Opinion on frequency of water changes

[Charleston Cory]

Hi folks, I maintain quite a few freshwater fish tanks (no brackish or no African Cichlids. I am also really learning the value of maintaining a well planted tank.

i was just looking for an opinion because when I watch videos or read, it seems like their all schools of thought. I do water changes, sometimes weekly, sometimes bi weekly and even a month or tad more.

what I was wondering, if I come across a tank that (regardless of when the last water change was) if all my test parameters are excellent and the fish and tank look fine) would it be fine to leave the existing water a little longer. Naturally, if the parameters are safe but starting to even slightly creep into a range in the wrong direction, I either do the change right away or within a day. I really find it weird that I would be tossing water for other water, when parameters are really good.

Also as an aside, sometimes a water change results in a death. I don’t think there is really much to it other than coincidence, but it sometimes gnaws at me. I feel responsible for the death or deaths. I recognize temperatures are important to remain consistent when changing. Trust me, I do experience a death on occasion when not changing the water so frequently so I do not know if this is relevant.

I am just curious about how other people maintain there tanks, and just like to hear some pointers, etc. I might have overlooked.

I am a big Aquarium Co-op guy and respect the members opinions in this community. Thanks all have a great evening. Yes it is 2:25am EST here, but insomnia and fish planning and always thinking and trying to do better has me restless tonight.

thanks in advance for any input you can offer.

Cheers,

Charleston Cory

[Mmiller2001]

Water changes should not cause any deaths. If this a frequent issue, I would be concerned. Steps I would take, use a tub or similar to fill, add a pump or air stone, declorinate as soon as the storage is filled and add heaters to keep the water near tank temperatures and to off gas excess CO2. 
 

Water changes are incredibly important in a planted tank. Organics, soluble and insoluble, will build up and cause problems. You can’t test for these with hobbyist level test kits, but need to be removed. I prefer 50% weekly and often do near 90% when I really want my tank to look the best possible. 50% makes calculating nutrients easier and is why I mostly stick to this amount.

This tank received 60% weekly and 90% twice a week 1 month before the AGA.

I’ll add that water changes also replace Macro and micro nutrients. For example, Calcium and Magnesium (GH). In many ways, water changes keep the tank water stable. You don’t see all in one fertilizers with Calcium and contain insignificant amounts of magnesium.

Edited April 29 by Mmiller2001

[NOLANANO]

On 4/29/2024 at 1:25 AM, Charleston Cory said:

what I was wondering, if I come across a tank that (regardless of when the last water change was) if all my test parameters are excellent and the fish and tank look fine) would it be fine to leave the existing water a little longer.

If your parameters are fine, no need for a water change. I actually do water changes more to replenish the nutrients in the water for my plants than for my fish.

Now as for the deaths:

1) How old is your tank though? The reason I ask is that newer tanks tend to have more deaths than seasoned tanks. 

2) Do your fish act stressed or different after a water change? Its possible that the local water supply has something in the water that is irritating them and killing the weak. Usually an air stone can fix this issue.

[madmark285]

The solution to pollution is dilution. As @Mmiller2001 says, you can't test for alot of the crap in your tank. 

[jwcarlson]

I'm worried about next to nothing that I can actually test for in a tank.  Once you get a good feel for your water and your "systems" in general, you end up kind of knowing where all that stuff sits just by observation and the general passage of time since your last water change or test.  I might have a fry tank with nitrates 0-5 ppm that by conventional wisdom "doesn't need a water change".  But I'm absolutely changing water in those tanks as large and as frequently as I can manage to do reasonably.  As others above have stated... there's next to nothing we are actually capable of testing in our water.  And those are all of the things that I'm worried about.

Edited April 29 by jwcarlson

[anodyne99]

Since an aquarium is an enclosed box of water and can't ever really mimic the biodiversity and chemistry of a true ecosystem, it seems unlikely that the substances monitored for by test kits are the only relevant variables. Fish emit hormones and shed bacteria and viruses and there are all sorts of plastics in our tanks and water, just so much more going on than the standard API kit can tell you about. 

I say that as someone who once killed a tank of beloved 7-year-old goldfish with a water change done when my city switched to a different water source due to contamination one summer. I understand that there is some risk to a water change. I prefer to manage that by testing new water before it goes in the tank and maintaining stability by regularly changing out old water with all the accumulated bacteria, hormones etc. for fresh water with the same basic parameters. 

[NOLANANO]

I am being straight up educated like a 3rd grader in Science class in this thread. I have literally never seen or heard anyone mention anything other than the things we test for plus maybe some trace elements that plants need. But thinking about it logically, of course there is so much more in the water than we are aware of.

[AllFishNoBrakes]

Well, you get varying schools of thought here, too. Welcome to the internet!

I’ve always focused on consistency vs. chasing parameters. I also have super soft water, with little to no buffer, and a lower pH. Because of this, I water change consistent every week. I want to replace the trace amounts of minerals that my water has. 
 

If I go on vacation or something I have no problem skipping a week. But if I’m home, I water change the same amount on every tank, every week. 

[doktor zhivago]

I usually do 25-30% once a week or so. I find the nitrates climb too high if I let it go for two weeks.  I try to stay between 20 & 40 ppm nitrates, even tho it's fine to get higher, that's the sweet spot I try to keep the tank in.