Do I need to do water changes as often as I am?

I have the masterkit for testing water, but I found a rhythm with my water changes a while back and determined that I had a good thing going doing 25-50% water changes once every week in my 25g and my 5g. However, the sole fish occupant of my 5g passed recently and so I've been doing tests to make sure I'm keeping up my cycle (I've got snails in there but I worried they wouldn't produce enough of a bioload). I figured, what the heck, might as well check on my 25g while I'm at it. It's been a week since the last water change, and I'd normally do another today, but I just checked and double checked my parameters and I have 0 of everything in both tanks? I checked the expiry dates on all the test liquids, and they all don't expire until 2024 or 2025, so I'm in the clear there.

We do water changes to remove nitrates.. but if there aren't any nitrates to remove, do I really need to do a water change? Should I hold off on doing a water change until I've accumulated nitrates? Any and all advice appreciated!

 

Well if it reads 0 nitrates then you are fine, but it could be faulty or your kit could have something wrong with it. What is your stocking? Just in case.

 

I personally would still do it once a week regardless. There are other minerals that get depleted in the water that the fish and plants need also.

How long have the tanks been running? The 0 Nitrates is kind of concerning. How are you doing the Nitrate test? Its a tricky one.

 

0 of everything isn’t a major concern if the tank is lightly stocked or if you have live plants. If you’re lightly stocked you could just be removing all the nitrates with the amount of water changes you’re doing. Or live plants eat up the nitrates. As long as you have 0 ammonia using the liquid test kit, I wouldn’t worry. You could also bring a sample to your local lfs and ask for testing just to double check.

But yes as stargirl said, there’s other things in the water like minerals that need to be replaced, so a weekly water change is really the best practice

 

I do not water change unless my nitrates are high. I did when my cycle was more unstable but now there is no point. I only top up. My nitrates get eaten by my plants so they're always low.

 

Well if it reads 0 nitrates then you are fine, but it could be faulty or your kit could have something wrong with it. What is your stocking? Just in case.

Well, the 5g has 3 juvenile nerites, 1 adult nerite, and about 15 young ramshorns.

The 25g has 9 glowlight tetras, 1 bn pleco, 1 false cuckoo catfish (moving them to a different tank soon), 5 adult nerites, maybe 4 ghost shrimp, 1 bamboo shrimp, as well as an unknowable number of ramshorns/other pest snails. I also consider it to be fairly heavily planted, so I figure that has a part to play here as well.

I personally would still do it once a week regardless. There are other minerals that get depleted in the water that the fish and plants need also.

How long have the tanks been running? The 0 Nitrates is kind of concerning. How are you doing the Nitrate test? Its a tricky one.

I do dose flourish and flourish excel, but I don't know if they can account for any minerals the fish would be missing out on. The 25g has been up and running for probably 10 years, give or take? And the 5g has been running for about a year and a month.
I do the nitrate test exactly as instructed, although I shake the 2nd bottle for longer than 30s before adding it to the vial because somebody told me it can be inaccurate unless you REALLY shake it beforehand.

0 of everything isn’t a major concern if the tank is lightly stocked or if you have live plants. If you’re lightly stocked you could just be removing all the nitrates with the amount of water changes you’re doing. Or live plants eat up the nitrates. As long as you have 0 ammonia using the liquid test kit, I wouldn’t worry. You could also bring a sample to your local lfs and ask for testing just to double check.

But yes as stargirl said, there’s other things in the water like minerals that need to be replaced, so a weekly water change is really the best practice

I don't know that it's necessarily lightly stocked (mentioned my stocking above ^^) but I've definitely got a lot of plants in there. I won't be able to bring water to my LFS anytime soon because unfortunately it's an hours drive for me to get there, it's in a highly populated area, and they've got restrictions on the amount of people they can have within the store at any one time, which makes it a bit of a hassle to accomplish.
Could mineral replenishment be accomplished with topping my water off and using fertilizers? My water level usually drops about an inch or two each week..

 

Could mineral replenishment be accomplished with topping my water off and using fertilizers? My water level usually drops about an inch or two each week

I can’t give you the exact science behind it, but someone I trust here on fishlore explained how topping off instead of performing actual changes will change the makeup of the water over time, meaning it’ll end up a lot different than the source water. This should be fine for the current inhabitants as they’ll get use to the water as it changes over time, but it’ll lead to a catastrophe if you ever need to perform a large water change with source water that is now so different from the tank water, and it will also be harder for any new fish to adapt to.

 

I can’t give you the exact science behind it, but someone I trust here on fishlore explained how topping off instead of performing actual changes will change the makeup of the water over time, meaning it’ll end up a lot different than the source water. This should be fine for the current inhabitants as they’ll get use to the water as it changes over time, but it’ll lead to a catastrophe if you ever need to perform a large water change with source water that is now so different from the tank water, and it will also be harder for any new fish to adapt to.

This is true and makes sense, old tank syndrome its generally called. But it can take a long time! Lots of fishkeepers find a nice balance to their tank and only waterchange every fortnight or even monthly.

 

I do not water change unless my nitrates are high. I did when my cycle was more unstable but now there is no point. I only top up. My nitrates get eaten by my plants so they're always low.

Are you saying you don't do water changes at all anymore? Just topping off the tank when the water levels drop?

I can’t give you the exact science behind it, but someone I trust here on fishlore explained how topping off instead of performing actual changes will change the makeup of the water over time, meaning it’ll end up a lot different than the source water. This should be fine for the current inhabitants as they’ll get use to the water as it changes over time, but it’ll lead to a catastrophe if you ever need to perform a large water change with source water that is now so different from the tank water, and it will also be harder for any new fish to adapt to.

That's completely understandable, and I think I can see how that would occur over time, but it was never my plan to stop doing water changes altogether. I just figured I could stretch out my water changes to maybe every week and a half? Maybe every other week? Instead of doing them every seven days? I don't mind doing them as frequently as I do currently, but I figured it's nice to know how long I could stretch it before I'd need to properly worry, y'know?

 

I agree with Stargirl and would also like to add that many other dissolved organic solids accumulate in our tanks that we don't test for. There's more to water chemistry than 0,0,0 and "good to go." For example, you could hang a bunch of pothos vines over a literal swamp hole filled with garbage and the nitrates would read 0 after awhile. Obtuse example but effective

 

No. I will do water changes when necessary. Which is not that often as I dont get a large build up of nitrates. That said my tank is only 4 months old so its unlikely at this point I have had enough time for anything nasty to build up. Say it was an old tank and I wanted to refresh it, I would do waterchanges often for a month or so to make sure fish are doing well then make changes. Whilst its new and fish are happy I try to let it be.[/QUOTE]

 

I agree with Stargirl and would also like to add that many other dissolved organic solids accumulate in our tanks that we don't test for. There's more to water chemistry than 0,0,0 and "good to go." For example, you could hang a bunch of pothos vines over a literal swamp hole filled with garbage and the nitrates would read 0 after awhile. Obtuse example but effective

This feels like one of those things that you're always aware of, but don't really think about at the time, if that makes sense haha? I guess I wasn't really thinking about anything beyond the scope of just my ammonia, nitrite and nitrates. I know of course that there are more factors involved with the quality of the water, but I guess what I'm asking is, if I were to leave a water change for a few more days than the 7 I normally do them at, would it be harmful to my tank? Would it effect anything either in the short-term or long-term that I'm unaware of? Could I get away with a water change at 2 weeks without anything bad happening?

 

I do not water change unless my nitrates are high. I did when my cycle was more unstable but now there is no point. I only top up. My nitrates get eaten by my plants so they're always low.

I went down that road once but think of it from this perspective...I have a 0 nitrate tank because of some aggressive houseplants rooted in my filter, so I could literally never change my water and always have 0 nitrates. There really are a lot of other things in our water that we don't test for... you might be okay doing water changes based on your nitrates for awhile but eventually you'll run into issues

This feels like one of those things that you're always aware of, but don't really think about at the time, if that makes sense haha? I guess I wasn't really thinking about anything beyond the scope of just my ammonia, nitrite and nitrates. I know of course that there are more factors involved with the quality of the water, but I guess what I'm asking is, if I were to leave a water change for a few more days than the 7 I normally do them at, would it be harmful to my tank? Would it effect anything either in the short-term or long-term that I'm unaware of? Could I get away with a water change at 2 weeks without anything bad happening?

In a heavily planted environment that might work yea, it depends on your bioload and whats in your water tho. I wouldn't go any longer than that

 

Hi all,
bumblinBee You have a BN pleco in a 25 gallon. That fish on its own is going to mean continued water changes. This species is a poop machine. Personally I don’t keep adult 6 inch BN plecos in anything smaller than a 40 gallon. I do however have many juveniles in smaller tanks with multiple water changes each week.

Now add a school of 9 glow light tetras , 5 adult large snails , 5 shrimp and another catfish that all need feeding most days of the week and I believe you need to keep on top of the water changes.

 

I went down that road once but think of it from this perspective...I have a 0 nitrate tank because of some aggressive houseplants rooted in my filter, so I could literally never change my water and always have 0 nitrates. There really are a lot of other things in our water that we don't test for... you might be okay doing water changes based on your nitrates for awhile but eventually you'll run into issues


In a heavily planted environment that might work yea, it depends on your bioload and whats in your water tho. I wouldn't go any longer than that

Yep makes sense. Tank is still pretty new, sorry I worded badly, I will still do waterchanges but I try not to do them often. I do know that if the fish adapt to some build up you can kill them all when you change something, or new fish will always die as they can't adapt. So I know to not let the tank get very old with no waterchanges.

 

Yep makes sense. Tank is still pretty new, sorry I worded badly, I will still do waterchanges but I try not to do them often. I do know that if the fish adapt to some build up you can kill them all when you change something, or new fish will always die as they can't adapt. So I know to not let the tank get very old with no waterchanges.

Yup that sounds fine, this applies to the extreme with shrimp.. anything over 20% is unsafe and could cause osmotic shock. 20% is a but much too even, 10-15% is more acceptable. I only change out that much in my tanks with shrimp now thanks to some good advice from the shrimp experts here

There's a bit of a misnomer in what you're saying though, if we're talking about fish then sometimes those problems happen from waiting too long between changes. For example, if you wait until your nitrates hit 160 ppm or something and its been 3 or 4 weeks and you do a massive change then the potential is pretty high that your fish will suffer. Now, if you do large water changes weekly, say 40-60% like a lot of members here do, then the change is much less severe because most of the water gets cycled out every 7th day.

You are right that you should tailor your schedule to this fish you have stocked, absolutely. Take a goldfish pond for example, the nitrates will typically always run high and they're often controlled with secondary interventions a lot more, ie. different types of media designed to remove nitrates, large bio filters, tons of floating plants, etc

 

Hi all,
bumblinBee You have a BN pleco in a 25 gallon. That fish on its own is going to mean continued water changes. This species is a poop machine. Personally I don’t keep adult 6 inch BN plecos in anything smaller than a 40 gallon. I do however have many juveniles in smaller tanks with multiple water changes each week.

Now add a school of 9 glow light tetras , 5 adult large snails , 5 shrimp and another catfish that all need feeding most days of the week and I believe you need to keep on top of the water changes.

I appreciate your advice, and I agree, which is why the test kit readings really confused me. I do have a pretty good filter on the tank, an eheim canister (150 which is meant to handle up to 40g of water, according to the box haha), and I think it's fairly well planted, but I didn't think that would be able to completely eliminate nitrate buildup. But the test I'm using is brand new, I don't see why there would be anything wrong with it.. and if the tests are reading true, then is there anything else the inhabitants are producing that I should be overtly concerned about?
To be perfectly honest I wouldn't mind getting some insight here actually, do you guys consider this heavily planted? I mean compared to dutch aquascapes this is nothing, so I don't really know what to consider this..

 

IMO, if you keep fish and or live plants you should do weekly water changes regardless if you water parameters are perfect or not.

Would you drink a glass of water that was sitting on your countertop for a week? Yeah I didn't think so.

 

Hormones that fish produce can’t be measured with our test kits.

Both fish and plants use minerals up that can only be replaced with a water change. On argument is fish food and fish waste will provide these minerals?

 

I consider that moderately planted. I’ve seen some heavily planted tanks that have more green than water haha. Do you plan to upgrade eventually? I agree with above, the bn won’t like a tank that small, totally missed that in the first post. I’m surprised the tank has 0 nitrates with that stocking lucky you lol. If you need to go a few extra days or even skip a week because things happen, you’ll be fine. Just I would do weekly as a normal schedule.

 

I just know from my own experience that doing weekly water changes has made a world of difference in my tanks. I believe it does keep everything more stable as a whole to have regenerated water every week. I have a BN in my 55g and she poops A TON. I couldn't imaging the deritus I would vacuum out of there in 2 weeks.

 

IMO, if you keep fish and or live plants you should do weekly water changes regardless if you water parameters are perfect or not.

Would you drink a glass of water that was sitting on your countertop for a week? Yeah I didn't think so.

I mean, that's certainly an interesting way of putting it, although I don't know that they're necessarily comparable circumstances haha. And I don't disagree, I just don't quite see how leaving the water changes for 3 or 4 more days would do much damage.

Hormones that fish produce can’t be measured with our test kits.

Both fish and plants use minerals up that can only be replaced with a water change. On argument is fish food and fish waste will provide these minerals?

I am aware of hormones and some of the effects that a buildup can have on the fish within your aquariums, ie. stunted growth and apparently increased aggression in shared betta tanks (sororities and divided tanks). Although I am curious the degree to which hormones are produced.. I mean it feels to be one of those things that are less commonly discussed in the hobby. I'd love to read some articles if you have any. Bioload quantity seems a lot easier for us to measure, which is why we know for instance that goldfish tend to be heavy producers, but I wonder if hormones function in the same way?
As far as water inherently containing minerals that fish lack that needs replenishing, I was wondering if topping water off + fertilizer could function as a temporary stand in between changes? For instance, if I were to do a 40% water change every 10 days, instead of 7, would a top off of 5% of the water every 5 days be enough to tide the tank over?

I consider that moderately planted. I’ve seen some heavily planted tanks that have more green than water haha. Do you plan to upgrade eventually? I agree with above, the bn won’t like a tank that small, totally missed that in the first post. I’m surprised the tank has 0 nitrates with that stocking lucky you lol. If you need to go a few extra days or even skip a week because things happen, you’ll be fine. Just I would do weekly as a normal schedule.

Thank you for your response! And I know, like I said, mine is nothing compared with tanks like that! I have a friend with a 150g that he could be rehomed to, but beyond that I don't have plans to upgrade right now. Tbh I'm a little surprised, I've seen polls on here before with quite a lot of people doing water changes only once or twice a month. I've always worried about not cleaning my tanks enough, so when I got these readings, I got to thinking perhaps I'd been doing water changes too frequently? And that maybe I ought not to have been as diligent with them as I have been?
But it seems I'd been doing things as I should, if the responses here are anything to go by haha.

 

I would consider that to be heavily planted.. I'm not overly surprised that you have low nitrates. BTW, unless I've missed something crucial here, a BN pleco is fine in a 25g tank. Yes, the maintenance is quite high, but that is a safe size for them. I would base a decision to rehome off of the maintenance, not necessarily off of space

 

Chances are if you go to a different forum or talk to different hobbyists you’ll get different answers. There’s no scientifically proven things to back up most of our fishkeeping suggestions. The only thing backing up our recommendation for weekly wc here is our own personal experiences. Many people will tell you the fish appear less stressed, they have less disease outbreaks, more frequent breeding behaviors, and more. As well as the fish keeper’s own peace of mind knowing the tank is well maintained. A weekly water change also makes sure you go and actually thoroughly check on your tank, which you might not otherwise do.

Edit: i guess I shouldn’t speak for everyone, someone may in fact have a research article supporting this!

 

Chances are if you go to a different forum or talk to different hobbyists you’ll get different answers. There’s no scientifically proven things to back up most of our fishkeeping suggestions. The only thing backing up our recommendation for weekly wc here is our own personal experiences. Many people will tell you the fish appear less stressed, they have less disease outbreaks, more frequent breeding behaviors, and more. As well as the fish keeper’s own peace of mind knowing the tank is well maintained. A weekly water change also makes sure you go and actually thoroughly check on your tank, which you might not otherwise do.

Edit: i guess I shouldn’t speak for everyone, someone may in fact have a research article supporting this!

Very well said! I totally agree.

 

I am a firm believer in big weekly water changes. I change no less than 50% of the water in each of my tanks each week. Occasionally I may go 8 or even 9 days between water changes but that is usually when I do my bigger than normal weekly water change.

I have to think this is the main reason I have never had to deal with any of the many diseases I read about here on a daily basis. The very best thing you can give your water pets is fresh clean water. Keeping the water clean prevents an invisible build up of TDS (total dissolved solids) and replenishes depleted minerals. In my humble opinion there is no downside to large weekly water changes.

 

Just over 43 years of having fish, and I can honestly say Ive never had a fish come down with any disease. Call me lucky? Sure, but when I play lotto I get maybe 1 number.
All my tanks through out the 43 years always had 1-2 water changes every week.
I now have 4 up and running and they all get a 40-50% water change on Wednesday, and a 75% water change every Saturday.
My oldest Angel fish was with me just over 14 years.

 

I very seldom do water changes as well, but I also only have like 5 small fish in a 100 gallon tank with lots of plants and filtration. I top off with r/o and do a 30% every 4 or so months with tap.
I have a 2g shrimp tank that gets a cup a day swapped out with only spring water. The heavier your stock the more frequently you need to do water changes. Estrogen kills.

 

The effects of growth hormones that fry produce are easy enough to witness any time you have dozens of live bearers. I don’t need a bit of writing on paper to guarantee the difference you will see between 100 fry in a small tank getting one water change per week and another 100 fry in the same tank getting 3 water changes each week. It’s not the nitrates that stops the smaller fry growing, it’s the growth inhibiting hormones used by the biggest fry . I was sceptical until I saw it for myself.


Pfrozen. Perhaps you did miss something?
It is only my personal opinion and what I want to see that stops me keeping 6 inch BN in any tank smaller than 40 gallon. I thought that was clear in my post on #14?

 

Chances are if you go to a different forum or talk to different hobbyists you’ll get different answers. There’s no scientifically proven things to back up most of our fishkeeping suggestions. The only thing backing up our recommendation for weekly wc here is our own personal experiences. Many people will tell you the fish appear less stressed, they have less disease outbreaks, more frequent breeding behaviors, and more. As well as the fish keeper’s own peace of mind knowing the tank is well maintained. A weekly water change also makes sure you go and actually thoroughly check on your tank, which you might not otherwise do.

Edit: i guess I shouldn’t speak for everyone, someone may in fact have a research article supporting this!

Very well said! I totally agree.

I am a firm believer in big weekly water changes. I change no less than 50% of the water in each of my tanks each week. Occasionally I may go 8 or even 9 days between water changes but that is usually when I do my bigger than normal weekly water change.

I have to think this is the main reason I have never had to deal with any of the many diseases I read about here on a daily basis. The very best thing you can give your water pets is fresh clean water. Keeping the water clean prevents an invisible build up of TDS (total dissolved solids) and replenishes depleted minerals. In my humble opinion there is no downside to large weekly water changes.

Thank you all for the advice you've provided and your recommendations! Looks like I'll be sticking with my regular schedule. I'll be keeping an eye on my numbers before each water change to see if this is a consistent thing, it seems odd for them to be consistently at 0.

The effects of growth hormones that fry produce are easy enough to witness any time you have dozens of live bearers. I don’t need a bit of writing on paper to guarantee the difference you will see between 100 fry in a small tank getting one water change per week and another 100 fry in the same tank getting 3 water changes each week. It’s not the nitrates that stops the smaller fry growing, it’s the growth inhibiting hormones used by the biggest fry . I was sceptical until I saw it for myself.


Pfrozen. Perhaps you did miss something?
It is only my personal opinion and what I want to see that stops me keeping 6 inch BN in any tank smaller than 40 gallon. I thought that was clear in my post on #14?

Oh I believe you! A teacher I had rescued a goldfish from a 6g, and put it in their 500g pond. The poor thing had been about 2in long for the whole 3 years it was in the tank, while it grew massive in her pond. I was honestly shocked it was still capable of growing any larger after so long stuck at a stunted size! Although I am curious about how these hormones effect fully grown adult fish? I'd love to see more studies published related to hormones and their effects on aquarium fish

 

This feels like one of those things that you're always aware of, but don't really think about at the time, if that makes sense haha? I guess I wasn't really thinking about anything beyond the scope of just my ammonia, nitrite and nitrates. I know of course that there are more factors involved with the quality of the water, but I guess what I'm asking is, if I were to leave a water change for a few more days than the 7 I normally do them at, would it be harmful to my tank? Would it effect anything either in the short-term or long-term that I'm unaware of? Could I get away with a water change at 2 weeks without anything bad happening?

I haven't done a water change on my 60 in three weeks, not on purpose though. Everything seems to be fine right now although I also haven't done any tests in those three wks either.

 

The effects of growth hormones that fry produce are easy enough to witness any time you have dozens of live bearers. I don’t need a bit of writing on paper to guarantee the difference you will see between 100 fry in a small tank getting one water change per week and another 100 fry in the same tank getting 3 water changes each week. It’s not the nitrates that stops the smaller fry growing, it’s the growth inhibiting hormones used by the biggest fry . I was sceptical until I saw it for myself.


Pfrozen. Perhaps you did miss something?
It is only my personal opinion and what I want to see that stops me keeping 6 inch BN in any tank smaller than 40 gallon. I thought that was clear in my post on #14?

Sorry mate, I missed your post. What I meant was, it is possible for the many breeds that only grow to 5 inches at most, but it requires a ton of maintenance and isn't something I would recommend to a beginner. I should have been more clear. If we differ in opinion it isn't by much.. a 40 would be far more appropriate

 

I agree with Stargirl and would also like to add that many other dissolved organic solids accumulate in our tanks that we don't test for. There's more to water chemistry than 0,0,0 and "good to go." For example, you could hang a bunch of pothos vines over a literal swamp hole filled with garbage and the nitrates would read 0 after awhile. Obtuse example but effective

Hormones that fish produce can’t be measured with our test kits.

Both fish and plants use minerals up that can only be replaced with a water change. On argument is fish food and fish waste will provide these minerals?

Agreed and not only about minerals, hormones and organics, our fish tanks are perfect environments for a whole host of microorganisms including pathogens which are present in much higher concentrations in our tanks than fish are exposed to in nature. After all, our fish are swimming in a soup of their own excretions. Regular water changes help to keep their numbers low so that they do not overwhelm the immune systems of our fish.

So it's not just about nitrates. Having said that, it's reasonable to consider stocking levels and potentially adjust accordingly. More is generally always better than less though, except for sensitive critters like shrimp.

 

You can definitely last a long time without water changes depending on what plants and bioload are in the tank.

Eventually the TDS will creep up and certain chemicals might build up. And if you are trimming plants then micronutrients will get depleted fast.