What's the "magic" of 10% weekly water changes?

[mike550]

Hello! As I continue to learn about ways to keep my tank healthy, water changes are certainly an interesting topic.

Trying to keep some focus on this, but I know a lot of folks suggest 10% weekly water changes. My question is why 10%?

Why wouldn't you do a 15% or 20% weekly water change?

Is this more about making sure the changes aren't too drastic?

Truly a newbie question, but really trying to understand. Thanks in advance!

 

[Webslinger]

removing bad, putting in good, keeping everything stable. No need to dose
15 - 20 stability changes.


Stable and slow/steady wins the race.

 

[Randy Holmes-Farley]

Expense and work are two reasons to not change more. I show what these sorts of changes accomplish here:

Water Changes in Reef Aquaria by Randy Holmes-Farley - Reefkeeping.com

http://reefkeeping.com/issues/2005-10/rhf/index.php

 

[Crustaceon]

It’s a balance of removing excess nutrients and trying to maintain stability. A 10% weekly water change is widely considered “safe” while a 20% water change has a greater chance of creating a rapid shift in water parameters, which can be harmful to our critters. The more we change, the closer we have to come to matching our display’s water parameters with the water we plan on putting back in. That’s tricky.

 

[X-37B]

The magic is, its simple, easy to do, cost effective and it works!
Make sure your change water matches your tank water in terms of temp, SG, alk, and your good to go.

 

[Webslinger]

It’s a balance of removing excess nutrients and trying to maintain stability. A 10% weekly water change is widely considered “safe” while a 20% water change has a greater chance of creating a rapid shift in water parameters, which can be harmful to our critters. The more we change, the closer we have to come to matching our display’s water parameters with the water we plan on putting back in. That’s tricky.

That's what i said

 

[mike550]

Expense and work are two reasons to not change more. I show what these sorts of changes accomplish here:

Water Changes in Reef Aquaria by Randy Holmes-Farley - Reefkeeping.com

http://reefkeeping.com/issues/2005-10/rhf/index.php

@Randy Holmes-Farley thanks for sharing this! It certainly helps me understand why I had to start doing two-part.

One question from your article. You say, "If there is substantial ammonia in the new water, as there may be in artificial salt water or possibly in natural seawater that has been stored for a while, that can also be stressful." I never thought about my new saltwater having ammonia. Is ammonia created while storing "new" saltwater? If so, any thoughts on how long you can safely store the water? If it matters I am currently using TM Classic.

Thanks

 

[Randy Holmes-Farley]

@Randy Holmes-Farley thanks for sharing this! It certainly helps me understand why I had to start doing two-part.

One question from your article. You say, "If there is substantial ammonia in the new water, as there may be in artificial salt water or possibly in natural seawater that has been stored for a while, that can also be stressful." I never thought about my new saltwater having ammonia. Is ammonia created while storing "new" saltwater? If so, any thoughts on how long you can safely store the water? If it matters I am currently using TM Classic.

Thanks

Ammonia is not created in new salt water, but is often there as an impurity in some of the main ingredients. Usually the levels are pretty low, less than 0.2 ppm.

 

[Doctorgori]

Dumb and acedotal as it sounds but I’d almost swear you can see the difference after a 10% -15% change ... a larger one sometimes has the opposite effect (sometimes with emphasis)
....But I’m open to it being a placebo effect

 

[shadesatsetbreak]

I've never had any livestock go into shock because of too big of water change, and I've done 70%+ many times.
Sometimes, bucket size dictates how big of a change I do. I have a twenty (probably fifteen gallon volume) that I usually do five gallon water changes on because I can vacuum the sandbed for longer.
There's no definite rule, but nutrient levels should serve as your bare minimum water change capacity, and let cost serve as your ceiling. Don't overthink it.

 

[Waters]

There are nano vase tanks that do 100% water changes weekly with no issues. As long as your parameters match in the replacement water there shouldn't be an issue. The key is to just change enough to keep your nutrients where you want them.

 

[beaslbob]

FWIW water changes are kinda considered a cure all to most. And It does make sense. Out with the bad in with the good, the solution to pollution is dilution and so on.

Fortunately, it is something that on the most basic level can be analyzed mathematically.

Consider a system that has been running for some time and therefore has reached its end point. And that things are measured linearly and are constantly increasing or decreasing at a constant rate. (Calcium, ammonia, nitrItes, nitrates, phosphates are examples. PH is not because it is not linear). And that you do some percentage of water change, at the same interval and that water has constant values. What is the value of some parameter just before a water change?

Ans: before water change value=Value in replacement water+(increase between water changes/fraction of water change)

For example take nitrates in a system that increases nitrates at a rate 1ppm/day with a 20% (1/5) weekly water change with 15ppm nitrate replacement water.

The end point is 15ppm*(1ppm*7/(1/5)) =15ppm+7ppm*5=15ppm+35ppm=50ppm just before water change.

By contrast if you had sufficient nitrate consumers (macro an other algae) the change in nitrates would be 0. With 0ppm water, nitrates would be 0. With no water changes nitrates would be 0 always.

So to me what is important is to balance out the system to where water changes are simply not needed and the system basically takes care of itself.

But that's just me and my .02

 

[Webslinger]

FWIW water changes are kinda considered a cure all to most. And It does make sense. Out with the bad in with the good, the solution to pollution is dilution and so on.

Fortunately, it is something that on the most basic level can be analyzed mathematically.

Consider a system that has been running for some time and therefore has reached its end point. And that things are measured linearly and are constantly increasing or decreasing at a constant rate. (Calcium, ammonia, nitrItes, nitrates, phosphates are examples. PH is not because it is not linear). And that you do some percentage of water change, at the same interval and that water has constant values. What is the value of some parameter just before a water change?

Ans: before water change value=Value in replacement water+(increase between water changes/fraction of water change)

For example take nitrates in a system that increases nitrates at a rate 1ppm/day with a 20% (1/5) weekly water change with 15ppm nitrate replacement water.

The end point is 15ppm*(1ppm*7/(1/5)) =15ppm+7ppm*5=15ppm+35ppm=50ppm just before water change.

By contrast if you had sufficient nitrate consumers (macro an other algae) the change in nitrates would be 0. With 0ppm water, nitrates would be 0. With no water changes nitrates would be 0 always.

So to me what is important is to balance out the system to where water changes are simply not needed and the system basically takes care of itself.

But that's just me and my .02

That's too much math!

 

[beaslbob]

That's too much math!

I know I no. LOL

It took me from the late '70s till the first decade in 2000 to figure that out.

 

[mike550]

FWIW water changes are kinda considered a cure all to most. And It does make sense. Out with the bad in with the good, the solution to pollution is dilution and so on.

Fortunately, it is something that on the most basic level can be analyzed mathematically.

Consider a system that has been running for some time and therefore has reached its end point. And that things are measured linearly and are constantly increasing or decreasing at a constant rate. (Calcium, ammonia, nitrItes, nitrates, phosphates are examples. PH is not because it is not linear). And that you do some percentage of water change, at the same interval and that water has constant values. What is the value of some parameter just before a water change?

Ans: before water change value=Value in replacement water+(increase between water changes/fraction of water change)

For example take nitrates in a system that increases nitrates at a rate 1ppm/day with a 20% (1/5) weekly water change with 15ppm nitrate replacement water.

The end point is 15ppm*(1ppm*7/(1/5)) =15ppm+7ppm*5=15ppm+35ppm=50ppm just before water change.

By contrast if you had sufficient nitrate consumers (macro an other algae) the change in nitrates would be 0. With 0ppm water, nitrates would be 0. With no water changes nitrates would be 0 always.

So to me what is important is to balance out the system to where water changes are simply not needed and the system basically takes care of itself.

But that's just me and my .02

Thanks for your thoughts and I appreciate the impact of water changes. That said, are you saying that you can get a tank to where water changes aren't needed? I suppose it's possible to come close to equilibrium, but haven't thought about it this way.

I've heard about people using the Triton method (which I can't do based on the underlying requirements) which seems a lot like you're describing. But if you don't do water changes, then wouldn't you also need to have all sorts of other supplements that the "fresh" saltwater would provide?

 

[Webslinger]

Thanks for your thoughts and I appreciate the impact of water changes. That said, are you saying that you can get a tank to where water changes aren't needed? I suppose it's possible to come close to equilibrium, but haven't thought about it this way.

I've heard about people using the Triton method (which I can't do based on the underlying requirements) which seems a lot like you're describing. But if you don't do water changes, then wouldn't you also need to have all sorts of other supplements that the "fresh" saltwater would provide?

yep

 

[mike550]

yep

Interesting. So are you doing this? Would love to hear more details about how you've accomplished it

 

[Randy Holmes-Farley]

Thanks for your thoughts and I appreciate the impact of water changes. That said, are you saying that you can get a tank to where water changes aren't needed? I suppose it's possible to come close to equilibrium, but haven't thought about it this way.

Yes, you can.

It may be more expensive and more work, however, to be sure all needs are being met, whether that means adding things that are depleted and are useful or exporting things that are accumulating and may be detrimental.

 

[dbowman5]

IMO my tank has a lot of moving levels:
main ingredients and trace elements in the water
contaminants and nutrients
livestock, animal and vegetable
live rock and sand
heat/cold
flow
aeration
CO2
pH
Hardness
and STUFF I DON'T KNOW
I can not control all of it or want to. I believe there is a benefit to adding fresh SW to my system as well as keeping the evaporation losses replaced with FW. Where science meets art is where each hobbyist feels that his creation is optimized.
The 10% rule of thumb is a starting point. If I can get into a routine of maintenance and keep that up my life forms will benefit. If i set up an impractical standard and can't/won't keep it up my life forms will suffer. Plus the guilt will sour the enjoyment of the hobby.
the idea of picking one testable parameter to measure to control all the others is tempting. if i can do water changes and keep all the parameters within healthy ranges, can i afford the time, expense, and materials to do it? This is the balancing act you perform when you are caring for your Aquarium and the rest of your life.
if you change the diaper every ten minutes the chances of baby having diaper rash lessens, if you do, you throw a lot of clean diapers away. maybe check the diaper and if dirty change it. while changing check for rash and if found medicate it,
otherwise keep your nose open for hints that something needs to be done. lol

 

[X-37B]

Thanks for your thoughts and I appreciate the impact of water changes. That said, are you saying that you can get a tank to where water changes aren't needed? I suppose it's possible to come close to equilibrium, but haven't thought about it this way.

I've heard about people using the Triton method (which I can't do based on the underlying requirements) which seems a lot like you're describing. But if you don't do water changes, then wouldn't you also need to have all sorts of other supplements that the "fresh" saltwater would provide?

It can, has, and is being done. You need a plan and an understanding of what and how its done.
Its not for beginners imo.
Some water is always replaced to keep SG at the correct level.
Cleaning detrius and skimmer out, taking frags are ways to replace water.
Scheduled weekly 10% changes are what most talk about when talking water changes.
For most water changes are the norm and should be done as many tend to overstock their systems.
I have ran a no scheduled water change system on my 120 since day one.
Tank will be 1 year in a couple of weeks.
I will send out for icp testing to see what levels im at.
This will be interesting and I will post results and pics in my build thread.