What Is *in* Water That Makes Water Changes Necessary?

[Maehlice]

The title says it all.

I've read countless times about water changes not being recommended but required. In general, my title question aims to answer "why" exactly this is so.

With proper feeding and particular planting & stocking , an aquarium's nitrate, nitrite & ammonia levels can remain low indefinitely. (This is the case with my 29 gallon aquarium right now.)

So if not for water quality, why do we do frequent water changes? What in fresh water is so vital to the aquarium's environment that weekly 20% water changes are required?

If it's just a matter of minerals and nutrients, is there a supplement that can be added instead?

If possible, I'd like to minimize (not eliminate) my water changes. I find it preferable to add a weekly nutrient supplement and then do water changes only once a month or so.

(I'm considering graduating to a 200 gallon tank late next year. Doing a 40-50 gallon water change every week seems a bit daunting.)

 

[DrRob]

Generally a mess of organics amongst other stuff. Oils from your arm. Scents and pollutants from your house. Many things really.

 

[mrvillicus]

good question that i also would like to know the answer of. Personally I believe it is used for maintenance just to ensure that nitrate is kept to a minimum and the fish have a fresh burst of clean water. Apart from that, like you say im really not too sure why exactly it is needed, someone please enlighten us.....

 

[phoenixgsd]

water changes ARE recomended AND required as part of basic maintenence, not sure where your info is from but ammonia spikes can happen at any time and need to be dealt with, water changes are made easier with a pump

 

[CezzaXV]

Also, fish hormones and all sorts of things we can't test for.

 

[Maehlice]

water changes ARE recomended AND required as part of basic maintenence, not sure where your info is from but ammonia spikes can happen at any time and need to be dealt with

This supplement and less-frequent water changes idea certainly won't preclude or obviate weekly water tests and periodic water changes if/when things go awry.

I've been lucky enough my ammonia levels have never spiked into lethal ranges. The few ammonia spikes I've had so far weren't lethal and self-regulated themselves (I presume through the same cycling process a new tank goes through ... like a "mini cycling", I guess).

water changes are made easier with a pump

It's not so much getting the water in and out but in obtaining the necessary quantity of RO I find daunting. The affordable, non-commercial [under-sink] RO systems typically have 3 gallon tanks. The largest expansion tanks I've seen are only 14 gallons. Obtaining and housing 40 gallons of RO isn't particularly something I want to do, if it's at all avoidable.

 

[Aquamaniac]

See that glass box you like to watch?
We put fish in it. And for them that box is home.
And like us humans they make a mess out of their home. They eat,drink,p*** and s*** in it.
But unlike us they can't flush the toilet or throw the rubish away.
Thats were you and the water changes come in.
All the organic mater will decay and turn into ammonia. Wich for the fish is poisonous.Even with a cycled tank the build up will eventually decay the water quality.Water changes help stabilize the system. We remove a percentage of this build up by removing old water and adding new water. That basically the purpose of water changes to help keep your tank stable and habitable for your fish. Because everything that goes in your tank stays in your tank.

 

[Baccus]

The other reason for replacing water in aquariums is that all living things with in that tank are using up mirco nutrients for healthy growth and development. And the easiest way to bring more of these nutrients back is by doing water changes. Since we have an enclosed system and its not subject to the natural ebb and flow of creeks, rivers even lakes which will change depending on the season and weather conditons.

 

[Mikey1]

See that glass box you like to watch?
We put fish in it. And for them that box is home.
And like us humans they make a mess out of their home. They eat,drink,p*** and s*** in it.
But unlike us they can't flush the toilet or throw the rubish away.
Thats were you and the water changes come in.
All the organic mater will decay and turn into ammonia. Wich for the fish is poisonous.Even with a cycled tank the build up will eventually decay the water quality.Water changes help stabilize the system. We remove a percentage of this build up by removing old water and adding new water. That basically the purpose of water changes to help keep your tank stable and habitable for your fish. Because everything that goes in your tank stays in your tank.

very well said.....

fish are basically living in their own toilet.....

so think about living in a pool with 10 other people, and your all doing "your business" in there.....would you like to have some of the water changed after a week? or would you prefer to have all of the "waste" just keep building up around you?

 

[phoenixgsd]

It's not so much getting the water in and out but in obtaining the necessary quantity of RO I find daunting. The affordable, non-commercial [under-sink] RO systems typically have 3 gallon tanks. The largest expansion tanks I've seen are only 14 gallons. Obtaining and housing 40 gallons of RO isn't particularly something I want to do, if it's at all avoidable.

can i ask why your using RO is there something wrong with the water where you are?

 

[Maehlice]

can i ask why your using RO is there something wrong with the water where you are?

Certainly. I live in central Indiana. My tap water's hardness is off the charts.

EDIT: I guess that doesn't really clarify much, though, does it.

It's been a while since I tested the tap water, but I remember it being in the 300's, or a GH of 20-ish, I think.

As referenced at http/www.tropicalfishkeeping.com/profiles/, most of the fish and plants I keep now or want to keep in the planned larger aquarium prefer <12 dGH.

 

[snazy]

As already mentioned, nitrAte is one of the things but certainly not the only reason why to change some water.
There's a lot of acidifying process going on in a tank, for example ammonia to nitrIte conversion. If the tank is left with no tap water changes, the buffering capacity of the water will diminish with time, how long depends on one's water, but if no water changes are done, you'll get a sudden ph crash, then the beneficial bacteria will die, then ammonia spike and a very hard process to get it back without killing all fish.
Another reason, as mentioned by someone else already is nutritients that tap water contains and that get depleted from tank water. There's no artificial additive that comes to my head and won't be dangerous to play with if dosed manually instead of water changes. I know people use RO water for shrimp and then add a package of nutritients produced specifically for them to the water and only do top ups then. But if you have a community fish tank, how are you gonna get it right for all species? I haven't heard of anything similar being produced for freshwater fish either.
Then you have to take into consideration all the rest of the stuff, organics and Total Dissolved Solids. There are fish that are very sensitive to that, like Discus for example, even clown loaches and generally most fish that come from super clean water. I have a TDS meter and although my nitrAtes are very very low due to the plants, the TDS rises of course and it would have skyrocketed to the point of no return if I didn't do weekly water changes. 50% brings it right back to about my tap water value.


As for ammonia spikes, I don't think that would be an issue with a well filtered tank. Everything produced by the fish goes through natural chemical processes and doesn't stay in the form of poop really. That's why you need a good filter/filtration. Some people keep tanks underfiltered(unknowingly), not enough flow either to pickup the fish left overs and debris from the bottom and even if they forget to clean something small like a melting plant they get an ammonia spike. I would advise, reseach, spend a few more quid on a second filter, don't overstock to the point of silliness and you'll never ever get an ammonia spike unless you use the dish washer to clean the sponges You'll barely need to siphon either if the tank is filtered well. If you are getting spikes without a genuine reason, like overwashing your filter, then you are either very underfiltered, heavily overstocked, feed a tin of food per day, or something of the sort.

 

[Maehlice]

@snazy - If this was GameFAQs or Yahoo! Answers, yours would be my "accepted answer".

The only way I know to reduce TDS is RO, so I'd have to constantly run the aquarium water through an RO filtration system. Plausible, but not particularly ideal.

KH is easy enough to manage, so I think I could prevent ammonia spikes and rapid pH shifts.

However, these elusive Micro-nutrients is where I find a great dilemma. I'm no marine biologist, so this layperson will have to stick with regular water changes.

Thanks to everybody for all of your input.

(If one day I befriend a biologist from SeaWorld or the Georgia Aquarium, maybe I'll revisit this idea. It sure seemed good at first, though. )