The Planted Tank Forum banner

Opinion: How many water changes are necessary - it depends

10023 58
Once in a while, I see discussions about the importance of water changes with users taking different positions and arguing about how much water change is adequate. I try to take a step-by-step differentiated perspective and hope this might be useful for some of you. This is obviously my opinion and I might have misrepresented some approaches. My main point as you see at the end is that under the appropriate circumstances, you can get away with very few water changes which saves much time.

After receiving some feedback, I would like to add that level of experience is a factor to consider. For a newbie, it might be better to do more frequent water changes within the categories listed below to be on the safe side. More frequent water changes with good water quality do certainly not harm.

What is the purpose of a water change?
-Reduce the concentration of compounds that become harmful for the inhabitants of the tank

When are frequent changes necessary?

1.In tanks with high fishload or fish-only tanks
Waste products that end up become nitrites and nitrates accumulate and nothing removes it. Therefore, there is no way around regular water changes and I think that this is not a point of disagreement

2.Planted tanks with EI dosing (for planted tanks with little or higher fish load).
By regularly adding more ferts than the plants can use, ferts accumulate over time to harmful levels without compensating water changes. The maximum level of ferts that could be reached with EI is twice the amount of ferts added between 50% water changes, i.e. half of the ferts remain in the tank and you add the other half again until the next water change. Obviously the actual level is below that hypothetical maximum level due to the plant uptake.

When are less water changes necessary? (for heavily planted tanks with little fish load)

-If you have root feed or have something like a non-depleted ADA AS, and add hard water to compensate for water loss, some minerals accumulate over time which have to be removed by water changes. The frequency very much depends on your water quality and what mineral level you want to tolerate.

When are minimal water changes necessary? (for heavily planted tanks with little fish load)

-The least amount of water changes are needed if you compensate water loss with RO water and you use moderate water column fertilization or root feeding. The water column fertilization should be not higher than the plants can take up. This works best in combination with fertilization in the soil. The amount of added minerals through the additional water is minimal. In this situation, you can get away with changing water once a year or even less, because nothing harmful accumulates quickly. I understand that such long intervals are probably the most controversial perspective, so I provide some support below.

Low water change case:
I root feed with Osmocote+ and add not more than every other week 5ppm NO3 and 1.5ppm PO4. Occasionally, I add 0.01ppm CSM+B if signs of Fe deficiency become prominent.

I keep small sized fish such as Otocinclus, lambchop Rasbora (Trigonostigma espei) and Golden Pencilfish (Nannostomus beckfordi) and some Endler guppies. My last pencilfish of a group of ten died a few weeks ago, after having them for more than 5 years. I cannot remember how long I have the Rasboras. None of them died in the last 2 years. The Otos are also more than 2 years in my tank. In addition, I have more than 100 deep red cherry shrimp and some Amanos.

I keep more than 40 plant species in my 90 gallon tank with high light and CO2 and spend about 1 to 2h per week on my tank. Plants include

Ammania pedicellata
Ammania gracilis
Barclaya longifolia “red”
Blyxa japonica
Blyxa aubertii
Cabomba furcata
Cuphea anagalloidea
Eriocaulon setaceum
Glossostigma elatinoides
Hyptis lorentziana
Ludwigia senegalensis
Ludwigia hybrid “Atlantis”
Ludwigia inclinata verticillata “Cuba”
Ludwigia inclinata verticillata “Pantanal
Micranthemum tweedei “Monte Carlo”
Pogostemon erectus
Rotala indica
Rotala sp “red”
Rotala “mini butterfly”
Rotala “green”
Rotala wallichi
Staurogyne repens
Staurogyne “Porto Velho”
Syngonanthus “Belem”
Syngonantuhs “Manaus”
Syngonanthus “Rio ***** Giant”

The only problem with low water changes is that I have solid waste products accumulate in the soil. Therefore, I occasionally vacuum them into a large bucket with a cotton bag filter and pump the water back into the tank with a little pond pump. I do this because it is difficult to accumulate so much RO water for the water change and one of my main goals is to make the maintenance of the tank as much time efficient as possible while still maintaining a nice densely planted tank. This accumulation might lead to some dissolved organics that might lead to a low level of BBA in my tank. Purigen added to my canister filter seems to help to counter these effects especially after stirring up the soil during major replanting and vacuum events. BBA only shows on very old leaves and stems and is not really noticeable when in front of the tank.

I attach some tank shots to give you an idea how well this works for me.

Attachments

1 - 20 of 59 Posts

·
Registered
Joined
·
172 Posts
I really enjoyed reading this tank and found your approach and reasoning very logical.

I'm running a 29 (much much smaller) with moderate planting and very low bio-load. 6 Oto cats and a tiny colony of Neo shrimp, and have found that most of my screw ups are from water changes.

Good read and beautiful tank.
 
  • Like
Reactions: deepgreen1

·
Registered
Joined
·
32 Posts
Discussion Starter · #3 ·
Thank you for your feedback. I do not think that water changes are bad in principle, but it is usually much effort which might not be always necessary. I am not sure what could lead to negative effects of water changes. Too much chlorine may be or potentially some contaminants like too much copper?
 

·
Registered
Joined
·
1,131 Posts
Everyone knows I keep a wild jungle, lol.
125 gal. Real wood, real rocks and some fakes for hiding. Easy plants, no strict ferts added. DIY root tabs added 2x a year. Liquid Leaf Zone & custom blend added when I remember, 1-2x a month or so. Lights match the sun, so in winter, minimal hours and summer hours are long, on a timer I adjust as the sun changes. Water changes every 2-5mo, 75%. We are on well water & I made an attachment for my kitchen faucet so I can refill at the same temp. Made HOB drain attachments as well, so everything is as easy as possible for me. Husband wouldn't let me drill holes and make it all automatic. =(
FX5 & FX6 canisters cleaned every 3mo, alternate them. Well water, so easy to clean them, but heavy and hard to move filters. I fill them so restart is instant and do not use the drains because I don't want it to fail from over use or loose. Don't need more flooding...lol.
Tank is for my Miss BGK, her tankmates are 5 angelfish, young common Pleco, 2 Clown plecos, family of 4-5 BN plecos, family of 5-6 Emerald Green Cory, 2 very old Flagfish females and w/e snails that manage to live w/o BGK eating them.
I try to sell plants for cheap in spring and autumn, to tame the jungle some. No muck to vacuum off the bottom.
Levels always read perfect.
My koi pond is similar. 3.5k gallons(expansion to 10k soon to come), 3 fantail, 1 shubunkin, 9 or 10 koi. Heavily planted along the sides + floaters, bog heavily planted, 50g & 30g DIY filters that go to bog, perfect parameters. I try to w/c as much as possible, but well pump is screwy now and limits me to 500g at a time. No algae when shade is up. Lots of muck to clean out the filters and fine particles to finely floss out.
I would be lost w/o my plants.


Totally possible to have very few water changes.
 

·
Registered
Joined
·
1,415 Posts
I think people tend to get a bit dramatic when advocating weekly water changes. I always try to speak from experience rather than make generalizations. I think your post sums up nicely that it is not always so cut and dry.

I often see people in FB groups or forums telling newbies "Your fish will die if you do not do weekly water changes." But when my life has been crazy I have gone many many months without water changes and many fish that people would consider sensitive have survived for long periods with very high nitrates. It is not ideal and I definitely recommend regular water changes but with the amount of tanks I have, the other stuff going on in my life, and my general laziness level I know that for me every two weeks is more likely than every week and sometimes it might be more like once a month.

One thing I will say from experience is do not add new fish if your tank has gone a long time without a water change and you know your nitrates are very high. Your existing fish will have adjusted to the buildup of nitrate over time. For a new fish it will be a shock that could do them in.
 

·
Banned
Joined
·
5,942 Posts
When are frequent changes necessary?

The biggest reason not on your list is when you are new to the hobby and your not sure about how your tank will react to buildup of ferts and/organic waste.

Your not going to go wrong by doing regular weekly water changes, but you could go very wrong by not doing them. Water changes are preventive in many cases not necessary all the time. I'd rather prevent a problem before it starts then deal with it after it's happened.

Once your in the hobby for a while you could "read" your setup better and decide what's necessary, but for a newbie coming in the water change is a "Magic Bullet"
 

·
Registered
Joined
·
373 Posts
I think people tend to get a bit dramatic when advocating weekly water changes. I always try to speak from experience rather than make generalizations. I think your post sums up nicely that it is not always so cut and dry.

I often see people in FB groups or forums telling newbies "Your fish will die if you do not do weekly water changes." But when my life has been crazy I have gone many many months without water changes and many fish that people would consider sensitive have survived for long periods with very high nitrates. It is not ideal and I definitely recommend regular water changes but with the amount of tanks I have, the other stuff going on in my life, and my general laziness level I know that for me every two weeks is more likely than every week and sometimes it might be more like once a month.

One thing I will say from experience is do not add new fish if your tank has gone a long time without a water change and you know your nitrates are very high. Your existing fish will have adjusted to the buildup of nitrate over time. For a new fish it will be a shock that could do them in.
I think that mainly comes from advice given out to beginner tanks that people put goldfish in. Goldfish produce a ton of waste so nitrates can build up very fast. Rather than tell people to monitor their waste levels, a simple rule of thumb would be changing water every week. If you're a bit more advanced and using proper filtration and live plants you won't have any issues since the plants absorb nitrates so those levels don't really build up.
 

·
Registered
Joined
·
745 Posts
When are frequent changes necessary?

The biggest reason not on your list is when you are new to the hobby and your not sure about how your tank will react to buildup of ferts and/organic waste.

Your not going to go wrong by doing regular weekly water changes, but you could go very wrong by not doing them. Water changes are preventive in many cases not necessary all the time. I'd rather prevent a problem before it starts then deal with it after it's happened.

Once your in the hobby for a while you could "read" your setup better and decide what's necessary, but for a newbie coming in the water change is a "Magic Bullet"
Yeah, I would add this to the list too. When you are just getting into the hobby it's best to start with weekly 30-40% water changes to be safe. Later you can start to variate. Actually when I'm starting a new tank I'm doing weekly 30-40% water changes too and after I see how the tank is going I'm changing it. Summarizing I would recommend frequent water changes on every new setup and only after some time I would go down (even if you had 50 tanks before).
When I was fertilizing my tank lightly I was doing water changes once 2-3 weeks and only 10-15%, but to do that you need knowledge and deep understanding of your tank.
 

·
Registered
Joined
·
32 Posts
Discussion Starter · #10 ·
I have to ask if you aren't doing water changes what are you spending 1-2 hours a week on? I am just curious

Sent from my SM-G935V using Tapatalk
It is primarily trimming and replanting. I have to constantly make sure that I do not loose plants due to overgrowth. If I am lazy, I just cut the tips and trash them. This is the fastest, but I also have to be careful not to trim too low. I could lower the number of stem plants and have more forground plants, but then the temptation to get new plants takes over LOL.
 

·
Registered
Joined
·
32 Posts
Discussion Starter · #11 · (Edited)
When are frequent changes necessary?

The biggest reason not on your list is when you are new to the hobby and your not sure about how your tank will react to buildup of ferts and/organic waste.

Your not going to go wrong by doing regular weekly water changes, but you could go very wrong by not doing them. Water changes are preventive in many cases not necessary all the time. I'd rather prevent a problem before it starts then deal with it after it's happened.

Once your in the hobby for a while you could "read" your setup better and decide what's necessary, but for a newbie coming in the water change is a "Magic Bullet"
I agree that doing water changes more frequently does not harm and it might help prevent problems for newbies. My list is certainly not exhaustive. My point is more about the differences in approaches and the involved work. There are certainly other advises one can give. I would consider it even more important to put as many cheap plants in a beginner tank as possible with less frequent water changes rather than having a few lonely plants with many water changes. It all depends on the approach.

But I take your point and that of user nel that level of experience should be added.
 

·
Banned
Joined
·
5,942 Posts
.. I would consider it even more important to put as many cheap plants in a beginner tank as possible with less frequent water changes rather than having a few lonely plants with many water changes. It all depends on the approach.

But I take your point ant that of user nel that level of experience should be added.
But you see that's the point about water changes. Your aren't as restricted. Your suggesting putting in cheap plants to increase uptake and purify the water and I don't disagree, but what if you don't want that? There are many sides and styles to the hobby. Dutch style, Forest, Iwagumi, Minimalists many don't involve a tank full of plants buy doing water changes you have the flexibility to plant the way you want to. You also can drive light further for tough carpeting plants when you don't have a tank full of stems.

As you say it depends on your approach, but regardless of the approach the water change is always going to help the reverse can not be said for not doing them.
 

·
Registered
Joined
·
32 Posts
Discussion Starter · #13 ·
As you say it depends on your approach, but regardless of the approach the water change is always going to help the reverse can not be said for not doing them.
I do not say that there is no benefit of water changes, but that there are conditions where frequent water changes are not necessarily needed.
 

·
Banned
Joined
·
5,942 Posts
I do not say that there is no benefit of water changes, but that there are conditions where frequent water changes are not necessarily needed.
I didn't say you said that (where did I say that?), what I am saying is a water change is beneficial to every type of setup whether it needs the change or not. The reverse is NOT true, so when you don't know it's better to do the change. It's the difference between something being preventive (like a vaccine) vs treating a disease with medication after it occurs.

BTW a water change is probably one of the easiest, quickest things to do and the benefits are enormous. It's literally a 10 minute procedure with a python for most tanks.
 

·
Registered
Joined
·
32 Posts
Discussion Starter · #15 ·
what I am saying is a water change is beneficial to every type of setup whether it needs the change or not. The reverse is NOT true, so when you don't know it's better to do the change. It's the difference between something being preventive (like a vaccine) vs treating a disease with medication after it occurs.
At this point, I usually ask where is the evidence. The beneficial effects of vaccines have been demonstrated by many controlled scientific studies. I have not seen anybody demonstrating that in the conditions of my last example with low need for water changes that a water change is beneficial. Just because something is not harmful does not mean it is beneficial. I provided evidence that despite very low frequency of water changes, my tank has thriving plants, healthy fish and shrimp. I even have some freshwater annelids that have been introduced about 10 years ago.

When your water quality is low, a water change is no longer that simple or cheap in the long run as you need to add water conditioners or RO waters because not every inhabitant of a tank is happy with high chlorine or nitrate levels, different metal ions, or high KH. In addition, not everybody has hoses setup for their tanks anyway. So, it is not always as easy as you say.

What harmful compounds should accumulate in a highly planted tank with RO water and low fish load? Even with high KH it takes some time to increase KH levels depending on your evaporation. I understand your point that you would like to extend the safety line, but I would like to draw a line where it becomes a waste of time and who has time to waste?
 

·
Banned
Joined
·
5,942 Posts
@deepgreen1

For some reason you keep missing the whole point. It's not about YOUR tank not needing regular or larger water changes it's about using regular water changes as a universal preventative measure for anyone's tank, especially someone not knowing what bandwidth they could work with. I'm talking about any tank, any parameter will benefit from a water change. You don't need a tank full of plants like you have to counter. Not everyone wants that.

If you don't have 10 minutes to do a water change, I would recommend a different hobby. A water change is one of the easiest things you could possibly do. How bout you take 3/4 of your plants out and double the light intensity. Let's see if you can get by without more water changes. That's the limitation to a setup that doesn't get regular water changes. You need heavily plant mass and/or lower light with a limited number of plant types.
 
1 - 20 of 59 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top