Water changes, opinions on how much and often.

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TMaier

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I have read 10% to 50% water changes. Weekly or less often.

If you have doubled your filtration can you decrease water change amounts and frequency?

Just curious, how do you figure out the right answers for your personal tank?


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Mostly depends on bioload and if your tank is planted. Filtration doesn't give new water, though. Water changes are the only way to do that. A good starting point would be 25% a week. High nitrates indicate a need for bigger or more frequent water changes.


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It's a good question on filtration. Thinking about it here, I guess extra filtration always helps but it's still a closed system until you do a water change. I must ask the local fish breeders around here - my impression is that water changes really help young fish but would be good club discussion.
 
Many would disagree, I'm from the school of the more water changes, the best your fish will be but a lot of it has to do with how much you feed them, how many fish and the type of fish.

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I guess I just keep testing to water. They are perfect. I hate to monkey with perfect just because of a schedule. But then I get paranoid and change 20% every 2 weeks.


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I change 30% weekly regardless of nitrate levels. Water changes also help to restore buffers and minerals in the water that your fish and biofilter need and I find that my fish seem to be more happy after. How big is your tank? If it's over 20 gallons I recommend getting a Python water changer I finally broke down and bought one about month ago and it's probably the best investment I have made.
 
Many would disagree, I'm from the school of the more water changes, the best your fish will be but a lot of it has to do with how much you feed them, how many fish and the type of fish.

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Sounds interesting? Where would they disagree.
 
Sounds interesting? Where would they disagree.

Where would they disagree? Perhaps that I'm not one to go by a certain percentage weekly or bi-weekly, in other words, I don't keep a tight schedule but I do change water often and lots of it at once. I might change 50% a week, sometimes I'll go a couple of weeks without a change and then do an 80% change.
Of course, using a garden hose to empty and refill the tanks makes it so much easier.
 
I change 30% weekly regardless of nitrate levels. Water changes also help to restore buffers and minerals in the water that your fish and biofilter need and I find that my fish seem to be more happy after. How big is your tank? If it's over 20 gallons I recommend getting a Python water changer I finally broke down and bought one about month ago and it's probably the best investment I have made.


I can change water and vacuum easily enough. It's not the labor or time. It's more the question of should I mess around with what seems to be good at the moment. I use DI water. So I wonder if it even has these buffers and minerals you speak of? ImageUploadedByAquarium Advice1464834285.535451.jpg


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It's a good question and in my honest opinion there is no real right or wrong answer except that you change some water at some point. The reason I say this is because it really depends on the tank in question. What are the parameters, what are the goals of the tank, do you have large fish, small fish, do you keep plants? If so you you overdose on nutrients and inject co2?

I have a friend that has an overstocked 180 litre aquarium with what would be termed as an inefficient filter flow. He does 20% water changes a week for nearly two years and has some of the best looking jungle val I have ever seen and has not lost a fish that wasn't down to tank mate incompatibility.

As a general rule 50% weekly water changes should be a good start, then you have to observe the tank and see what's what. If you want to keep plants and don't use ferts or co2 50% weekly water changes may impact on nutrient availability especially if you are understocked and underfeed.

I would tell a beginner no less than 20% water changes but then it is up to them after a time to come to their own conclusion.

I have kept tanks that do not receive water changes and some that do. Both ends of the spectrum. The ones that didn't receive water changes are the ones that had the most problems but then again there are other reasons that may have had an impact on that too. Decaying soil substrate producing ammonia and swallowing o2 for one.

Lots to ponder really but I think the benefits of water changes outweigh the negatives.


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+1 on the above. You have to be observant and know how to maintain a balance.
I also maintain what most would call overstocked and underfiltered tanks with fish thriving in them. In my case I rely mostly on water changes but even with optimal filtering, water changes are crucial.

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Water changing and water testing go hand-in-hand. A stable tank with a known good water source and established change schedule might not need much testing. I went years on my previous tank without so much as a single test. OTOH, new(er) tanks and systems undergoing major changes will need more frequent testing - to tell you what amount of water changing is called for. In this case, more is usually better. Everything else (feeding, nutrients, plants, whatever) is tweaking - to be tracked by testing.
 
I can change water and vacuum easily enough. It's not the labor or time. It's more the question of should I mess around with what seems to be good at the moment. I use DI water. So I wonder if it even has these buffers and minerals you speak of?

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Just wondering if that is pure rodi water into tank or a blend of rodi and tap (or other buffered water).
 
TDS hasn't been mentioned yet.
That is often the silent freshwater tank killer when frequent water changes are not done or if the tank is only topped off.
Fish can be kept with minimal WC's if the filtration/plants are sufficient to handle the bio-load
BUT
that still does not address the increase in total dissolved solids that creeps up, even more so whenever a tank is mainly just "topped off".
That probably accounts for many mystery tank crashes, as has been discussed here before at length.
The other possible issue with infrequent water changes is that if/when a substantial cleaning/change is needed, it can throw the fish into shock and kill them.
How often have we heard "everything's been fine for years and then I did a big WC and they all died"

The best course of action is at the very least monthly changes of ~20%.
Personally I go ~20% weekly for my salt tank and ~20% bi-weekly for the fresh.
But my little tank with a trigger and two eels gets a 90% change bi-weekly :eek:
(I feed them a lot :whistle:), but they are tough and can handle it...LOL

The main thing is to develop a habit/pattern that the fish tolerate and learn to expect.
That will vary depending on the type of fish and other specifics that only you will be able to sort out.
 
My 29 gallon tank has small fish and plants. No liquid frets or Co2. I watch how much I feed. I have a canister with 2x+ the flow needed and tons of bio filtration. My large substrate allows great vacuum capability. I use straight DI water. No tap water. We use a water meter to measure PPM to monitor water as well for those TDS concerns. If the PPM are highish I will change small amounts of water more frequently.

Khuli's are great indicator fish. If something isn't perfect or if PH swings they act up. They are one of the main reasons I do not over change the water.

I currently change 20% bi-weekly and so far so good. My plants are potted in glass pots in the tank in substrate with root tabs. And of course the Java and Anubis are pulling nutrients from the water.

I keep a close eye on everything but am always curious on what others are doing and why.


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I change about 25-30% weekly in both planted and shrimp tanks. I try to change the floss in the HOB filters 1-2 times a month. No gravel vacuuming. Minimal food given. I rarely do testing.
I recently picked up a TDS meter and now trying to get into the habit of monitoring it on my tanks on a regular basis. I want to be able to use it to assess the stability of the tank(s) and see how effective my water change schedule is.


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One other issue which wasn't mentioned is hormones. I understand that some fish give off hormones which stunt the growth of the other fish in the tank. This is alleviated with water changes.

Jack Wattley is a discus breeder who wrote a regular column for TFH Magazine. He once did an experiment where he raised baby discus in 2 identical 20 gallon tanks. One tank had filtration and had weekly 20% water changes. The other tank had no filtration and daily 90% water changes. At the end of the experiment, the unfiltered tank which had daily water changes had substantially larger and healthier fish.

I've been keeping fish for over 40 years. I perform 50% water changes every week on all of my tanks, and my fish seem happier and healthier.
 
My 29 gallon tank has small fish and plants. No liquid frets or Co2. I watch how much I feed. I have a canister with 2x+ the flow needed and tons of bio filtration. My large substrate allows great vacuum capability. I use straight DI water. No tap water. We use a water meter to measure PPM to monitor water as well for those TDS concerns. If the PPM are highish I will change small amounts of water more frequently.

Khuli's are great indicator fish. If something isn't perfect or if PH swings they act up. They are one of the main reasons I do not over change the water.

I currently change 20% bi-weekly and so far so good. My plants are potted in glass pots in the tank in substrate with root tabs. And of course the Java and Anubis are pulling nutrients from the water.

I keep a close eye on everything but am always curious on what others are doing and why.


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Out of interest do you need to remineralise the DI water as using it straight?
 
I use coral. I have several sizable pieces I keep soaking and I use that water if my tests reflect I need to add a bit of mineral. Only as a last result do I add dissolved mineralized salts in a slow flow. Don't want to hurt my snails.


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I use coral. I have several sizable pieces I keep soaking and I use that water if my tests reflect I need to add a bit of mineral. Only as a last result do I add dissolved mineralized salts in a slow flow. Don't want to hurt my snails.


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Thanks for the share.
 
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