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Daharkazangel

Can you overdo waterchanges?

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Just a general question. Is there such thing as waterchanging too much water OR water changing to often? I know some people water change like 80-90% in one hit and there fish look sexy. I myself water change my oscar tank two-three tines a week and about 25-50% at a time, is this too much? Just want to see some opinions :)

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Alot of variables means there isn't a straight cut answer for this...

Need to consider feeding habits, filtration being used, stocking levels etc etc

This is what my q was based around.

Ok scenario 1: friends tank

125gal , has a canister, stock with clown loaches, rainbows and corys. Quite heavy stocked, feed lightly once a day. 80-90% w/c fortnightly.

Scenario 2: my tank (canister coming)

100gal, only has two internals for now, heavily stocked with oscars and a plec. Feed quite heavily to accomidate baby oscars twice a day. W/c two-three times per week, 25-50% per change.

Edited by Daharkazangel
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you need to check your nitrates. This is why most of us water change. (water volume, stocking, feeding amounts, type of fish and size of fish affect this)

As a general rule more than 50% at once is a risk.

I have done 80% in the past with no ill effects. But its all about limiting risk.

Fish generally dont like dramatic changes to their environment.

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If you are using the same water as in the tank.....the more changes the better

I commented on How good fish looked in a LFS.....the owner showed me the system and said it gets about an 8% water change every day

I've heard of a chap who raises Discus commercially....he does 90% water change 4 times a day!

Many shops in Asia don't have filtration....just air stones ...but they do regular large water changes

The More you can do the better....it does not harm....unless the the New water has a different chemistry/temp

There is no filtration system that is as Good as a water change....

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As a general rule more than 50% at once is a risk.

i'd disagree, plenty of discus breeders do 100% daily wc's, and my fighters always get 100% weekly wc's never had an issue with it

I've done plenty of big waterchanges with no losses,

you wanna know what the secret is to them? - getting the water thats going in as close to the water that is coming out of the tank.

so make sure the ph, hardness, temp are all close enough not to cause any undue stress on the fish during wc's.

Fish generally dont like dramatic changes to their environment

I agree with this, 9x outta 10 its the dramatic changes in water params that results in your fish dying after doing waterchanges.

personally i dont think you can over waterchange your tanks, if you match your water params up you shouldnt have any issues.

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I have a NPT tank that I do water changes on every 2-3 MONTHS. This tank is heavily stocked but the plants use the waste. I check ammonia, nitrate and nitrite.

My fighters get massive changes, up too 100% every 2 days but these are in small containers (growing out boys) and this is the norm for these fish.

I think the big thing is checking your water. Do a change if necessary. You can definitely change too much and/or to often.

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i would say doing such waterchanges is for only such extremes.

the only need to do this is

a. you powerfeed for growth ect

b. you are heavily stocked (lfs situation/ breeder)

c. or your fish require high quality water.

many discus breeders do this for fast growth, personally i would rather do two 40% water changes per week than a 80% a fortnight.

thats just me, the reason why is if you have a good biological filter media its fine.

the main idea behind not changing all of the water is this can rid of the benificial bacteria (nitrifying) which breaks down the fishes waste.

change to much and you will possibly get an amonia spike. but with a good biological medium you shall be fine.

personally i do two 25% water changes maximum per week. i usually do one 30% w/c per week, i change it with accordance to stocking

HTH

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jebus im slack. i do a 25% change on my 8ft display ever month or 2. and even then i ***** and moan about it. i top up the sump when it starts to get low but other than that i just leave it alone as my african are happy the way it is. every time i do a change they all start getting alittle frisky and fighting. so i just leave it be.

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There is some interesting mathematics I did one day when I was bored.

I wanted to consider the ramification of period between water changes. So I considered what would happen if a water change of 10% per day was made compared with 70% once a week. (Notice that the total ammount of water changed per week is exactly the same, only the timing of the changes differs)

I then considered that waste (or lets say poop) is a fixed number per day, so lets say 1 poop per day. The maximum amount of poops ever in the tank following the different regimes is in both cases 10. The differnece is when you do a weekly change the least ammount of poop ever in the week is 3, compared with 9 for a daily change.

So considering the highest concentration is the health issue, the key is the amount of water to change, not the when to change. I like this result is daily water changes are a pain.

Now considering the how much to change question, I agree with Kasman, monitor the nitrate. If you are strict with feed in and constant water change in a month you will have a pretty good idea where your nitrate is going to sit long term. If it is heading too high, increase the volume of water changed.

The big advantage of more regular smaller changes is you do not have to be as concerned with matching water parameters. As said once you get past about 25-30% you need to be careful that your water paramaters are not too different between the new and old water.

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thats what i figured when i decided to sump the 8 footer. i just did the research and loaded it full of media and put 2x 13,000lph return pumps. technically my tank cycles about 18 times and hour. my africans seem to like the raging torrent in the tank and it keeps it crystal clean.

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what would you suggest if the nitrate out of your tap is already high, my nitrates in the tank are always above recommended but doing more water changes doesnt change it cos it come out of the tap like that, my tap water is between 30-40ppm.

cheers

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So........

When I get my diy canister going I really dont need to w/c as often as I do BUT theres no harm in it?

My mates tank is heavily planted and dirted. The 90% wc fn seem to do wonders but imo it must stress the fish, even coming from tank water..

Good question about nitrates in tap water. Ive never tested my tap water, only for ph. Hmmm

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I used to change 100% up to 2x daily for discus juvies mainly because it knocks the bacterial load on the fry down, cutting down losses and the fish need to be packed in as tightly as possible to get best growth.

the tanks were best left filterless so as not to have any nitrite or nitrate. If there is no filter there is no nitrate, that simple. The ammonia obviously would climb but water was changed before it got to any point of harm. Obviously this isn't recommended for every tank, it's just the best way to get growth and cut losses, if the regime isn't stuck to religiously the fish will drop dead.

It really depends on fish habits, breeders time restraints etc.

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