water changes... really? are they necessary? debate - Page 3 - Tropical Fish Keeping - Aquarium fish care and resources
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post #21 of 27 Old 03-08-2011, 10:54 PM
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Originally Posted by rnsheehan21 View Post
i have to say that many of your posts have been very interesting with the different angles you guys have come at this topic with. I would agree with many of your points and disagree as well but its good to hear your knowledge, thoughts, and ideas on the matter. to ME these is just a matter of your tanks biology. A fish tank being an enclosed ecosystem should, as in nature, be balanced. This is a goal all of us as aquatic keepers have in common.
...i find its unfortunate that there is not enough information on the internet (that i found) that can support this issue one way or the other. if you find some ( thats not a sales pitch for a product) please share!
Plenty of information out there on benefit's of water changes and effect's on fishes as well as the result's of few water changes. Keep learning,searching.
You will struggle, to achieve nature's balance in a glass box of water where there are no tides,current's,rains,to take pollution away and where fish cannot swim away to escape it.
Best one can do is to learn to take care of the water in a closed system. Fish keeping becomes easy after that.

The most important medication in your fish medicine cabinet is.. Clean water.
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post #22 of 27 Old 03-09-2011, 04:10 AM
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Originally Posted by thinkrevolutionx View Post
Water changes mandatory in a planted tank? No.

Helpful? Yes. I'm no scientist - so I can't pretend to know what's going on at the microscopic level - however I will say this.

One of my tanks is an understocked 29 gallon with 2x hob filter and lots of live plants. Post cycle the tank never had anything above 0.0 ammonia nitrate or nitrite, and the PH has stayed the same.

So, the tank is nice and healthy, the fish look good. However, you ever see that film that kind of gathers on the top? Similar to what gathers on puddles? Well, that's not good for the fish, and it's not something you can measure - and it lends itself to the fact that many, many other things are going on in the tank that we aren't aware of.

That being said, it's obvious clean, fresh water is great for fish - but is it necessary? No, I don't think so.

Helpful? Sure.

Myself, I don't really believe in water changes on a scheduled basis. What I do is every week or two i'll stir up the substrate and suck whatever pops up, and ill get rid of the film on the top. That process is usually good for dumping a bunch of water out, which I will then replace with fresh water. Boom, water change - but not for the sake of changing the water.

Also, the whole "discus need daily 100% water changes or they will die" thing is just so, so silly. Yes i'm being sarcastic there but really, discus are fish. If the tank is healthy and clean, surprise - they will function just like other fish. I get that they are expensive and people stress, but cmon.
No, regular freshwater to the aquarium along with removing old water is not necessary (as you state above) if you don't mind sickly fish.
Discus you brought up, (not me) are not particularly difficult to care for so long as their needs are met but they do have specific needs.Water changes with Discus are determined by number's of fishes being kept,foods offered,size of fish, adult's/ Juveniles,, and ones expectations with regards to health and appearance.If you don't mind stunted ,sickly,misshaped fish, then that's fine,perform fewer water changes.
Young Discus require large amount of protein rich foods to achieve growth potential which are best offered three or four times a day, as opposed to large single feeding. It is these feedings, and waste produced as a result ,that necessitate the often large daily water changes that folks who care for these fish or raise them for their livlihoods ,perform.
The Discus have high metabolisim's due to warmer water (also a necessity) and foods are quickly digested and pass through the intestines and ultimately into the water. If you want large healthy fish,, frequent water changes are not an option , they are a necessity for this species to remove waste from the fishes enviornment. I would submit that this also applies to all fishes.
It's all about your expectations.

The most important medication in your fish medicine cabinet is.. Clean water.
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post #23 of 27 Old 03-09-2011, 12:37 PM
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Very well put 1077.

Kindest Regards,

Keeping fish its not a hobby it is a passion!

I have a 55 gallon, 40 gallon, 29 gallon, 20 gallon tank, 5 gallon , and a 2.5 gallon all with real plants.
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post #24 of 27 Old 03-09-2011, 05:00 PM
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Mikaila and 1077 have presented good solid facts, and I fully concur with what they've said. I'm just going to take this in a slightly different direction that I hope will further illustrate their points and make it clear that water changes are always beneficial, though the extent (volume and frequency) may be variable depending upon your view.

Fish are the only "pets" we keep in a basically closed system. Dogs, cats, rodents, birds, amphibians (except fully aquatic like Mikaila's fascinating caecilians), reptiles--all these live in air and there is plenty of air moving around all of us. Not so with fish. They depend upon water; and as someone mentioned, we don't keep ourselves in a closed system, nor do we keep these other creatures in closed systems--so why would we expect fish to manage in a closed system? Of course, they won't, and they can't. Mikaila and 1077 have expressed why clear enough.

Our fish come from nature; some are wild caught, some are tank-raised, but their physiological needs are not going to change just because they were bred and raised in an aquarium rather than a stream in Amazonia or wherever. In nature, fish never live in the same water for more than a second. Water is constantly moving past them, or they are moving through water. And the ratio of fish to water volume exceeds by hundreds and thousands anything we could ever provide in an indoor aquarium. If the fish wants to escape something in the water, they swim elsewhere; that option is not available in an aquarium.

Nitrates are often mentioned as a measurement for water changes. But no fish in nature lives in water with nitrates anywhere close to what we often assume is "safe." I have data for streams in Amazonia where nitrate is so low it is undetectable. A nitrate of even 20ppm may have consequences for this fish long-term.

Fish produce solid waste which gets broken down by bacteria; it is not removed by filters, it remains in the water. Fish produce urine, some a great deal; this stays in the tank, filters do not remove it. Live plants will to some extent handle both of these, provided the fish/plant/water ratio is in balance, which means the fish load is very low. Fish also produce chemicals (as do some plants), called pheromones with fish, allelopathy is the plant equivalent. Filters do not remove these. Only changing the water can. In nature, water changes occur from rain and snow melt.

There is no detrimental effect from a water change. If significant water parameter differences are really an issue, there are ways to deal with that. Having to make the effort to provide what the fish expect to be healthier--and happier--is not something that is optional, or it shouldn't be. If one is going to undertake the keeping of a living creature as a "pet" then one should and must be willing to provide the necessities. Nothing else is defensible.

The extent to which water changes are required depends upon the species and number of fish, the presence of live plants, and the tank volume. Mixing certain species will necessitate larger water changes. Having live plants and a moderate fish load can reduce the volume and frequency of water changes. The reaction of fish to a water change speaks volumes; no one can seriously doubt the benefits.

Earlier one asked for data. In the November and December 2009 issues of TFH there was a 2-part article on water changes that was very educational.


Byron Hosking, BMus, MA
Vancouver, BC, Canada

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian. [unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]
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rnsheehan21 (03-09-2011)
post #25 of 27 Old 04-13-2011, 06:16 PM
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Hypothetically speaking

hey im new, first post..on any aquarium forum..
im not new with tanks however, and i rarely ever do water changes, and they have always been irregular.
that being said, say you have a 10 gallon tank with a crappy top fin 10 filter at 80 GPH, in a slightly overstocked, densely and diversely planted tank, and then have that water pumped up to a aquaponic grow bed that grows a pretty fair number of plants.. Do yall think thats adequate biological and plant filtration? no im not going into specifics, no time for now.

oh and i have a 55g,10g,and 3 gallon and the only one i feel i need to do water changes on is the 3 gallon, they are all well planted. and with sand substrate (cept 3 gal)

oh and putting willow branches in your tank does solve green water, as well as starve your plants if left in too long. IMO if nutes are your reason for water changes then willow could be a viable alternative
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post #26 of 27 Old 04-13-2011, 07:13 PM
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Currently I maintain a 25 tank system with a few other display tanks around the house. For all of the display tanks and many of the other tanks I would qualify as moderately to highly planted (there is still room to swim) I Do changes on them weekly in almost all cases. Now when I first started I only cleaned the tanks once a month and everything was healthy. Now that I have started changing the water once a week my fish are not only happy but happily breeding. I have had 8 separate species spawn in the last week alot of them were triggered but the water change. Basically what I am saying is that it all depends on what you want out of your fish keeping experience.

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post #27 of 27 Old 04-13-2011, 07:26 PM
The answer to this question is as simple as looking at nature...the nature, if we're smart, that we try to imitate in aquariums. The streams, rivers, ponds, lakes and oceans receive a constant supply of fresh rain water. This is especially evident in the tropics where it often rains every day.
To think that having a few plants in a tank with fish somehow eliminates the requirement for an on-going supply of fresh water is just not logical.
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