
 
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