Water change routine

[AlexT]

Interested in opinions with alternatives to 50% water change a week from the perspective of this..

If I did a water change every 2 days, what percentage of water would I need to change every 2 days if I was to give the fish the same benefit as a 50% water change once a week?

I'm assuming it's not necessarily a case of simple maths? Or is it? Because in that case, it would be about 14% water change every 2 days (which somehow doesn't seem enough, even though the maths check out).

 

[BrianK]

I only do about 20% once per week. Do you have any plants? And what size tank and what fish? There is more to it than just a simple % change.

 

[AlexT]

I only do about 20% once per week. Do you have any plants? And what size tank and what fish? There is more to it than just a simple % change.

I'm not looking for an individual quote on my exact circumstances. I'm asking generally. If the question cannot be answered, that's okay.

 

[BrianK]

If you put your data into aqadvisor.com, they will give you a recommendation on water changes.

 

[Naughts]

Interested in opinions with alternatives to 50% water change a week from the perspective of this..

If I did a water change every 2 days, what percentage of water would I need to change every 2 days if I was to give the fish the same benefit as a 50% water change once a week?

I'm assuming it's not necessarily a case of simple maths? Or is it? Because in that case, it would be about 14% water change every 2 days (which somehow doesn't seem enough, even though the maths check out).

I know what your saying, each subsequent change will be swapping a % of the newer water as well as the old water, so it is a significantly less effective system. There used to be a chart but I haven't seen it in ages.
Bottom line is big water changes (plus gravel cleans and filter maintenance) provide a cleaner tank.
Maybe you could look at ways to make your water changes easier/ quicker/ more efficient?

 

[GaryE]

This isn't a direct answer, but is, in a way. The big problem with water changes is the time pulling out the gear. I rarely do 50% and tend to 30. If I do two changes in a week, I do two times 30% anyway. The actual percentage is uncertain, and I think unimportant. Sure, some of the newish change goes, but if the tank isn't overstocked, I look at what goes in and not what flows out.

50 is a random number, and below 25 is too little, IMHO. If you try for a calculation, its a maths exercise but not a really practical one. The effect of the water change will vary according to fish wastes, foods used, ferts added, water supplier adjustments, etc.

The effect on your back and on your morale with buckets will be a constant.

With buckets, any change is work. With a hose, you can make life easier, and that is more important than a lot of us realize. The limiting factor in my hobby is water changing. I have about 15 tanks stored I won't set up because I don't have a drilled, automatic system and I know when the work in my large fishroom is no longer a pleasure. I don't calculate water changes in gallons or litres, but in minutes.

 

[Ram419]

I usually never let a tank go for two weeks without a water change. But will wait those two weeks as long as water paramters are good. Nitrates is usually what dictates if I need to do a water change and the % of water I change. Some of my tanks have higher nitrates then others so require more frequent water changes and a larger % of water changed (usually once per week).

 

[GaryE]

I would caution against using water tests to decide on when to do changes. Nitrate levels are important, but there is an awful lot an API test kit doesn't look at that might matter.

 

[Ram419]

I would caution against using water tests to decide on when to do changes. Nitrate levels are important, but there is an awful lot an API test kit doesn't look at that might matter.

Sure, and that is why I stick to changes at least every two weeks.

 

[Essjay]

Since my nitrate never reads above zero, I couldn't use that as marker. My tap water has 3 ppm nitrate according to my water provider and my tester reads higher than zero but lower than 5 ppm. The plants in the tank take care of the ammonia made by the fish so there's no nitrate being made.
I change around 50% weekly as I have low KH. Besides removing everything which builds up it also replenishes KH.

 

[Lcc86]

My tank is only 3 months ish old so I'm still fine tuning, but am doing a 60-70% water change roughly every 8-10 days. I tend to just fit my water changes in around my availability i.e. either a weekend or a wfh day, so it varies each week. It's quite heavily planted now that everything is growing in, and I don't have any big waste producers so I could probably stretch it a bit further if I had to.

 

[AlexT]

My tap water has 3 ppm nitrate according to my water provider and my tester reads higher than zero but lower than 5 ppm.

That's so unfair

 

[TNG]

Interested in opinions with alternatives to 50% water change a week from the perspective of this..

If I did a water change every 2 days, what percentage of water would I need to change every 2 days if I was to give the fish the same benefit as a 50% water change once a week?

I'm assuming it's not necessarily a case of simple maths? Or is it? Because in that case, it would be about 14% water change every 2 days (which somehow doesn't seem enough, even though the maths check out).

If you change 50% once, you have 50% of old water remaining.

If you change 3 times, one immediately after another, then you need to change roughly 20% each time.

The first 20% water change, you have 80% of old water remaining (80% x 100%).
The 2nd 20% water change, you have 64% old water remaining (80% x 80%).
The 3rd 20%, you have 51.2% remaining (80% x 64%), close enough to 50%.

 

[AlexT]

If you change 50% once, you have 50% of old water remaining.

If you change 3 times, then you need to change roughly 20% each time. That’s assuming the fish behave nicely and put out waste on a regular basis, otherwise it would muck up the calculation .

The first 20% water change, you have 80% of old water remaining (80% x 100%).
The 2nd 20% water change, you have 64% old water remaining (80% x 80%).
The 3rd 20%, you have 51.2% remaining (80% x 64%), close enough to 50%.

Thank you!!! I had not factored in the issue about I will also be removing new(ish) water if I do w/c every 2 days. It was only when the ever helpful @Naughts brought this to my attention, and your post adds more detail. Appreciate it.

 

[AlexT]

If you put your data into aqadvisor.com, they will give you a recommendation on water changes.

Thanks, never heard of that before.