# Are water changes necessary?



## Red_Rose (Mar 18, 2007)

I was thinking about this a week or so ago during a really bad headache so it may not make much sense.

Sometime this month, I had a headache so I was just lying down and watching my betta swim around in his tank. I started thinking about water changes(why I don't know) and what I would like to know is if they are really necessary if there's no problems with the tank?

Since it's cooled down here, I replace about half a liter of water a week. Sometimes it's a little longer. By the time six months arrives for a partial water change, I basically would've already done that from the water I've been replacing when it evaporates. Instead of it being one large change, it's just a gradual one. That being said, would a person really need to do a partial water change every six months if you're pretty much doing that over the course of the six month period?


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## cs_gardener (Apr 28, 2006)

The problem is you're not removing anything that may have built up in your tank over the 6 months, you're just replacing water. If you are adding tap water it may have minerals that are becoming more concentrated in the tank when the water (pure water, no other substances) evaporates. The water changes every 6 months or so help keep anything from concentrating to too great of levels. If you were siphoning out 1/2 a liter of water per week and then replacing it, that would be different because you'd be removing the minerals, chemicals, etc along with the water. So if you were actually doing a water change every week you wouldn't need to do a big change every six months, but you are only topping up the water and not removing any of the harmful substances that are accumulating so you do need to do the large 6 month water change. 

I just recently changed the water in 3 of my tanks (last change was Feb/March) and was surprised at how much the plants took off after the water change. In one tank, the water didn't look particularly stained by tannins and I couldn't figure out why it was looking so drab and dark, well the water change fixed it and it's now at least twice as bright and I can see what I have in there from across the room instead of my former limit of 3 ft away from before the water change.


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## newbie314 (Mar 2, 2007)

I replace the water too, but still did a 6month 50% change as recommended.
I believe it's too help the possible build up of chemical, etc that might be harmful (maybe even nitrates if the plants don't get to them).
The change did help reduce the tannins.

Replacing the evaporated water is not the same as taking water out and replacing it.


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## Mr Fishies (Apr 9, 2006)

Like Catherine said, I think what you need to worry about most is buildup of tapwater borne salts and minerals. This can happen to potted house plants owned by people with "rich" water.

I am not a water expert, but I do recall your posts about hard water (in the 20+ dh/kh range) and I'd suspect that even though some plants are going to use some of the minerals up, probably not as fast as you add them with water that hard.

Some folks more sagely water wise may also suggest that some elements will be used up faster than you're adding if you only top off evaporated water.

I have to use additives to get my water up past 2-3 deg kh/gh...I wish I could take a few degrees off your hands.

I do water changes when I thin plants and trim my stem plants - the lowered water surface is my "ruler".


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## Zapins (Jul 28, 2004)

Its best to do water changes once a week of 20-60%. 

6 months is far too long under most circumstances.


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## mistergreen (Mar 3, 2007)

I've heard/seen people not changing the water at all. They probably add a little GH (Ca & Mg) once in a while in addition to topping off evaporated water.

this guy said he hasn't changed the water in 2 years
http://www.plantedtank.net/forums/photo-album/50456-zero-water-change-20-75-a.html


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## Zapins (Jul 28, 2004)

Like I said before, under most circumstances 6 month water changes are not a good idea. 

If you are able to balance the inputs exactly with the outputs then it is possible to do no water changes, but knowing exactly what is entering and exiting the tank and being sure that no nutrients accumulate over time is a very tricky science, definitely not something most people can do, let alone a beginner. 

Many organic materials take months to decompose, so you would have to have an extremely low number of living creatures in the tank that would reduce the amount of organic material being put into the water. Feeding schedules would have to be near non existent because those nutrients would build up faster than bacteria could digest them into raw nutrients that the plants would tie up in their tissues (ultimately being removed by trimming). Not to mention a host of other variables you would need to consider. 

Overall, not changing water for 6 months will result in reduced health for all tank inhabitants.


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## Endler Guy (Aug 19, 2007)

I suppose that would depend on your water chemistry. If there's even a little salt in your water, it could build up over time. Thus, the recommended 6 month water change as a precaution. Plants will take up excesses of heavy metals but I don't think they do salt.

Topping off and fish food should be sufficient to replace lost minerals. Anything organic, including biological waste, hormones, allelochemicals, or other products of biology will be broken down in a timely enough manner. One of the theories that CO2 enriched tanks peter out so quickly is that the allelochemicals build up quicker than they can be broken down, and that is with the enormous amount of water changes that are required for such a setup.

RedRose, I just realized who you were. I forgot to thank you for the conversion formula for converting ppm to degrees. Thanks!


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## Endler Guy (Aug 19, 2007)

Zapins said:


> Its best to do water changes once a week of 20-60%.
> 
> 6 months is far too long under most circumstances.


It's nice to see everyones veiws. Admittedly, when I first discovered this forum, I'd have thought, "Doesn't he know he's in the El Natural sub-forum?" I thought it was about and for her methods. I've since learned that she's an invited host and that this forum is about natural planted tanks in general. There are no hard and fast definitions of "natural" or even "low-tech."

I used to wonder why she'd never say anything in certain threads. Now I realize that it must be pretty difficult to moderate a forum so general as this and try not to let your own knowledge and experience into the mix without sounding preachy.

BUT, I do think that Diana deserves at least a little respect. It'd be nice to know if you had at least read her book since many here are following her principals. You've made over a thousand posts. You must know what "El Natural" is and who hosts it and why she was invited to do so.

Yes you did qualify your statement with "under most circumstances" but you didn't specify what those circumstances were ESPECIALLY in THIS forum hosted by her! Many newbies will be reading that, whether they're here by chance or because they've read her book.


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## Zapins (Jul 28, 2004)

Wow, I didn't realize this was the el natural forum !! I was just answering posts from the new post tab. Thanks for calling it to my attention I had no idea (ugg i feel bad now)!

No disrespect to dianna or this forum intended, on the contrary I think I missread the context of the question (in relation to the forum its on). I read it thinking that a local fish shop guy had mentioned only needing to change the water every 6 months and it brought to mind countless horror stories from back when I worked in my old LFS of new people been given bad advice (3x day feeding + 6 mo water changes). Dianna has good reasons for 6 + mo of no water changes.

As a note aside: I have even tried the no-water-change-method-for-several-months-at-a-time and found it worked quite nicely, but I did use soil as the substrate, and I only had a few snails in the tank with plants and a few guppies (in a 125 g tank). This setup worked out nicely in the end since there wasn't a large buildup of fish wastes/over feeding, and I didn't need to worry about dosing ferts so the inputs were few and the outputs from plant trimmings were high. Overall the tank went without a water change for at least 6 months and could have gone longer.


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## Endler Guy (Aug 19, 2007)

Well, I didn't mean to make you feel bad. It probably happens a lot - people not knowing where they're posting and only responding to the titles of posts. I read one a couple of days ago about a guy with BGA. Diana did respond in that one but what a discourse that was! All kinds of people were talking about antibiotics, water changes, TB, and so on. He ended up going the natural route even though it took a month, it was successful. http://www.aquaticplantcentral.com/forumapc/el-natural/42265-blue-green-algae-control.html

It's a bummer your guppies and snails didn't breed in your 125 gallon like mine are in my 10 gallon. I must have about 50 of them in there and when I got them, they were all diseased and sickly. They were feeder guppies. They are breeding like there's no tomorrow and they get bigger every time I look at them. The plants are really taking off in there too.


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## dwalstad (Apr 14, 2006)

I've not done water changes for many months and have replaced a lot of evaporated water. Yesterday, I tested the water with my conductivity meter. This gadget measures the electrical conductance of salts (anions and cations like Na+, Cl-, K+, etc) in the water.

The gadget's principle is simple: The more salts in the water, the more the water conducts electricity. I predicted that my tanks would have very high conductivity readings suggesting a huge salt build-up. They didn't.

Here are the results (all in mS/cm2):


My Tapwater: 0.31 mS/cm2
45 gal tank: 0.32
50 gal tanK: 0.44 
55 gal tank: 0.37
0.05% solution (or 5 ppm) NaCl: 1.13

Studies of aquatic plant composition show that plants take up salts like NaCl that they don't need or use. However, I didn't expect that they would do such a good job. Hurrah for plants!


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## Endler Guy (Aug 19, 2007)

dwalstad said:


> I've not done water changes for many months and have replaced a lot of evaporated water. Yesterday, I tested the water with my conductivity meter. This gadget measures the electrical conductance of salts (anions and cations like Na+, Cl-, K+, etc) in the water.
> 
> The gadget's principle is simple: The more salts in the water, the more the water conducts electricity. I predicted that my tanks would have very high conductivity readings suggesting a huge salt build-up. They didn't.
> 
> ...


Thanks, that's nice to know! Come to think of it, terrestrial plants such as celery and tomatoes are high in sodium (for plants). It makes sense that aquatic plants would take it up too. It looks like your 50 gallon might have more evaporation or the plants in that tank don't take quite as much up.

NPTs and your methods ROCK!:clap2: Even though it might cause some people to hyperventilate and keel over:jaw: . You might want to put a disclaimer on the next edition of your book. LOL!


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