# a ramble on water change



## pop (Aug 29, 2012)

Hello Friends,
I have been considering the impact of water changes on our finned friends. Changing your aquariums water is not just the opportunity to interact with the aquarium but changing the water has a direct impact on aquarium residents, just consider having your physical environment temporary removed and then replaced creating an environment that is the same yet very different. This difference of suddenly change of water quality, a water that no longer contains communicating hormones that transmit necessary information about the existing environment. It is through these lost hormones that fish are able to resolve critical issues such as flight or fight which is a stress induced situation. In stress induced situations there are energy allocations consideration, decisions that each fish must resolve. One choice the fish may experience is shutting down some physiological process and enhancing other physiological processes such as reallocating energy from osmoregulation to muscles to increase the possibility of successfully escaping a perceived threat that may not exist and is only perceived due to the lack of communication.
pop


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## superswimmer (Apr 7, 2015)

So are you saying people should never do water changes? You are gong to get a lot of people who disagree with you on that...


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## pop (Aug 29, 2012)

Hello Friend,
I am saying is that when one changes tank water there is a greater impact on tank inhabits than the positive notion of nitrate removal and mineral replenishment. Fish communicate with each other as well as control physiological processes through the release of hormones and the sudden loss of these expected hormones may have an unexpected affect. 
pop


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## corina savin (Jul 11, 2012)

Functions of pheromones in fish are not entirely understood.
While some pheromones appear to be involved in dominance, mating, alarm, shoaling and migration, others are signalling "crowding".
Since our fish tanks have dense population (higher than in any natural body of water), the accumulation of "crowding factor" adversely affect growth and spawning.
I don't see how removing pheromones during a water change have a negative impact on fish.


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## Tolak (Nov 13, 2012)

If you're doing a 50% water change on a 20 gallon, you're removing half of everything, not everything, just diluting it by 50%. Moving that same stock to a 40 gallon would have the same effect, though more long term. Never heard of anyone having a problem doing just that. In the wild the stocking level is much less than in most tanks, somehow with the diluted hormones & such the fish get by just fine, to the point of countless species breeding that we can't accomplish in an aquarium.


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## beaslbob (Oct 17, 2012)

Assuming

1) something is changing at a common rate.
2) that something is linear.
3) water changes are conducted at a constant percentage of change and at a constant frequency.
4) enough water changes have been conducted so the concentration of "something" is constant water change to water change

what is the concentration of "something"

Ans:

(concentration of something before water change)=
((change of something between water changes/(fraction of water changed))
+
the concentration of "something" in the replacement water.

For instance:

assume nitrates increase a 1ppm/day
water changes are conducted with 0 nitrate water at a level of 10% every 10 days

nitrates before water change=(10 days*1ppm nitrate/day)/(1/10)+0
=10/(1/10)+100ppm

to me what is important is to get the rate of change down by using such things as plants or (in marine tanks) dosing what is being consumed.


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## Warhawk (Feb 23, 2014)

Sorry but I'm confused. Your saying the fish need the build up of hormones in the water. 

But in the wild if the fish lives in under a plant in the stream or creek they will have fresh water coming in all the time they don't have that build up your talking about. And yes they will have hormones from other fish passing thru their home it will be super diluted. 

So it keep the amount of hormones low like in the wild shouldn't I do more water changes? 

The build up of hormones isn't a good thing. When your fish are growing you want to do more water changes to keep those hormones levels low. Fish give off hormones that will stunt other fishes growth, it doesn't matter if they are their own hormones because they are the only fish in the tank. So if you don't do enough water changes you will have stunted fish or even unhealthy. 

I could just be me but I don't understand your point,


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## superswimmer (Apr 7, 2015)

I understand the point, but I don't necessarily agree with this either.
Fish give off a lot of other things, including ammonia, which we all know is extremely toxic. How are you supposed to remove all of the toxins produced by the fish? In the wild, evaporation and current do this, but in the fish keeping world, a siphon is needed to do.
I definitely agree with whoever said that the water comes and goes in a stream and such all the time.


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## beaslbob (Oct 17, 2012)

What I'm saying is that any level of water changed convenient to the fish keeper will not prevent the buildup of changes to the tank. a 1/10 water change every 10 days results in 100 times the daily change between water changes. a 1/5 water change every 20 days results in 100 times the daily change between water changes.

In order to keep the build up below the daily change you need to do at least a 100% daily water change.

As far as the hormones go I have kept a heavy bioload (~30 guppies/platties in a 10g tank) for up to 9 years. (from the original cycle trio.) So I'm not worried about hormone build up.


my .02


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## corina savin (Jul 11, 2012)

Pop was talking about pheromones released by fish under certain circumstances. Those are very potent (active at low doses) "communicators" between fish of the same species that enable their surviving in the wild. Because these are organic substances, I assume that they have a short half life and can easily be removed by carbon in the filter.
Nitrates are stable inorganic compounds and are constantly produced as long as you feed the fish.
Bob. My math is not strong, I must admit that I didn't understand your math model.
10% water change is not enough to keep up with the rising nitrates but you don't need "at least 100% daily" as you stated either.
Let's assume that the nitrates are rising at a rate of 4 ppm per day in a fully stocked non planted tank. We dose ammonia at this rate to complete fishless cycle, right? 
Let's say we start with 40 ppm, another 28ppm are formed in a week and we do 50% water change every week
40+28=68 reduced by half with a 50%wc
34+28=62 another 50% wc
31+28=59
29.5+28=57.5
28.75+28=56.75
28.37+28=56.37
28.18+28=56.18

If you continue with 50%wc weekly, you will remove exactly 28ppm nitrates which is what was produced in a week.

Same thing if you start with...let's say 20ppm

20+28=48 followed by 50% water change
24+28=52
26+28=54
27+28=55
27.5+28=55.5
27.75+28=55.75
27.87+28=55.87

After few more weeks, the numbers will be 28+28=56


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## beaslbob (Oct 17, 2012)

A 50% water change in a system that increases 28ppm between water changes will have 56ppm before the water changes (plus whatever is in the replacement water). That is where it winds up. The end point.
it is 56 before 28 after and back up to 56 before the next water change.
and if you want to limit the buildup to the daily increase, you must change all the water at least every day.


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## Kim (Apr 30, 2008)

I'm not sure I agree with the math here. Say the fish produce a set amount of any compound (nitrogenous waste, hormone, etc) per day. If you change out a specific percentage of the water every 7 days or so, you can graph the change in the concentration of the compound over time. If you measure the concentration AFTER each weekly water change, what you get is a hyperbolic curve, where the tank eventually establishes a relatively constant level of the compound in question. Yes, the concentration will increase over the course of the week, but it will return to this baseline level after a water change. So in effect, you are getting a steady range of concentrations that within which the actual concentration of the compound will remain. Here's an example:

Say the fish produce 1 ppm of the compound over the course of 1 week and you change 50% of the tank water weekly.
Week 1: 1 ppm before the water change, 0.5 ppm after the water change
Week 2: 1.5 ppm before the water change, 0.75 ppm after the water change
Week 3: 1.75 ppm before the water change, 0.875 ppm after the water change
Week 4: 1.875 ppm before the water change, 0.9375 ppm after the water change
Week 5: 1.9375 ppm before the water change 0.96875 ppm after the water change
If you keep going, the function approaches continues to oscillate between what is essentially a range of 1-2 ppm. That is the concentration range within which the substance will remain.

Now say your fish still produce 1 ppm of the substance per week, but you change 90% of the water weekly. Your new stats are:

Week 1: 1 ppm before the water change, 0.1 ppm after the water change
Week 2: 1.1 ppm before the water change, 0.11 ppm after the water change
Week 3: 1.11 ppm before the water change, 0.111 ppm after the water change
Week 4: 1.111 ppm before the water change, 0.1111 ppm after the water change
etc. 

So now your water essentially stays between 0.1 and 1 ppm all the time.

This math makes it evident that you can tailor your water change schedule (percentage and time between changes) to keep the concentration of any substance within a desired range. If you didn't do any water changes, the concentration of the substance may continually increase (if there are no mechanisms for its degradation in the closed aquarium system), or it may establish its own baseline range of concentrations based on half life and other mechanisms of removal from the system (light inactivtion,etc.). Furthermore, even if the substance is degraded, you still have to deal with the buildup of the byproducts of this degradation. The only exception to this might be when you consider nitrogenous compounds in the planted aquaria (where the plants will essentially use them all up), but we were talking more about hormones in this thread. Now, even supposing that the compound has a short half life and/or is removed from the system with carbon, etc, the baseline concentration range for the substance in the absence of any water changes is going to be much higher than if water changes were performed (maybe the range is 35-50 ppm without water changes and 2-5 ppm with water changes for example). For this reason (and because I don't have the time or the equipment to define and investigate every substance that could possibly build up in my aquariums), doing regular partial water changes is the safest way to keep everything within a desirable concentration range. 

Fish don't ever live in completely closed, stagnant systems in the wild, so I highly doubt they will flourish in such conditions in the aquarium, as others have already pointed out. One may argue that if you have a truly balanced system everything will equilibriate at a safe level, but I'd say the chances of this happening are slim to none, and given the numerous substances present in an aquarium, it would be difficult, if not nearly impossible, to determine if your system is actually in equilibrium and if that equilibrium is actually safe for the inhabitants (for instance, the system may reach an equilibrium where the concentrations of a particular substance are within a toxic range).

Just my thoughts on the matter.


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## pop (Aug 29, 2012)

At the local watering hole for fishkeepers.
Duchy: they took over your thread, pop.

Pop: ya all that ciphering just left me with a headache.

Philbert: boring son, I find the story of the sex hormone in goldfish more interesting.

Dutchy: fish have hormones?

Philbert: fish not only have hormones but also release compatible chemical compounds associated with specific hormones that can influence a specific behavior and or development in other members of the same species.

Dutchy: what are these chemical compounds called?

Philbert: phenomes of course! CS post was somewhat interesting. What did you think duchy? 

Dutchy: was it implied that social incidents such as overcrowding can be solved by biology.

Philbert: it was found that male goldfish in overcrowded conditions release a phenome that has the ability to restrict the further release of hormone / phenome that completes the mating ritual (reproduction).

Dutchy: wouldn’t being able to release an interrupter into the reproductive process be back tracken in terms of evolution?

Philbert: at first I would agree with you duchy but after some learning up on evolutionary theory there seems to be a positive aspect to this specific behavior. By reducing the growth rate of the shoal, the shoal is protected from disintegration by the increasing number of members seeking safety. The safety of the shoal for goldfish in a state of nature can also be viewed in terms of stabilizing water parameters and the ability to “cover individual member who may be threatened”

Dutchy: how does this process of hormonal release happen? Is it like a process is there a structure?
 
Philbert: son there is not only a specific process there is a structure that is repeated in species after species. It is a process that can best be described as the dance of nature. There are two necessary notions that must be accepted, hormonal / pheromone release is very specific to fish species and time restricted. A female fish that is ovulating has s short period in which she must exspell the egg for external fertilization. For goldfish this time span is limited to 60 to 80 minutes. In order to meet this time requirement both the female and male fish must act together and synchronize the release of hormones/phenomes to compete the reproductive process. 

As I understand ovulating female releases a small quantity of the sex hormone / pheromone into the water where it is received and recognized in the male fish’s olfactory sense causing the male fish to release greater amount of the sex hormone / pheromone plus genetic material into the water stimulating the female fish to release her eggs for fertilization completing the reproductive process.

Dutchy: changing water can disrupt this continual fragile yet effective method of communication between fish of the same species?

Pop: maybe!

Comments by folks that have experience breeding water critters are needed.


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## beaslbob (Oct 17, 2012)

Kim

FWIW fish in the wild do live in a closed environment called planet earth. 

On your water change schedule a 50% water change weekly will result in twice the weekly build up just before a water change. 
a 90% results in the weekly water buildup/(9/10)=the weekly build up*10.9=1+1/9.
Which agree with your examples.

Plants to much more than recycle nutrients and return oxygen. In one scientific experiment, macro algaes were exposed to various level of coppers. At 250ppm copper for two weeks exposure the macros went from 30ppm copper to 1050ppm. The results were that the macros accumulated copper linearly with the exposure values and the amount of time exposed. Steady state had not be achieved. FWIW 250ppm copper is higher than 60% of the at faucet values in major cities in the US.
Additionally, dried macro algaes are used to clean up industrial waste water. In that use they are a one pass system that removes various nasty ions. And the macros can then be "regenerated" as well. Living plants and macros consume many metal ions and other toxins as they "suck out" the ammonia/nitrates/phosphates and minor nutrients as well.

Obviously the earth pretty well takes care of hormones as we have many fish in the world. Our only job is to do the best we can so that a tank can last a couple of years or so. Of course 9 years in a 10g tank with 30 fish including a half dozen reproducing adults with no water changes and no mechanical filtration/circulation is close enough for me.

Still that's just my .02


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