Water changes

[robert1305]

I posted this on another forum, it had 40+ views and not one reply, so as a member of this forum I post my view and leave it open to comments.

I know that there are members who religiously carry out water changes every Sunday, or whenever, and use all the prescribed additives, what I would like to know is it absolutely necessary, I cast my mind back to when I set my first tropical tank up, approx 62 years ago!! and I can honestly say I do not remember doing regular water changes in those days, and we certainly did not have the additives and medications that are available today, I can only assume that the tank was kept in good condition by good filtration, a theory that I still hold today!!
Three weeks ago I did a 25% water change, I took all the relevant readings, and today I took the readings again, and the only difference is a very slight nitrate reading,
The tank is looking great, the fish look happy and healthy, and the bladder snails are enjoying them selves keeping the tank clean, the only thing I have done in 3 weeks is occasionally added some Seachem Prime, I am not saying that water changes aren’t necessary parse, its just the  regularity of them I question

I just wonder who is the main advocates of the weekly water changes, I site my own experience every time I visited a certain aquatic establishment with a water sample I was told that it had anomalies, although the api test kit they sold me at a cost said everything was OK, and there advice was was that I did a 30% water change every other day and treat it with a load of additives that they suggested I purchase from them at a price, which to give them the benefit of the doubt I did and at the end of the treatment my API readings were exactly the same!!!!!!!
I am now entering the fourth week and my tank is doing FINE


Regards Bob

PS.... I graduated to a 5ft marine tank and to set that up I had to do a round trip of 160miles to collect sea water from a cove at Whitby!!!!!!

[fr499y]

my nano is open topped and i sometimes forget to do a water change, but i do top up every few days, Sometimes i go 2 or 3 weeks without a water change. I have ran tanks with one water change a month ( with top up in between! ) and not had any problems. Stocking levels can play a massive part in the balance as well as the type of filtration you run. I Wouldn't recommend it, stick to weekly water changes, even 10% helps.

[Baddams]

I remember that my dad never did water changes back in the '70s when he had a Heinz 57 community tank with undergravel filtration. Just topped up with tap water that had been left overnight.

I don't remember him having particular problems with mortality, but the tank was always (by our standards today) filthy.

[Ric]

When I was a teenager and had a 100ltr tank, I only changed the water when it started to look brown, i.e. every 4-6 weeks. We had our own well so no de-chlorinator needed.

The tank started out with an internal filter, later changed to an external. had a hotchpotch mix of angel fish, live bearers, neons, kribs, corys and even a common pleco. Everything was thriving / breeding / spawning.

My only problem was high nitrates which came with our tap water as we were living in a rural agricultural area, so that was a result of fertilizers being used on the fields. (Later on my parents had to be connected to the water supply system as the nitrate levels were deemed exceedingly high and posed a health risk, especially to babies).

Nowadays I stick to about 10% water changes per week, as advised by great local fish shop owner many years ago. 
Only exception is when I had to use medication, like recently, in order to get rid of any residues, then I will change up to 50%.

[Vale!]

 ... not one reply ...

Not, strictly-speaking, true! 

Welcome to a forum that's not moribund!

The test kits that we use measure, to a greater or lesser extent of accuracy, some of the parameters of water chemistry that have some degree of impact on the mini ecosystems in our aquariums. But by no means all. 

One of the more significant 'missing' parameters is "redox" ( a portmanteau of 'reduction' and 'oxidation'). Much of the biological activity that happens in an aquarium depends upon the ability of the system as a whole to facilitate the swapping around of electrons and protons between chemical compounds and across biological membranes. A system needs to be able to allow both oxidation and reduction to happen simultaneously, as required. Without intervention, a system tends towards (and can become, in extremis) a strongly-reductive or a strongly- oxidative environment. In either case, this will have a negative effect on the overall efficiency of a biological system.  Consequent effects on organisms may not be immediately apparent but 'bad' redox inevitably causes stress at some level. Regular water-changes help to maintain a favourable redox balance.

Still thinking 'electrically', the benefits given by the minerals that our aquarium water carries, and which are essential for our fish etc., don't last forever. That is to say : even though we may measure a certain value for (say) General Hardness long after our last water-change, that doesn't necessarily mean to say that the GH is still as useful as it once was. Its minerals' ability to give up or to accept electrons will certainly have decreased and, depending upon variables, may have ceased altogether. A water-change makes sure that the system is 'recharged' in this respect. Same goes for many other inorganic compounds in the water, all contributing to its 'ionic strength'.

A water-change can restore dissolved oxygen concentration where a system is under relevant stress. Ditto bicarbonate/carbonate concentration where a system is becoming buffer-deficient and unwanted acidity is threatening to increase. 

More broadly, a water-change dilutes a number of substances and reduces the number of perhaps less desirable organisms in an aquarium's water-column. A by-no-means-exhaustive list may include: ammoniacs (ammonia, nitrite, nitrate) ; hormones excreted by fish ; toxins, ditto ; viruses ; fungal spores ; heterotrophic bacteria ; parasites and other pathogens ; and suspended algae.

There are systems, usually of rather extreme character, to which not all of the above may necessarily apply ; in terms of 'normal' aquariums, though, these would be some of the reasons I would put forward in support of regular water-changes. When they're accompanied by other forms of maintenance (substrate-hoovering and/or filter media-rinsing, say) their beneficial effects can be amplified.

I rest my case, M'Lud !


[Edit : to acknowledge interposed posts]

[Cheltgirl]

Water changes aren’t just about keeping the tank clean. I would have tried (and failed miserably) to explain it as Vale! has but thank goodness he got here first. I agree with him completely.

[Annie]

Sorry to jump in with another question, but does follow on @"Vale!" comments

If you don’t do water changes, are you reducing the oxygen available in the tank and therefore affecting the health of your fish ?

We left one of our tanks for 2 weeks, done w/c today and fish acted strange going to water level as if getting air, only did for about 15 mins but my Corys are still doing it....have I been a bad mommy eek !

[Cheltgirl]

Only if you didn’t have sufficient gas exchange at the surface or via diffused bubbles.

Another reason I believe regular changes are good is if you left your tank for a few months then the parameters would be fairly different to your supply water after that amount of time (see Vale!’s post) so if you then did a change or needed to in an emergency then you’ll be adding in much different water than what the fish had become accustomed to potentially causing more problems. The last thing you want in say a sudden ammonia spike is not to be able to change much water for worry of shocking the inhabitants.

[Gingerlove05]

Oxidisation and reduction relate a bit differently than oxygenation
Oxidising is a mineral (eg calcium) taking on the oxygen electron (part of an atom) so instead of being just calcium mineral on its own with just its own electrons, it takes the oxygen’s electron(s) to it becomes calcium-oxide, the reduction is the oxygen losing its electron(s)
You will have seen oxidisation on any old bit of steel thats rusted (rust is iron oxide) or old church roofs (the now green copper ones) or on old copper central heating pipes, instead of the copper colour you get the green patches. This is copper oxide, the result of copper reacting with air (oxygen)
Oxygenation relates to the amount of dissolved oxygen (in our case ) in the water
Hope that makes some sense...

[stuaz]

I do weekly 50% water changes on all my tanks (Unless I am away on holiday/ away for work). The fact that when I am away and the water doesn't get changed the tank doesn't implode into a mess of dead fish would suggest the water change is not strictly needed BUT there are so many other factors at play. Tank Size, Filteration, Stocking, Planted, etc etc etc.

I do not add anything to the water (aside from dechlorinater).

I actually do enjoy doing water changes. I find the process of cleaning the tanks calming and gives me a chance to interact with the tank in a similar way to how feeding does.

Am I hurting my tanks for doing 50% weekly water changes? Unlikely based on my experiences. I believe fresh, clean water is a great thing for fish in our closed ecosystems.