[collinm]

When people say that they are "water changing", is the reader to assume that the tap/RO/DI water that is being added is pre-conditioned (beyond de-chlorinator) to the pH, hardness, and alkalinity of the current aquarium?

How dangerous is it to do a 50% water change of only de-chlorinated tap water? Let's assume that the current aquarium water has deviated .4 pH (an upper limit) from the original tap water pH, which is about to replace the old water.

 

[roadmaster]

People are assuming that regular weekly water change's are being performed which would prevent water in tank from deviating much from that of the tap water /source water unless one is taking measures to adjust said water.
Dechlorinator is always wise to use for new water if the lion's share of makeup water comes from the tap.
If water in the tank has drifted away from source water(pH.GH),then smaller more frequent water changes rather than one large one would be less stressful to fishes/invert's.
Fishes attempt to adapt to the environment they find themselves in, they must or they perish.
Sudden changes,even for the better, sometimes are stressful. So smaller changes over time would be my aim if water changes have been few and far between.

 

[collinm]

Makes sense. Gotta keep up with the chores. I have found that my water can really change from tap water qualities in a week. With 30-40% water changes every week. A damned batch of Eco-Complete, and before that, 20% of the tank being driftwood.

Let's say I needed to water change because something toxic got into the tank. Too much fish medication. Or there's a huge algae bloom and I'm trying to find a solution as fast as possible. Crunch time.

Is there any kind of rule of thumb for how much and how fast one should change out water? Maybe a ballpark range as to how much time it takes a fish to adjust (osmoregulate, reach equilibrium, whatever) to a certain pH shift? I know this is technical, but someone must have done the chemistry at some point.

Appreciate the input

 

[roadmaster]

Toxic substance or too much medication would kill fish much more quickly than pH shift over day's, so I would choose immediate 70 to 80 % water change and perhap's another 12 hours later to remove toxin's .
Would run fresh carbon pouch in the filter after said water changes for a week minimum, which is about all the longer the carbon would remain effective at adsorbing residual's.
pH shift's happen daily and or weekly from natural biological processes and or mechanical ly induced such as with CO2 injection.
Fishes do not mind these fluctuation's over time, nearly as much as they might react negatively to sudden change in GH.(they feel this acutely)
Some species more affected than other's.
Chasing some magic pH number with pH up or down product's is quickest way I know to create stressful condition's in the aquarium .
Better to keep fishes that can adapt more easily to your/my water, than to try and alter the water to suit the fish unless one is fully aware of what the adjustment is gonna result in.

 

[waddo]

40-50% weekly change with dechlorination. You don't need to worry about the fine details unless perhaps you have some very delicate fish. It's not rocket science and the chemistry may be of interest to some but the fish and shrimp don't seem to care.

Waddo

 

[PlantedRich]

One major reason to NOT try to chase a magic number is when you do find a crisis. I recently had a major problem with overdosing CO2 and had to do a major water change. I keep a reserve barrel of water on hand but the change required more than on hand so new cool tap water was required or the fish were going to die right then. Since I do not treat other than dechlor, I was able to run as much water as required and only worry with the temperature. I dealt with the temp by using hot water. Had my tank been treated in other ways, my fish would have died.
I find it far better to have stable water than to have "recommended " water. I lost no fish but it was close!

 

[Nordic]

Find something that works for you and the fish. A fish kept in dirty water for long will respond more negatively than one used to water changes.

 

[Hoppy]

Fish in natural bodies of water get sudden influxes of rainwater, which can be low pH due to atmospheric CO2 and gaseous contaminants. Unless it is an extreme case of acid rain the fish don't die from that. I don't even measure the pH of my tank water, and have never had a fish die after a water change. I also do a 50% water change, then dump in a teaspoon of GH builder. That, too, doesn't harm the fish. They just aren't that delicate as a general rule. This doesn't mean that there aren't some delicate species, but they are the exception, not the rule.

 

[secuono]

I have well water, I don't do anything other than adjust the faucet to get a similar temp of the new water to the old water. I don't need to add anything to my new water.
The pH I don't worry about, as I don't have fish that are super sensitive to pH changes.
I change 55 gallons of water in my 75gal tanks every week.

When I had city water, I would add the dechlorinator into the water stream as I was adding the new water. I didn't fill buckets and put the dechlorinator in those. Again, I'd try to match the temps of the new water, to the temps of the old water. I only changed about 30 gallons at a time back then. I didn't worry about anything else.