View Full Version : How often does everyone changed the water?


Atlanta Aquarium
02-17-2008, 10:49 PM
Recently I bought a G-6 skimmer. It's a workhorse!!! I was thinking of changing my water once every two weeks or maybe even once a month.
Is this ok for a reel tank?

Victor626nj
02-17-2008, 10:51 PM
its been two months but im making a mix for tomorrow as we speak im getting good growth out of my corals eveything is colored up and i have about 20 fish ...so i dont think you have to do them that frequently

Atlanta Aquarium
02-17-2008, 10:56 PM
Two months? I think I overdone the water changes. I'm going to try to do less frequent water changes.

Barbara
02-17-2008, 10:57 PM
I change mine when the hair algae crawls out of the tank, walks upstairs, taps me on the shoulder and informs me that it's about to move in permanently! Seriously, I only change my water every 2 & 1/2 to 3 months. I call it my quarterly water change. My corals have good growth, fish don't die, skimmer works great, water doesn't stink. I can't see changing it any more often since I don't have problems.

LorenK
02-17-2008, 11:01 PM
How about this question...how do you know when you should change water?

There is a certain reefer who has a large tank (pretty low bioload) that hasn't changed for 2 years and his tank looks great.

Barbara
02-17-2008, 11:05 PM
How about this question...how do you know when you should change water?

There is a certain reefer who has a large tank (pretty low bioload) that hasn't changed for 2 years and his tank looks great.

I say either when it stinks (which has happened to me, but you have to have a fairly sensitive nose) or when you see your inhabitants acting poorly or poor growth. If you pay attention to your tank, I think you would notice when the quality is starting to drop off.

I have also heard that, the larger the tank, the less often you have to change the water. I'm finding that out with my poor little clown in the 10G tank. There is nothing else in there but that poor little fish, and I'm doing a 20% WC every 2 days just to keep the water from being cloudy and stinky. And I do have a filter on there, but not running carbon since I'm medicating. As I type this I realize I need to put the carbon in before I leave for CA 'cause the husband won't do water changes and won't know how to load the carbon.

Atlanta Aquarium
02-17-2008, 11:06 PM
Dang, with the size of the skimmer I just bought, I think I can get away with once a year then. Thanks Barbara, I'll make sure that the hair algae stays put.

Victor626nj
02-17-2008, 11:06 PM
i think that once you tank is established its kind of pointless im doing it cause i have been feeding heavy thesse past few day cause i got a purple tang that was a little picky and i wanted him to eat and now that he does its back to my normal feedings ...so just to help my skimmer out lol

Victor626nj
02-17-2008, 11:06 PM
rit if you start seeing a change of color in your corals its time for a water change

Atlanta Aquarium
02-17-2008, 11:15 PM
Victor it maybe too late when I starting to see the change in color of my corals. LOL That was happened to my recent tank crashed.

Victor626nj
02-17-2008, 11:16 PM
how are you recovering from that rit well better said how is the tank recovering

glxtrix
02-17-2008, 11:18 PM
I generally do 20g's on my tank weekly. I have roughly 170g of water. I believe in the less more frequent wc's. This topic is a good one. I know people who do 30% weekly and I also know people who don't change water for a long time. I over feed the hell out of my tank, so with the addition on my skimmer little wc's seems good for me.

tyleratl
02-17-2008, 11:22 PM
This is something I was wondering about also. I have decided to do 10% once per week. But, is that really needed or is it too much?

Atlanta Aquarium
02-17-2008, 11:26 PM
Well I was able to save about all of the nice SPS. That because Shaw took all the SPS to his place. I did lose some nice size colonies though. I prabably could have saved all the losses had I not been so busy that week. BTW, LPS and zoas weren't as affected by the ammonia spike as the SPS.

Atlanta Aquarium
02-17-2008, 11:29 PM
I always do a nice weekly water change. I want to do less frequent water change since I feel quilty of using too much water. I hope the new skimmer will let me do that.

Barbara
02-17-2008, 11:42 PM
Couple of folks made a good point about the feedings. I am a skimpy feeder. I only feed my fish every other day to every 3 days. Also, I do give the foxface and blue tang a reasonable sized seaweed to munch on every other day, but they eat the whole thing within 24 hours, so they go another 24 hours before getting another. Also, in my 90, I only have 5 fish.

Bioload probably plays a big part in how often WC is due. I tend to agree with those folks who bring that up, and I shouldn't have been so cavalier in my answer given I probably run a lighter load and less feedings than most.

saltwater junky
02-18-2008, 12:04 AM
wow i feed my fish 4 time a day,and i do 20% water change every week and still pull out a 5 gallon bucket of waste a week

FutureInterest
02-18-2008, 12:53 AM
A lot of people have to change their water every week to keep their nitrates down. Many other people don't have this problem so they can get away without doing water changes for extended periods.

I fortunately fall in the latter category. As such, I tend to do water changes every 2-3 months. I don't recommend going longer than 3 months... as certain necessary trace elements that we do not regularly dose do get used up over time. In my tank, I start seeing tip bleaching and other negative aspects at around the 3 month range although all parameters were normal.

I once did go 7 months without a water change. My macroalgae though went asexual so I had to then do a massive change. :(

Ralph ATL
02-18-2008, 5:49 AM
you should do about a 0% water change at least once a month. This will insure that trace elements are maintained & ions remain balanced.

ericmcj31
02-18-2008, 6:40 AM
How about this question...how do you know when you should change water?

There is a certain reefer who has a large tank (pretty low bioload) that hasn't changed for 2 years and his tank looks great.


I think I know who that is-and it does look great

SShindell
02-18-2008, 6:46 AM
shhhhhhhhhh..............

I would not recommend this at home.....:)

The tank in the office gets a 10% change every two weeks.

Gwhiz
02-18-2008, 8:22 AM
I change about 10% every other week...

coblerx4
02-18-2008, 8:33 AM
I was doing 10gals every 2 weeks on my 90gal. 6 months ago I switched to every 2 months with the ten gals and my tank is doing better now! I only feed every other day.

dough
02-18-2008, 8:48 AM
Every 7 to 14 days or when I remember.

Corigan
02-18-2008, 8:49 AM
I change about 10% a month. Seems to do fine by me, but it's not clockwork.

Matt

NavyReefer
02-18-2008, 9:02 AM
I only feed my fish every 4-5 days.....Someone needs to call the Humane Society on me!

gpenley
02-18-2008, 10:50 PM
I have three tanks and do a 20-35% water chamge at least monthly and prefarably every two to three weeks in each tank. NItrate level is good indicator. IF nitrates go up above 20 I do it earlier.

Victor626nj
02-18-2008, 10:56 PM
NItrate level.
whats that i have never been able to read nitrates not even when i put my lr in .......but i have read phosphates before i dont anymore but i know they are they cause of the hair algea thats growning in my overflow

Jgoal55
02-18-2008, 11:56 PM
Because I hate testing my water almost as I much as I hate changing my water I try to keep up with my water changes. Like others have said, its not just about the cleanliness and all that other stuff, its also about the trace elements.

My tank is not crazy SPS dominant but I do have a few that suck up calcium and if I go about two months w/o a change I can tell that they dont like it. I try to change once a month to keep it clean and I dose reef complete once a week in between.....so far seems to work great.

tnyga
02-19-2008, 6:54 AM
Two months? I think I overdone the water changes. I'm going to try to do less frequent water changes.

Try to remember, the only reaon Victor hasnt changed it more often is the fish he's constantly buying need to get used to the water thats in it...hence..new fish, old water :)

DannyBradley
02-19-2008, 7:07 AM
Typically 20% every two weeks, but it will vary from 10%-40% depending on the tank.

I don't believe in the multiple small changes opposed to one average change. It gives you really bad dilution ratios. If you do a small water change every day you're just re diluting the water you added back in the day before. If you remove 30% and add in 30% you're diluting the NO3- by ~46% because you're physically removing 30% of the NO3- and diluting the remaining 70%. That's significanty more effecting because of the 30% physical removal, and if done properly poses no threat to the animals in the tank.

Someone check my math on that.

Atlanta Aquarium
02-19-2008, 7:57 AM
Hmmm... Danny and Jin brought up good points. Dilution ratio and trace elements. It make sense to make a large water change but with less frequency. I definitely think I can go 3-4 weeks between water changes now that I have a much larger skimmer. I'm not so sure if I can go 2-3 months between water changes since my tank is heavily stock with corals, fish and heavily fed.

Stroid
02-19-2008, 9:17 AM
I think salinity is the biggest concern. I dont do nearly as many water changes as I should and ive noticed my salinity takes the biggest hit. I am doing 7g tonight to try to raise my Salinity. I swear we all spend so much time and money on this but seem to only do WC when something goes wrong. I am so guilty of that.

Cameron
02-19-2008, 9:23 AM
Rit, first I say keep doing what you were doing unless that is a problem. You were getting great results with your last method some of the best I have seen. If you decide to cut back, I get 30g (give or take) done every 2 weeks in my 125g and that seems to be working very well. I tried to go without water changes, but found at 3 months things weren't looking or growing as well and at 5 months my tank had seriously gone downhill. Water changes seem to help stabilize the water column IMO. There is just a lot of crap in the water that tends to build up I believe and no amount of skimming or other filtering is going to get it as effectively as a water change.

Atlanta Aquarium
02-19-2008, 9:51 AM
No, I don't have any problem with my last setup. Actually, I had very good result with growth and coloration of the all my corals. I agree with you that it's the frequent water changes that I made that yield me good result. At the same time, I don't want to overdo with the water changes since water seem to be precious commodity these days.
The new skimmer that I got seem to do a really good job so I figured I might want to cut back on my water change just a bit. I won't cut back to 2 months though. I think that's too long between water changes.

Skriz
02-19-2008, 10:06 AM
you should do about a 0% water change at least once a month. This will insure that trace elements are maintained & ions remain balanced.


This will ensure that nothing is maintained!!! ;)

DrNecropolis
02-19-2008, 11:40 AM
I change out about 20 gallons once a month, everything seems happy and growing to me

Patrick214
02-20-2008, 2:09 AM
Typically 20% every two weeks, but it will vary from 10%-40% depending on the tank.

I don't believe in the multiple small changes opposed to one average change. It gives you really bad dilution ratios. If you do a small water change every day you're just re diluting the water you added back in the day before. If you remove 30% and add in 30% you're diluting the NO3- by ~46% because you're physically removing 30% of the NO3- and diluting the remaining 70%. That's significanty more effecting because of the 30% physical removal, and if done properly poses no threat to the animals in the tank.

Someone check my math on that.

A 30% change from a given volume of water will remove exactly 30% of nitrates, assuming new waters NO3 is zero. Whereas smaller continuous water changes will remove less than 30% because of dillution.

A 30% water change in a tank containing 10ppm of nitrate will reduce nitrate to 7ppm. i.e. 10ppm*.7 + (.3*0ppm)= 7ppm

for instance if we replaced the water change water with water of 10ppm nitrate it would yield 10ppm overall after the change
10ppm*.7+(.3*10ppm)= 10ppm

If however we did three 10% percent changes on a tank with 10ppm nitrate it would remove

10ppm*.9 + (.1*0ppm) = 9ppm
9ppm*.9 + (.1*0ppm) = 8.1ppm
8.1ppm*.9 + (.1 *0ppm) = 7.29ppm.....10ppm-7.29ppm= 2.71ppm removed

27.1% export vs 30% export

So one thirty percent change removes 3ppm nitrate vs 2.71ppm nitrate via three 10% changes, thats only a 10% increase in nutrient export add in that the larger water changes will also increase the volatility of the waters chemistry given that any change occuring chemically from the water change will be magnified three fold occuring all at once as opposed to spreading out the changes over three different ocassions. Even if the major ions are in line Ca, Alk, Mg there can be differences in chloride ratios and other things we dont test for that are magnified by bigger water changes. I am actually of the belief that smaller more frequent water changes allow mature reef tanks to stabilize chemically alot better than large changes while still removing enough waste. The extra nutrient export from larger changes is pretty negligible and smaller WC's are easier anwyays. Generally the easier something is to do the more likely we are to do them. huge water changes atleast for me take forever compared to a quick 20 gallon change.

Barbara
02-20-2008, 8:20 AM
Interesting read Patrick.

Atlanta Aquarium
02-20-2008, 8:44 AM
Patrick, it's true if you only compararing 3 10% water changes with a 30% water change. The dilution is minimal. Over longer period of time such as 1 year worth of water changes, the dilution factor would be greater.
A 30% water change is not harsh at all to a system if the system is stable. I noticed a difference in growth with 10% water change vs. 30% water change. I see better growth and response from the corals with a 30% water change. Of course, this method was done with observation. There are flaws in that. A more scientific approach must be done to truely back up my claim.

sagent3000
02-20-2008, 9:37 AM
now you all have me feeling like an over achiever i do a 30% change weekly. i guess thats why my corals grow slowly too http://www.ez-smilies.com/smilies/sign0013.gif to all my corals.

i think i am going to try doing a water change every 2 -3 months and see what i get

Jgoal55
02-20-2008, 10:27 AM
A 30% change from a given volume of water will remove exactly 30% of nitrates, assuming new waters NO3 is zero. Whereas smaller continuous water changes will remove less than 30% because of dillution.

A 30% water change in a tank containing 10ppm of nitrate will reduce nitrate to 7ppm. i.e. 10ppm*.7 + (.3*0ppm)= 7ppm

for instance if we replaced the water change water with water of 10ppm nitrate it would yield 10ppm overall after the change
10ppm*.7+(.3*10ppm)= 10ppm

If however we did three 10% percent changes on a tank with 10ppm nitrate it would remove

10ppm*.9 + (.1*0ppm) = 9ppm
9ppm*.9 + (.1*0ppm) = 8.1ppm
8.1ppm*.9 + (.1 *0ppm) = 7.29ppm.....10ppm-7.29ppm= 2.71ppm removed

27.1% export vs 30% export

So one thirty percent change removes 3ppm nitrate vs 2.71ppm nitrate via three 10% changes, thats only a 10% increase in nutrient export add in that the larger water changes will also increase the volatility of the waters chemistry given that any change occuring chemically from the water change will be magnified three fold occuring all at once as opposed to spreading out the changes over three different ocassions. Even if the major ions are in line Ca, Alk, Mg there can be differences in chloride ratios and other things we dont test for that are magnified by bigger water changes. I am actually of the belief that smaller more frequent water changes allow mature reef tanks to stabilize chemically alot better than large changes while still removing enough waste. The extra nutrient export from larger changes is pretty negligible and smaller WC's are easier anwyays. Generally the easier something is to do the more likely we are to do them. huge water changes atleast for me take forever compared to a quick 20 gallon change.

my head hurts....

either way patrick thanks for that...its an interesting way of looking at it.....

here is a question a little bit off topic....if you have a salt container of 40 gallons....you use 20, then refill with RO/DI does that make the next 20 you use worse?
Is this not as good as say using all 40 in two consecutive Wc's?

Patrick214
02-20-2008, 11:44 AM
lol only an accountant could produce that answer.

Reef, if you extend those numbers out over a greater period of time there would be slightly more dillution but alot less than you would think. The math is kind of annoying but it doesnt actually remove alot more if you follow it through. I am not saying do not do 30% changes, i was just saying that i would prefer three 10% changes to one 30% change any day if all other things were equal or even two 25% changes as opposed to a 50%. Unless of course you need to export something quickly. I'm sure your tank appreciated the larger water changes but its important if you do smaller water changes to do them more frequently to make sure you give them a fair chance. anyways our tanks are the best indicators of what it needs, personally i do 10% weekly change and every once in a while i do a slightly larger one.

Cameron
02-21-2008, 2:22 PM
20% every two weeks has done wonders for my tanks. I can't imagine doing more would help much.

DannyBradley
02-21-2008, 9:38 PM
A 30% change from a given volume of water will remove exactly 30% of nitrates, assuming new waters NO3 is zero. Whereas smaller continuous water changes will remove less than 30% because of dillution.

A 30% water change in a tank containing 10ppm of nitrate will reduce nitrate to 7ppm. i.e. 10ppm*.7 + (.3*0ppm)= 7ppm

for instance if we replaced the water change water with water of 10ppm nitrate it would yield 10ppm overall after the change
10ppm*.7+(.3*10ppm)= 10ppm

If however we did three 10% percent changes on a tank with 10ppm nitrate it would remove

10ppm*.9 + (.1*0ppm) = 9ppm
9ppm*.9 + (.1*0ppm) = 8.1ppm
8.1ppm*.9 + (.1 *0ppm) = 7.29ppm.....10ppm-7.29ppm= 2.71ppm removed

27.1% export vs 30% export



I think you're incorrect with your approach. I thought the exact same way for years. If you take 10 gallons of water and add 30% to it, you will dilute the NO3 by 30%.

If you take 10 gallons of water and remove 30% you're left with 70%. You then dilute 70% of the remaining NO3 by the original 30%. That yields a larger dilution. If my math was correct, it would be 46%.

Patrick214
02-21-2008, 9:55 PM
I think you're incorrect with your approach. I thought the exact same way for years. If you take 10 gallons of water and add 30% to it, you will dilute the NO3 by 30%.

If you take 10 gallons of water and remove 30% you're left with 70%. You then dilute 70% of the remaining NO3 by the original 30%. That yields a larger dilution. If my math was correct, it would be 46%.

If i remove 30% of the water with 10ppm nitrate without adding anything, there will still be 10ppm nitrate in the smaller body of water. That remaining 70% of original water still in the tank will still contain 10ppm nitrate. Then i add 30% new water with zero N03 resulting in a thirty percent deduction. hence the formula i used: (10ppm*.7) + (0ppm*.3)=new nitrate.

DannyBradley
02-21-2008, 10:06 PM
Ahh... I see where I made my mistake. I subtracted my NO3 twice. I stand corrected.

Patrick214
02-21-2008, 10:12 PM
Yea, I think you were thinking you remove 30% of the nitrates then dillute it again, but when you remove 30% of the nitrates you are also removing 30% of the water as well so there will still be the same nitrates till new water is added.