What are "stable" parameters?

[HawkeyeDJ]

I read almost everywhere that "stable parameters" are key to a successful reef tank, but I'm not sure anyone has defined what "stable" actually means.

For example, my 24g nano AIO is almost a year old. I have data from every week since the beginning.

My salinity fluctuates between 1.024 and 1.026. Is that "stable"?
Calcium fluctuates from 400 to 440.
Alk goes from 8-10.

Temperature from 77.0F to 78.0F. Occasionally it will dip to 76F during weekly water changes.

My goals at the one year mark are to add a nem and begin loading the tank with softies (already have GSP and xenia).

Is this tank ready and stable?

 

[Dom]

Stable parameters are tank parameters that have little fluctuation. The less fluctuation, the more stable.

In terms of what "good" parameters are, I don't feel there is any perfect answer. Yes, we have textbook definitions of what parameters should be. But in the end, the parameters of your tank should cater to your inhabitants and what they like.

As a general example, parameters in a fish only tank will be different than those of a reef tank. In a reef tank, things like calcium and carbonate are critical for healthy coral. In a fish only tank, not so much as there are no coral and we don't concern ourselves with those parameters as much.

 

[ying yang]

As already said " stable" means dont shift to much from your desired target amount .
But I read alot of dont chase numbers so have a target field like example nitrates 10- 20 so if nitrates are between 10- 20 then you hit your target .
Others target maybe greater and if nitrates are between 5 and 50 then ok.
Imo its all about finding what works in your tank best for you then set them as your targets.

I read often 0.03 -0.1 p04 and 5-10 ppm n03 is a good target field to aim for but im still learning as only 9 months Into first tank ^_^

 

[SeaworthyAquatics]

The salt and alk swings concern me. If this is across a week, it's fine for softies, nem might not do well with the alk swing though. Same with the temp swing during water change, some nems may not handle it well depending on what you type you're going for. The closer you can get your water change water to your temp/alk/salinity the better

 

[Aqua Man]

My salinity fluctuates between 1.024 and 1.026. Is that "stable"?
Calcium fluctuates from 400 to 440.
Alk goes from 8-10.

Stability to me is my tests from one to the next are very close.

Smaller tanks are sometimes harder to keep stable. Do you have an ATO? Really helps keep salinity stable.

 

[ID-Reefer]

I think everyones answers may differ but in general the less fluctuations the better. I would say your DKH and salinity fluctuations are more than I would want. Probably more difficult to avoid with in a 24 gallon tank however? I have a 250 gal. system so my salinity stays constant at 1.025. DKH swings in my tank are rarely ever more than .5 over the course of a week. Calcium fluctuations in my system are around 10-20 over a weeks time. Same with Mg.

My PH will go up and down quite a bit 8.27 up to 8.5 per Apex during a 24 hr. period.

Slight temp swings 77-79 are not a big issue in my opinion as that happens on an ocean reef.

Its a challenge to keep things stable as possible and most say chasing numbers is the wrong approach and even harmful. I mainly watch DKH daily and adjust dosing as needed during the week. A friend of mine who has two really successful Nanos doesn't do any testing other than salinity.

My system is a mixed reef with SPS, LPS, softies, fish etc... I think fluctuations are more forgiving if you are doing fish only or fish with softies...

 

[mattdg]

Agree with the above... stable is simply keeping your parameters from swinging back and forth. This can take some time to accomplish in a new system, as your coral (especially SPS) are growing into colonies. Definitely a moving target for the first few years. During this time, the coral that actually survive, will be the ones that will be able to handle whatever your version of stability ends up being. I'd say a fluctuation of 8-10 is really pushing it. With that said, I have had my Alk drop pretty low, brought it up slow and everything survived. Every system is different, but I do think that in general, the closer we get to a stable environment, the more colorful and better off our coral tend to be. On the flip side, coral that become accustomed to rock solid stability for a long period, will react more negatively to a parameter swing. No easy answers in this hobby.

 

[Rmckoy]

As mentioned above stability is little fluctuations .

for example :
My system alk is 7.5 dkh
I test daily and dose to compensate consumption .
salinity is always the same , 1.026 but over time as the skimmer cup fills the ato maintains the same level in the sump adding freshwater which will eventually lower the salinity .
Cal is always at 425

 

[Paul B]

Hawkeye, Yes, your parameters are stable enough. Mine vary many times more than that. Last week my salinity was so low I could keep bull frogs. I realized it and dumped in a bunch of salt over a couple of hours to bring it up from 1.015 to 1.025. That isn't what I suggest but just showing it isn't a big deal as many people feel.

Temperature is another one that isn't a big deal. It can fluctuate 5 or 6 degrees over the course of a day with no problems and many fish in the sea in channels or estuaries undergo that every day. Especially in the rainy season.

Calcium and alk can fluctuate wildly with no problems. Of course it is probably better if you can keep these parameters stable, but an occasional shift won't hurt anything and in some cases be beneficial.

 

[muzikalmatt]

As others have mentioned already, the specific definition of "stability" depends on the parameter in question as well as what corals you are trying to keep. Softies and LPS can tolerate larger alkalinity and even salinity swings, while SPS especially acropora will not.

For me, I would target the following "fluctuations".

• Temperature: I would try to keep your swings to less than a single degree throughout the day. With a temperature controller (like an Inkbird) and a good heater this should be easily achievable.
• Salinity: Ideally, salinity should not deviate from your target specific gravity at all. (i.e. If you're targeting 1.025 it should stay locked at that salinity at all times.) Any salinity swing (even just 0.001 SG) affects all of your other tank parameters so you want to keep this as stable as possible. With a well-functioning ATO, this should not be an issue.
• Alkalinity: Ideally, alkalinity should not swing more than 0.5 dKH in a day or 1 dKH in a week. This parameter will be a moving target as your corals grow and your consumption rate changes. At first, water changes will probably be enough but eventually you'll have to use something to keep up with the consumption (dosing or a calcium reactor).

The three above are in my opinion the most important to maintain stability as they are the most likely to change quickly over time. Nitrates and phosphates generally won't change as much day to day, especially as the tank matures. What's most important with those is to note the trends to see if they are trending upwards or downwards so you can take action as needed (and definitely don't let them bottom out). Similarly, fluctuations in calcium and magnesium will happen slowly and if you're keeping on top of your alkalinity with water changes, dosing or a calc reactor, generally they will be stable as well.

 

[((FORDTECH))]

I read almost everywhere that "stable parameters" are key to a successful reef tank, but I'm not sure anyone has defined what "stable" actually means.

For example, my 24g nano AIO is almost a year old. I have data from every week since the beginning.

My salinity fluctuates between 1.024 and 1.026. Is that "stable"?
Calcium fluctuates from 400 to 440.
Alk goes from 8-10.

Temperature from 77.0F to 78.0F. Occasionally it will dip to 76F during weekly water changes.

My goals at the one year mark are to add a nem and begin loading the tank with softies (already have GSP and xenia).

Is this tank ready and stable?

In no way on any planet is your salt fluctuation like that considered stable !!! I stopped reading right after I read that

 

[wmb0003]

In no way on any planet is your salt fluctuation like that considered stable !!! I stopped reading right after I read that

I agree, the salt fluctuation is quite large. What is the time frame? What are you using to test salinity? Do you have an ATO or how do you manage evaporation and trying to keep salinity on target?

 

[Mr. Mojo Rising]

stable means it stays the same. If the salinity is 1.030, the corals will get used to it, if temp is always 81, corals will get used to it, if phosphate always at .25, corals will get used to it.

Corals will acclimate to good water or not-so-good water, if the parameters always stay the same, thats what stability means IMO

 

[Rmckoy]

stable means it stays the same. If the salinity is 1.030, the corals will get used to it, if temp is always 81, corals will get used to it, if phosphate always at .25, corals will get used to it.

Corals will acclimate to good water or not-so-good water, if the parameters always stay the same, thats what stability means IMO

Exactly ….
Not chasing a specific number but maintaining that number stable !

 

[tharbin]

Stability is more about fluctuation over a time period than absolute numbers. A change from 1.026 to 1.024 over a day is not stable a fluctuation from 1.026 to 1.024 over a year is very stable. Most parameters will vary from time to time the goal is to make those changes very gradual. That is one reason for the old adage of buying the biggest tank you can afford. It takes longer for changes to affect the system.

In small tanks there will always be some fluctuations. It doesn't take much evaporation to cause a 0.001 sg swing in a 10 gallon tank. So if you have a small tank an ATO is usually a good idea.

I don't really buy into the temperature stability narrative. Water temps are constantly changing on the reef. A decent heater can keep your tank plus or minus 1.5 degrees easily. That should not be problem for any of your inhabitants.

Big alk swings or sg swings probably cause the most system stress.

Phosphate and Nitrate are the dreaded necessary evils. Too much - algae, too little - algae and no coral growth. I don't know that there are really universally "good" numbers for them I think every tank is just a little unique from every other tank. Pick someone who's tank you admire and try their numbers to see if they work for you.

 

[HawkeyeDJ]

I may have been unclear in my OP.

The fluctuations I mentioned quite often occur over several weeks or even months. For example, my salinity might be at 1.024 for three weeks, then I'll it at 1.025 then in two weeks it might drop to 1.024 again or rise to 1.026.

What I'm hearing some of you say is whatever the number is, it is important, even critical, that number remain the same at all times. Have I got that right?

The same with my alkalinity. Over a period of several weeks/months it has gone from 8 to 9, 10, 11 and back down to 9 then back to 10 over the same period. These are not rapid fluctuations, are they?

And if these fluctuations are a concern, then can I conclude that after 10.5 months the tank is simply not stable enough to be called "mature"?

And for those who asked, yes I have an ATO. It has a 1.5 liter reservoir which gets refilled about twice a week with RO.

 

[Dom]

In no way on any planet is your salt fluctuation like that considered stable !!! I stopped reading right after I read that

That fluctuation is probably the result of evaporation and then topping off. I'd guess that there isn't an ATO involved.

 

[Spare time]

I read almost everywhere that "stable parameters" are key to a successful reef tank, but I'm not sure anyone has defined what "stable" actually means.

For example, my 24g nano AIO is almost a year old. I have data from every week since the beginning.

My salinity fluctuates between 1.024 and 1.026. Is that "stable"?
Calcium fluctuates from 400 to 440.
Alk goes from 8-10.

Temperature from 77.0F to 78.0F. Occasionally it will dip to 76F during weekly water changes.

My goals at the one year mark are to add a nem and begin loading the tank with softies (already have GSP and xenia).

Is this tank ready and stable?

I'd say its fine. You can get a small heater to help heat the water for water changes if that is a concern.

As for alk swings, I think the bigger issue is how much you dose at once which in turn causes pH swings, as I don't see how the swings in alk itself would impact things as much.


It also depends on the test kit you use. Some are more precise than others.

 

[HawkeyeDJ]

That fluctuation is probably the result of evaporation and then topping off. I'd guess that there isn't an ATO involved.

No, there is an ATO on the tank and has been for many months. If anything, it could be due to the water changes as I haven't yet figured out how to replace the exact amount of water I've removed. If I pour a half pint more or less water in than I removed, would that be enough to swing the SG a full .01?

 

[adittam]

I may have been unclear in my OP.

The fluctuations I mentioned quite often occur over several weeks or even months. For example, my salinity might be at 1.024 for three weeks, then I'll it at 1.025 then in two weeks it might drop to 1.024 again or rise to 1.026.
...
And for those who asked, yes I have an ATO. It has a 1.5 liter reservoir which gets refilled about twice a week with RO.

That fluctuation is probably the result of evaporation and then topping off. I'd guess that there isn't an ATO involved.

sequential posts...lol...<sigh>