Changing water in smaller increments

[squirley]

Does anyone do their WC in smaller amounts? Such as 5% once a week instead of 20% monthly. I believe it may be better to change out smaller percentages of water in the WC because all of the water parameters recommend small changes to stats like pH and salinity. If this is the case then changing out 20% of the water all at once might increases the range that the water parameters go from high to low or low to higher ratings.

 

[Fishmanic]

It is best to do larger water changes to remove water pollution from fish waste, rotting leaves etc. At minimum, I would change 50% or higher each time. I go about 3 weeks between changes on my 5 gallon tank and then do a 75% water change. I only have 2 tiny ember tetras in the tank so due to low stocking, I can increase time between changes. If I had a fully stocked tank, I would do a large WC every 7 days.

 

[Magnum Man]

I think the idea is that the clean water coming in, is better than the tank water that your fish have been pooping in for a month... in a perfect world, I would change every week... sometimes it goes as long as 3 weeks, and my water charge draw tube is 9 inches long, so I estimate I change between 1/3, and 1/2 the water each change, depending on tank dimensions

 

[Essjay]

The late Byron explained the reason behind regular water changes -

Regular Partial Water Changes

Byron Hosking November, 2010 (rev April 2021) Nothing is more important when it comes to aquarium maintenance than regular partial water changes. The adage “an ounce of prevention is worth a pound of cure” certainly applies here. One frequently reads of products that will reduce the need for...

www.fishforums.net

 

[Gertrudae]

That depends – some fish cannot tolerate major changes in water chemistry. For this reason, they are rarely found in stores.

If you change 5% daily instead of 35% weekly, you are effectively changing less water. You can think of it as removing some of the water that you changed the day before and the day before that, and so on. After a week, there is less fresh water in the system than if you had done a single, larger water change of 35%.

I do not carry out regular water changes in almost all of my aquariums. But they are only very moderately stocked and there are lots of plants. This has worked well for decades. Fish faeces are converted into nutrients for the plants, rotting leaves provide welcome humic substances, and I have snails that help break down organic matter.
However, some fish with high demands for fresh, flowing water are not happy with this regime and get the usual water changes.

There are so many ways to go!

 

[Rusty_Shackleford]

I perform weekly water changes faithfully, every Monday. Once every so often it gets pushed till Tuesday, but I never ever miss a water chamge amd think oh I'll just do it next week.
I do however change less water in the winter months and more in the warmer months. This is done for a couple of reasons, first I want to simulate a difference between thr warm wet season and the cooler dry season. I also want to avoid nitrogen bubbles in my water during the cold months where the tap water feels.line ice water .

 

[gwand]

That depends – some fish cannot tolerate major changes in water chemistry. For this reason, they are rarely found in stores.

If you change 5% daily instead of 35% weekly, you are effectively changing less water. You can think of it as removing some of the water that you changed the day before and the day before that, and so on. After a week, there is less fresh water in the system than if you had done a single, larger water change of 35%.

I do not carry out regular water changes in almost all of my aquariums. But they are only very moderately stocked and there are lots of plants. This has worked well for decades. Fish faeces are converted into nutrients for the plants, rotting leaves provide welcome humic substances, and I have snails that help break down organic matter.
However, some fish with high demands for fresh, flowing water are not happy with this regime and get the usual water changes.

There are so many ways to go!

Many of the cognoscenti on the forum frown upon the idea of self sustaining tanks. Out of ignorance I hold no opinion. Give me an example of one of your self sustaining tanks. Tank size, livestock, plant density, substrate and GH etc. What are the important elements that contribute to a successful equilibrium?

 

[FranciscoB]

….such as 5% weekly versus 20% per month…
This is foreign to me. I change between 80-90% weekly in all my tanks. Occasionally, two of my tanks don’t get their change for two weeks. I, and the fish notice the difference and suffer for it.
If water is of similar parameters, it is just not true that some fish don’t take well to larger changes. Or, I see no proof of it, but see proof that skimping on water changes is deleterious.

 

[GaryE]

With my more delicate species, a large water change after weeks of neglect can be fatal. The chemistry of the water in the tank changes, and I want to keep it as close to what comes in fresh from the tap as I can. 5% would allow the tank to drift quite a bit, as would a monthly change. I'm on a weekly schedule that sometimes slips to 10 days. I do 30%, although in winter maybe 20-25% in some tanks due to saturation and limited hot water in the small heater.

You can approach it backwards, but long stretches with minimal changes cause serious changes in the tank water. If you are aiming for stability, then you need large water changes at least 3 times a month, unless you have species from swamps that have evolved in tune with water conditions that might kill other fish. It's not necessarily the fresh water that changes conditions, but rather the water that's in the tank, with fish, plants, bacteria, archaea and substrate that becomes different.

Some fish species are adapted to swamps. Most aren't. I'm not changing 120% monthly as new water mixes with old, but a 20 gallon tank here goes through 18 to 24 gallons a month.

 

[squirley]

The late Byron explained the reason behind regular water changes -

Regular Partial Water Changes

Byron Hosking November, 2010 (rev April 2021) Nothing is more important when it comes to aquarium maintenance than regular partial water changes. The adage “an ounce of prevention is worth a pound of cure” certainly applies here. One frequently reads of products that will reduce the need for...

www.fishforums.net

great stuff, i did a WC after reading that!!

 

[squirley]

That depends – some fish cannot tolerate major changes in water chemistry. For this reason, they are rarely found in stores.

If you change 5% daily instead of 35% weekly, you are effectively changing less water. You can think of it as removing some of the water that you changed the day before and the day before that, and so on. After a week, there is less fresh water in the system than if you had done a single, larger water change of 35%.

I do not carry out regular water changes in almost all of my aquariums. But they are only very moderately stocked and there are lots of plants. This has worked well for decades. Fish faeces are converted into nutrients for the plants, rotting leaves provide welcome humic substances, and I have snails that help break down organic matter.
However, some fish with high demands for fresh, flowing water are not happy with this regime and get the usual water changes.

There are so many ways to go!

Do you ever worry that the snails wont get food. I drop algae wafers for them and sometimes they pass right by them.

 

[Gertrudae]

Many of the cognoscenti on the forum frown upon the idea of self sustaining tanks. Out of ignorance I hold no opinion. Give me an example of one of your self sustaining tanks. Tank size, livestock, plant density, substrate and GH etc. What are the important elements that contribute to a successful equilibrium?

This tank (130*50*50 cm / 325 lt)stood here from 2004 to 2023. There were always Endler's Guppys and one or sometimes two Ancistrus in it. The Guppys lived there unmanaged all the time and still do in another tank.

Over time, it housed several other species, from small tetras to dwarf cichlids and badis.

No filtration, usually no flow pump, very rare water changes.
I never used fertiliser or additional CO2.

The aquarium had no heating, the temperature was between 20 and 25 degrees Celsius.
Hard tap water KH 24 / GH 28.

The substrate consisted of natural gravel with a grain size of 0 to 20 mm, which came directly from the gravel pit. Over time, it became very hard, but still looked like new when I finally removed it. So this substrate had no influence on the water chemistry. On top of this was a layer of mulm, well-structured reddish-brown flakes. This formed by itself. I never vacuumed the entire bottom. The plants grew well in this substrate.

The mulm is a key element – it is home to all the good bacteria, lots of microfauna and a source of humic substances. I supported this from time to time with some dry leaves.

And I think that is the second key – adding natural organic matter, including all the microbes that live on it – leaves, twigs with lichen, living food from small, fish-free waters in nature. Of course I dont treat this with hot water or desinfectants.

Such a system needs time to mature and stabilise. The tank started leaking in 2024, so I replaced it with a new one. This is now my Congo River tank. After a year and a half, it is slowly finding its stability. It still needs pumps for water movement. Occasionally, I change some of the water when I need to remove the cyanos, which have been a problem for quite some time now. At the moment, they don't seem to be growing back after I added a large amount of catappa leaves.

 

[GaryE]

I think @Gertrudae 's Congo region tank answers a lot of questions, while asking more.

In flood, the Congo river delivers over 2.5 million cubic feet of water per second into the ocean. In dry season, over 800,000 cubic feet (per second). That's a significant water change for any small fish surviving along its edges.

It isn't one habitat. In the rolling waters of the chain of mega rapids along its course, few fish can survive. At the end of every rapids is a massive eroded scoop so deep there's no oxygen. So the distribution of species is broken up, and what's in the huge slower zones between rapids can change, rapids by rapids. The shallower areas along the sides are rich in Steatocranus and Orthochromis Cichlids, poor swimmers with reduced swim bladders. That keeps them from being swept away to die. Nanochomis thrive, along with Characins. You don't keep them in still tanks, and with no water changes, they don't live long.

There are the 'lakes', the slower zones, and they feature larger fish with a few Characins that creep into the hobby. One, Lake Mweru, has an assembly of Pseudocrenilabrus Cichlids that rivals Lake Malawi for diversity, although few are colourful enough to interest aquarists.

Every great river has thousands of creeks feeding in, and in the Congo, a lot move rapidly downhill into the main channels. There we get smaller Characins, dwarf Cichlids (Congochromis) and a lot of killies, barbs and catfish.

We also come close to @Gertrudae 's idea of the swamp tank, with huge marshlands feeding the creeks. In dry season, they can be cut off, or even dry up. The fish in them have adaptations to poor conditions, and higher organic pollution, in a trade off for fewer larger predators being able to survive. Those are the fish people can keep in swamp tanks.

There are similar habitats with fish evolved for them in Asia and South America, and if a hobbyist is prepared to do research and identify what fish come from the roughest places, they can have great swamp based set ups. It's important not to decide because one Congo region fish thrives in an unfiltered tank that all will. Likewise, don't base assumptions on the rapids edge fish that come from highly oxygenated water. Their conditions won't work for a tiny swamp killifish. Fish by fish, species by species...

Swamps often have interesting plants, and often appeal more to plant keepers than fish aquarists.

I notice @Gertrudae uses a water pump to move the water, an overlooked side of filtration. Sometimes my tanks for slow water killies have fairly inefficient filtration, and at times, I think it's my water changes that keep the fish alive, not my filters. I have a Congo species from far away from the main Congo River I've kept and bred for 35 years (because I like them) and their lifespans have increased since I retired and could do more consistent water changes. I regret not having learned that sooner.

 

[Magnum Man]

I don't think you can ever really go wrong doing water changes... on particularly sensitive fish, you just may need to match their water more closely than others, and a person should always do due diligence to see what water parameters your particular fish prefer...

I don't have any fish that sensitive, but if needed, you could match their water parameters, in another tank, bucket, or container and preheat it to match the tank you are changing the water on... this includes pretreating to remove chlorine if applicable... mine get 1/3 water changes with room temperature RO water, and that has worked well with all the fish I have..

 

[GaryE]

I don't have any fish that sensitive, but if needed, you could match their water parameters, in another tank, bucket, or container and preheat it to match the tank you are changing the water on... this includes pretreating to remove chlorine if applicable... mine get 1/3 water changes with room temperature RO water, and that has worked well with all the fish I have..

Wait, didn't you have Phenacogrammus auriantacus? Didn't you have a tank of African tetras from the Congo? Those can be very delicate fish, and with water changes, you've managed them (unless disaster has struck in the meantime, as it does for many who try these challenging fish).
A little work and appropriate water gets results.