Are Large Water Changes Killing Fish? Small vs Large Water Changes -

[Gourami Swami]

My water is on the hard side, and does not increase much in pH after time, that I can tell. Interesting theory though. I think there is often a lot more going on in our tap water than we can tell with a simple API test.

 

[RD.]

Our winter water is full of dissolved gasses. The pH doesn't shift much but the gasses do have a negative impact on various species of fish. I stopped keeping those species do to how the gasses impacted their slime coat. (peeled off like gobs of snot when performing large water changes)

https://www.thekrib.com/Diseases/gas-bubble.html

 

[FishEZ]

In my fish room I have a routine that basically instead of changing 90% once a week, I change 50% twice a week using RO water only. Not everyone is setup to do it like that but in my case, it's convenient. However, on occasion I've done close to 90%. My belief is that the good bacteria is in the filter media. I do NOT change the filter media and at the same time large amounts of the water. The water changes remove the nitrates and keeps those numbers down, but the bacteria is usually not harmed. Never had a problem, and the fish are thriving. All water is recycled, my "organic" water (high in nitrates) goes out to the garden and trees.

 

[Hendre]

In my fish room I have a routine that basically instead of changing 90% once a week, I change 50% twice a week using RO water only. Not everyone is setup to do it like that but in my case, it's convenient. However, on occasion I've done close to 90%. My belief is that the good bacteria is in the filter media. I do NOT change the filter media and at the same time large amounts of the water. The water changes remove the nitrates and keeps those numbers down, but the bacteria is usually not harmed. Never had a problem, and the fish are thriving. All water is recycled, my "organic" water (high in nitrates) goes out to the garden and trees.

I'd be seriously worried with straight RO, you probably won't get PH crashes with that many water changes however RO has basically nothing in the way of hardness. Nothing to buffer, and no minerals for plants and fish. I'd just be careful

 

[tarheel96]

tarheel96 not sure why you tagged me, didn't have a chance to read the whole thread. Water changes depend on individual situations. I am fortunate to have hard water so my water stays stable with large water changes but I focus on temperature. I did crash my filter before though. I changed over to a matten filter which needs much longer to stabilize. I did not give it time and continued with large water changes. Result was minicycles and ammonia

I remember seeing your name on a thread discussing large volume water changes and thought you might have been someone who had problems with big water changes.

It's good to hear you say that you're fortunate to have hard water. Too often I hear people looking for a reason to find some kind of problem with hard water. I have extremely soft water (~1.75dGH, ~1.5dKH) so I can appreciate the stability that comes with high carbonate hardness. If I don't add carbonate alkalinity in the form of HCO3 the nitrifying bacteria won't work for long ... and not very well. I also add calcium, magnesium and other minerals to some tanks so I'm essentially making the water harder and more alkaline like yours.

 

[Galantspeedz]

If the pH strait from the tap starts of lower and then increases to a higher pH after sitting in a cup or bucket after a day, then water contained CO2 from the tap.

It could exit the tap at pH 6.2 and increase to pH 7.2 after a day or it could exit the tap at pH 7.6 and increase to pH 8.2 after a day. Either way, it increases.

If it does this let me know.

Just saw this. Will try it tomorrow.. thanks

 

[nzafi]

tarheel96 you read correctly but my issue was doing large water changes on an immature filter. Caused pain still but luckily I keep hardy fish. I will say I have never tested tap ph but have no reason to believe I have high co2. I have since moved to a daily drip which is a godsend. About 20-25% daily and 80-90% changed in a week.

 

[Jhay3513]

tarheel96 you read correctly but my issue was doing large water changes on an immature filter. Caused pain still but luckily I keep hardy fish. I will say I have never tested tap ph but have no reason to believe I have high co2. I have since moved to a daily drip which is a godsend. About 20-25% daily and 80-90% changed in a week.

That’s literally the first thing I’m setting up when we finally buy a house

 

[FishEZ]

I'd be seriously worried with straight RO, you probably won't get PH crashes with that many water changes however RO has basically nothing in the way of hardness. Nothing to buffer, and no minerals for plants and fish. I'd just be careful

Thanks for the concern. In the past other's have mentioned this. However, I have tested the water after running the RO filters and I have found that the water is NOT completely devoid the water of all minerals in the way of hardness. However, it is greatly reduced. I will be doing further testing the next time I do a filter change to see if the results are different before and after the filter change.

--and PS, I have no live plants.

 

[Hendre]

--and PS, I have no live plants

How boring

As long as everything is maintained and works