Water Changes: What "percentage" makes it worth doing?

What water change "percentage" makes it worth doing?

  • 5% - 10%

    Votes: 95 9.7%
  • 10% - 20%

    Votes: 512 52.0%
  • 20% - 30%

    Votes: 232 23.6%
  • 30% - 40%

    Votes: 30 3.0%
  • 40% - 50%

    Votes: 22 2.2%
  • 50% or more

    Votes: 14 1.4%
  • No water change is worth it

    Votes: 36 3.7%
  • Not sure

    Votes: 19 1.9%
  • Other (please explain in the thread)

    Votes: 24 2.4%

  • Total voters
    984

carbasaurus

Active Member
View Badges
Joined
May 23, 2021
Messages
147
Reaction score
218
Location
carlsbad
Rating - 0%
0   0   0
It depends on what you are trying to accomplish and just comes down to simple math. If your goal is to reduce nitrate and say your nitrate is 40, a 20% water change only gets you to 32. You would need to do very frequent water changes at that volume to have a meaningful impact. There are other better ways to reduce nitrate load.

If your purpose is to replace trace elements for coral health then maybe 20%???? But even for this purpose it’s just guess work without advanced testing.

I still do water changes periodically despite my above comments. It’s an excuse to vacuum up any Cyanobacteria lurking in crevices, clean up the sand, give a good flush of the dead zones, clean the sump and inspect all my gadgets
 

Paul B

10K Club member
View Badges
Joined
Nov 3, 2010
Messages
17,948
Reaction score
60,752
Location
Long Island NY
Rating - 0%
0   0   0
I have always felt that to many water changes or changing to much water was detrimental to tanks as water, within reason gets better with age. That is one reason older tanks have no problems and new tanks with all new water look lousy and are never healthy.
 

RicksRed66

New Member
View Badges
Joined
Mar 26, 2020
Messages
3
Reaction score
31
Rating - 0%
0   0   0
As anyone heard of doing a 80--90% water change? my " Fish Guy" did that to our reef tank & it seemed a bit too drastic a change...
 

beaslbob

2500 Club Member
View Badges
Joined
May 11, 2009
Messages
4,086
Reaction score
960
Location
huntsville, al
Rating - 0%
0   0   0
As anyone heard of doing a 80--90% water change? my " Fish Guy" did that to our reef tank & it seemed a bit too drastic a change...
While it is possible to maintain a tank through water changes, it's not practical for the average hobbyist hundreds of miles from the ocean. To those people a balanced out ecosystem is the only practical method.

But if you live on the beach and can constantly recirculate ocean water, go for it.

my .02
 

carbasaurus

Active Member
View Badges
Joined
May 23, 2021
Messages
147
Reaction score
218
Location
carlsbad
Rating - 0%
0   0   0
As anyone heard of doing a 80--90% water change? my " Fish Guy" did that to our reef tank & it seemed a bit too drastic a change...
I read in Coral Magazine a few years back that people keeping pico reefs (like 1 gallon systems) do just that. Once a week they would feed the corals then do basically a full exchange. Some of these tiny reefs even had sps corals. The trick of course is making sure salinity, pH and temperature are matched
 

Stigigemla

Well-Known Member
View Badges
Joined
Mar 20, 2015
Messages
902
Reaction score
827
Location
sweden
Rating - 0%
0   0   0
I can see 3 reasons to make a water change.

1. If there is too much of anything like Nitrate or phosphate a big water change can reduce the value of it.

2. If something is depleated like a trace element You can often notice a change 2 days after a small water change like 10%. 10% of an element is more than a 1000 times more than zero.

3. It can make the owner feel good because a good thing for the tank has been done. That works even when the water change was unnecessary.
 

Joekovar

Active Member
View Badges
Joined
Jan 22, 2020
Messages
309
Reaction score
335
Location
Tampabay
Rating - 0%
0   0   0
I change 10G in my 55G every weekend after stirring up the sand bed and hitting low flow areas with a toothbrush.

If I don't, I get algae outbreaks that take 1-2 months to get rid of.
 

Gup

Active Member
View Badges
Joined
Jan 11, 2021
Messages
394
Reaction score
271
Location
Wildwood
Rating - 0%
0   0   0
I am lazy and use the APEX DOS to do it for me. I change 5 gallons a day during the over night hours on a 675 gallon tank, works out to about 20% a month. All I do is mix salt once a week. I believe the tank is as stable as it ever has been.
Of course, it's whatever works for you or each one of us for that matter

But I have a serious question. If you change 5 gallons every day, you're pulling out completely good water everyday. Granted, it is miniscule, nevertheless you are still draining healthy, good water molecules, not to mention the nutrients embedded with your fresh salt. No?
 

Gup

Active Member
View Badges
Joined
Jan 11, 2021
Messages
394
Reaction score
271
Location
Wildwood
Rating - 0%
0   0   0
My 55 gallon is 6 months new. My wife and I have the water changes down to a science now. The drain and refill requires just under 20 minutes. I'm still changing 20 gallons every 4 - 5 weeks. Depending on our availability.

The day prior, it takes me about 20 minutes with the setup of the new water.
 

Gup

Active Member
View Badges
Joined
Jan 11, 2021
Messages
394
Reaction score
271
Location
Wildwood
Rating - 0%
0   0   0
I change 10G in my 55G every weekend after stirring up the sand bed and hitting low flow areas with a toothbrush.

If I don't, I get algae outbreaks that take 1-2 months to get rid of.
Would you consider Dino X? I used that after just a couple months, and it right up. I did just develope a red cyno problem about a month ago. I used the red cyno Chemiclean & it cleared that problem up in 4 days.
 

Joekovar

Active Member
View Badges
Joined
Jan 22, 2020
Messages
309
Reaction score
335
Location
Tampabay
Rating - 0%
0   0   0
Would you consider Dino X? I used that after just a couple months, and it right up. I did just develope a red cyno problem about a month ago. I used the red cyno Chemiclean & it cleared that problem up in 4 days.

Would you consider Dino X? I used that after just a couple months, and it right up. I did just develope a red cyno problem about a month ago. I used the red cyno Chemiclean & it cleared that problem up in 4 days.

The main good that comes with regular water changes vs chemical reactions for me is removing things in multiple stages of decomposition because I'm stirring everything up pretty well before pulling water out.

Whereas with chemicals specific stages of decomposition get targeted for chemical reactions.

If I didn't emulate strong tides, storms, and other weather by stirring everything up periodically, some of the higher up in the food chain elements would build up and eventually overwhelm some stage of the system when they finally break down.
 

beaslbob

2500 Club Member
View Badges
Joined
May 11, 2009
Messages
4,086
Reaction score
960
Location
huntsville, al
Rating - 0%
0   0   0
Of course, it's whatever works for you or each one of us for that matter

But I have a serious question. If you change 5 gallons every day, you're pulling out completely good water everyday. Granted, it is miniscule, nevertheless you are still draining healthy, good water molecules, not to mention the nutrients embedded with your fresh salt. No?
yes.
what happens is that system builds up to where the waterchange removes the build up between changes. you change 1/10 of the water it builds up 10 times the change. 1/20 20 times. 1/5 5 times and so on.
the best thing is to limit the buildup .
 

Randy Holmes-Farley

Reef Chemist
View Badges
Joined
Sep 5, 2014
Messages
66,539
Reaction score
62,828
Location
Arlington, Massachusetts, United States
Rating - 0%
0   0   0
Of course, it's whatever works for you or each one of us for that matter

But I have a serious question. If you change 5 gallons every day, you're pulling out completely good water everyday. Granted, it is miniscule, nevertheless you are still draining healthy, good water molecules, not to mention the nutrients embedded with your fresh salt. No?

I'm not sure what a good water molecule is vs a bad one, but doing 6 changes of 5% each does exactly the same as one change of 26.6%.

Thus, it doesn't matter that much how you change 20-30% per month. Even 300 changes of 0.1% each is nearly the same (like one 25.9% change).

.
 
Last edited:

Daniel@R2R

Living the Reef Life
View Badges
Joined
Nov 18, 2012
Messages
37,364
Reaction score
63,251
Location
Fontana, California
Rating - 100%
1   0   0
Dear Abby,

I was told that water changes have a positive effect on my aquarium but what percentage of water should I change to make it worth it?

Sincerely,

Confused Reefer


image via @Reef Hacks and their Exploring Water Changes article.
Reef-Tank-Water-Changes.jpg
Hmmm...I'd say it depends on how often you change it. If once a week, I'd say at least 10%. If once per day, make it at least 1-2%.
 

A worm with high fashion and practical utility: Have you ever kept feather dusters in your reef aquarium?

  • I currently have feather dusters in my tank.

    Votes: 73 37.6%
  • Not currently, but I have had feather dusters in my tank in the past.

    Votes: 66 34.0%
  • I have not had feather dusters, but I hope to in the future.

    Votes: 25 12.9%
  • I have no plans to have feather dusters in my tank.

    Votes: 28 14.4%
  • Other.

    Votes: 2 1.0%
Back
Top