Newb question: What exactly is a 'mature' tank?

As I read and research, I keep coming across the recommendation that you have a 'mature' or 'well established' tank for certain corals, inverts, etc. I realize this means, generally, a tank that has been up and going for six months to a year or more, depending on who you ask... but why? It seems to have something to do with having a strong biofilter, but I don't completely understand what makes it so much stronger over time if the ammonia input/nitrate output is pretty much the same throughout those six months to a year. Does something over time make these bacteria more 'hardy'? Is there something else about the concept of a 'mature' tank that I'm missing? I'm very curious!

Im no expert but generally  a "mature" tank refers to a tank at least 1 year old. The actual age of the tank really isn't significant but really the time for all the healthy biologicals to develop. The amount of bacteria and microfauna in a 4 month old tank will be greatly less than in a properly established/maintained 1 year old tank.

The age of the tank ultimately does not determine it's state of stability ( maturity )

A mature tank is a tank that has reached a balanced, saturated level of beneficial bacteria, micro fauna, and all other forms of life in the reef. Often times this includes micro-organisms that we can't see, nor can we track.

Populations have a direct correlation to available food. Once the food/bio-life ratio has met equilibrium a tank can be considered "mature." At this point, waste is efficiently processed through the bio-filtration, and the mortality rates of all organisms is in balance with their "birth" rates. 

Below is a very basic graph I threw together demonstrating a standard population growth model. The "Desired Population" is what the population will be when everything has met an equilibrium. As time goes on, the population level gets closer and closer to equilibrium.




The longer amount of time that you have, the more likely it is for a population to reach stability. 

The introduction of certain populations can decrease the time it takes to reach biological stability, in this case referred to as maturity. This is why people add bottled bacteria, live rocks, live sand, copepods, amphipods and other micro organisms to their systems to get the cycle going faster.

Ultimately nothing can instantly cycle or mature a reef tank. You can however instantly bring the cycle within tolerable ranges for fish and invertebrates with the introduction of organisms if adequate populations are introduced.

Any major swings in your reef can cause a disruption in the balance, which can cause a population destruction that effects all of the populations in the tank ( tank crash etc ). Swings in water conditions will have a negative impact on the stability of your reef. That's why it's important to have a light schedule, an auto top-off, a regular feeding schedule and regular water changes.

That's my best shot at explaining it over the forums without going too in-depth. If you want to get into the finer details, shoot me a PM.

Edited by Pete Moss - March 16 2015 at 12:41pm

You're welcome! Next time you're over come loaded with all these questions and you can pick my brain hahaha.

Mark Peterson wrote: That's a good explanation John. I have also found that it differs according to the setup. If LS, LR, Macroalgae and LW from another good tank are used from the start and the bioload of fish is added slowly and conservatively, then it is sort of a gradual ramp up in biofiltration toward maturity as CMcTay was thinking.  IMO, there is no perfect spot, but there is a balancing act all along the way as your graph illustrates.  The 75 gallon expansion to my coral farm was set up with lots of live stuff and there was No Cycle, No brown algae and no high pollution levels. Granted, I used a fair amount of the four live components because I have access to lots of that stuff. I also turned on the lights 24 hrs/day for the first week which powerfully ate up pollution. The Macroalgae grew fast.  I don't typically recommend beginners move this quickly.  But for the record, I added 3 fish at day three; 4" Yellow Coris Wrasse, YT Blue Damsel, 5" Lawnmower Blenny. All are healthy and happy three weeks into the life of this setup. Aloha, Mark  MarksReef Coral Farm

Naturally there is no "perfect spot" as conditions would have to remain absolutely constant for their to be a true stabilization, which is never going to happen in a reef tank.

I already mentioned you can add live rock and live sand from other setups to "fast forward" through time to achieve stability sooner.

You introduced a 75 gallon aquarium into a system of over 200 gallons. Of course it was ready for fish quickly. I promise you still had a cycle, if you ran tests every day you would have seen it. The cycle was just within tolerable ranges for the health of your fish. ( small bumps on the graph )


Edited by Pete Moss - March 17 2015 at 7:57am

Have you ever seen a virus with your own eyes? Ever seen a million bucks? Those still exist.

There is science behind the cycle Mark, it's not a mysterious fable fostered from generations of hand me down stories. Science is cool, because whether you believe it or not, it's true.

There is a bacteria population in your tank. They need oxygen and ammonia, it's their "food." When that food is depleted there is a spike in bacteria. The lack of food and overpopulation of bacteria causes a certain amount of die-off, which feeds ammonia back into the tank. Then we are back at square one which is why it's called a "cycle"

If you introduce the right amount of bacteria to your system, you can avoid the worst part of the cycle of course. But if any "dead" rock or sand enters the tank, even when a new fish enters the tank, there is a small cycle. Always.

EDIT: Algae helps absorb excess nutrients, but isn't a cure-all fix-all. It can't "eat" nitrates and phosphtaes the minute they enter the water column. Fun read for those interested.

Either way I'm done with the discussion. Don't want the presidency getting swarmed with more messages hahaha.


Edited by Pete Moss - March 17 2015 at 3:48pm

FYI: Most of the time when I see the terms "Mature Tank", "Stable Tank", or "Well Established Tanks" it is in relation to a specific fish (or invert).

While the previous explanations are accurate...What they (LFS, web site, etc.) are really saying is, "Make sure there is enough natural food available". That typically comes with having a well established or stable tank.

For example, if you are looking at a Mandarin Goby:
They usually feed on live food (Copepods, shrimp, etc.). So, "they" will say a mature stable tank. Because, these live foods are most likely only growing in a mature stable tank.