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Water cange percentages and Frequency

3K views 36 replies 14 participants last post by  IntotheWRX 
#1 ·
I have a +- 10 gallon planted tank in my office at work, high pressure CO2 and am dosing EI. Because of the way I'm situated (right across the hall from the men's room) it's much easier for me to do a small (10%-15%) daily water change than to do a weekly 50% change. I have a little Tupperware container that holds about a half gallon of water, for small water changes I scoop out a couple of containers full of water, dump them in the john and re-plenish, it takes me about 5 minutes. For a large water change I've got to drag in the big 5 gallon bucket, it's more hassle and also a bit more disruptive. If I do a small water change each morning before dosing my ferts, will it work out the same as doing a weekly 50% water change? Thanks.
 
#2 ·
your water change % and frequency will depend on your tank. If your tank has a good ratio of plants and the water is balanced, you may only need to change it twice a year. If you have less plants and your water gets funky quickly, you will have to change it more often. 50% weekly is about as much as you would need to change it. It helps put good stuff in your tank and take out bad stuff in your tank. look at your plants as if they are your doctor report. you are the PHD MD DR. tank master. use your understanding to determine how to prescribe the water change.

i would say a 50% water change every month would be a better place to start. changing the water too often will let the algae thrive off the sudden changes while your plants are always struggling to catch up and adapt to the new water parameters.
 
#11 ·
i would say a 50% water change every month would be a better place to start. changing the water too often will let the algae thrive off the sudden changes while your plants are always struggling to catch up and adapt to the new water parameters.

3 times you've recommended that the OP not do regular water changes. The first post clearly says he's using the EI method. Regular water changes (typically weekly) are a big part of the EI method. EI dosing with 50% water change a month is a recipe for disaster.

Plants don't have to struggle to catch up, or adapt to proper conditions and parameters.
 
#3 ·
I was asking more specifically because I am dosing EI ferts. With EI the reccommendation is a weekly 50% water change to prevent an excess buildup of nutrients because EI is designed to provide essentially an over abundance of nutrients so that they don't become the limiting factor in plant growth. My quesion is will it work out the same with EI doing the smaller daily water changes vs the large weekly change.
 
#7 ·
@IKSdrinker gave you good advice. Technically if you increasing your dosing somewhat you could probably get a way with more frequent water changes, but weekly is definitely the way to go with your tank. Also daily water changes will get old really fast and most don't keep up with it. If you could use a python at office that would make the water change a 5 minute process.
 
#8 · (Edited)
Changing 50% of the water once a week, the most nutrients can possibly build up is 2x whatever is dosed between water changes. This is assuming zero plant uptake.

Changing 30% of the water, the most that can build up is 3x the amounts dosed between water changes.

Changing 10% of the water every day, would essentially be like doing no water changes, and dosing 10% less than you're actually doing. There'd be an eventual ceiling where the concentration no longer increased, but it would be high.

So as far as regulating the nutrient build up, this is not a good plan in conjunction with EI. There would be a never ending rise in nutrients.

Small frequent water changes do have their advantage. A constant supply of fresh new water is good for the whole system. Plants and fish love it. Algae hates it.

I remember an old thread on Barr Report talking about if you do a 10% water change every day you'll never have bba. Dont think enough people tried it out to really put the theory to the test, but it had some merit imo. Digressing a little...

If 10-15% daily water change is the only option, then you should find a dosing routine that pretty much targets what the plants actually use, or just a tad above.

How much the plants use will depend on your individual set up. How many plants and what kind, how much light intensity - that sort of thing.

You'll have to play it by ear for a while to find the sweet spot. if I had to guess, something like 1/4 EI 2x week might be a good place to start.

Then keep an eye on nitrate and/or phosphate levels as a proxy for what the tank is actually using. I say these two because they are easy to test for.

Test maybe once a week for a few weeks. If the levels continue to climb, reduce the dosing. If the levels get too low, increase the dosing.

Somebody else may have a better solution for you. But that's the only way I can think of to run a "high tech" tank with that kind of WC routine.

You may want to look into pps-pro dosing. It does sort of the same thing, but there are still water changes involved at certain times. I believe when TDS reaches a certain point, which has never made logical sense to me, but you may find some of the theory useful to apply in your case.


TL;DR - Find a way to do weekly 50% water changes :)
 
#9 ·
Changing 50% of the water once a week, the most nutrients can possibly build up is 2x whatever is dosed between water changes. This is assuming zero plant uptake.

Changing 30% of the water, the most that can build up is 3x the amounts dosed between water changes.

Changing 10% of the water every day, would essentially be like doing no water changes, and dosing 10% less than you're actually doing.

So as far as regulating the nutrient build up, this is not a good plan in conjunction with EI. There would be a never ending rise in nutrients.

Small frequent water changes do have their advantage. A constant supply of fresh new water is good for the whole system. Plants and fish love it. Algae hates it.

I remember an old thread on Barr Report talking about if you do a 10% water change every day you'll never have bba. Dont think enough people tried it out to really put the theory to the test, but it had some merit imo. Digressing a little...

If 10-15% daily water change is the only option, then you should find a dosing routine that pretty much targets what the plants use, or just a tad above.

How much the plants use will depend on your individual set up. How many plants and what kind, how much light intensity - that sort of thing.

You'll have to play it by ear for a while to find the sweet spot. if I had to guess, something like 1/4 EI 2x week might be a good place to start.

Then keep an eye on nitrate and/or phosphate levels as a proxy for what the tank is actually using. I say these two because they are easy to test for.

Test maybe once a week for a few weeks. If the levels continue to climb, reduce the dosing. If the levels get too low, increase the dosing.

Somebody else may have a better solution for you. But that's the only way I can think of to run a "high tech" tank with that kind of WC routine.

Also you may want to look into pps-pro dosing. It does sort of the same thing, but there are still water changes involved at certain times. I believe when TDS reaches a certain point, which has never made logical sense to me, but you may find some of the theory useful to apply in your case.


TL;DR - Find a way to do weekly 50% water changes :)

Thanks,

I can do the 50% once weekly, it's just a real PITA. I'll stick with it
 
#12 ·
My favorite way to keep my tanks is to just dose twice immediately after a large water change every week. Macros immediately after the change and then micros in the morning the next day. That's it for the week. I dose far less than EI levels (about 1/3 - 1/2 the amount) because I really don't think you need that much unless you are running on full blast.

Larger water changes are preferred by a lot of people who keep higher tech tanks and have to dose all the time. Like burr said the larger changes help to 'reset' your fert levels so you can't have a crazy buildup of nutrients over time if you are dosing more than you should. You can dose more liberally and still avoid having high levels because they don't have much time to build up before you cut everything in half (50% change). A leaner, more regimented approach is more appropriate for smaller water changes which is a PITA so many people don't do it that way.

If you take the super-low-tech road you can create a very balanced tank that does not need frequent water changes like IntotheWRX said. In a higher tech setup with higher light, CO2, ferts, etc this is not feasible IMO. I'm personally a strong proponent of doing water changes at least once a month regardless though.

I feel you with not wanting a sheetrock bucket for water changes at work lol. I used to have a nano tank at my desk and considered a 10g before setting it up. The main reason I didn't was the hassle of changing that much water in the office lol.

I do 50% changes on my 10g hospital tank sitting on the floor at home. I use a larger-sized tupperware container and a sheetrock bucket. Only tanks like 15 minutes to scoop 5g out into the sheetrock bucket, refill in the tub, and scoop the water back in. I would recommend this as a good option for you if you decide to do the 50% per week.

Having a high tech 10g tank with CO2 at work is awesome though! Good for you
 
#24 · (Edited)
I had thought about doing this but, my understanding is Fe and some other micros might not stay available from one day to the next. So, macros once a week after water change should work but, Fe (micros) might still need daily or every other day dosing. So, I just continue with PPS Pro, dose both daily. PPS Pro doesn't require 50 % water changes but I do them anyway.

If Fe would be available for a week, I would be with you. I would stop making solutions and dose powders once a week.
 
#14 ·
There's no glory in balancing a tank. It usually means you are putting in plants you might not want, reducing your light, reducing your fish load, etc. You have to find a narrow range that would work. When you change water on a regular basis you increase the range a tank can be run whether it's with less plants, more light, more stock. Gives you more freedom for the tank to look the way you want.

@IntotheWRX

I've seen you give your no water change advise in thread after thread regardless of whether the OP was using EI, Aquasoil, high-light, etc. I've also seen you flame people and leave perverted posts in various threads (including one of mine) which was removed by the moderators.

Your tank journal is a poster thread for why water changes are good. You started a tank with Aquasoil threw fish in within a week and most jumped out to escape the toxic conditions. You then started getting BBA and figured you would raise the co2 to I think 10 BPS in which you gased a bunch of fish. For some reason every time a fish died you had the urge to make a joke about it. Your now (last post are saw) down to like 4 hrs of light and dosing excel constantly to fight the BBA. That is not a balanced tank, not even close. So your doing all this and going around stating water changes are a waste of water, yeah right.
 
#21 ·
Yes, i am crazy. I do a lot of weird things. Im not like the normal fish tanker. I don't really take the advice from the forums as facts and leave more room for myself to explore. for example, i turned my bbps from 1 to 5 to test how the plants and fish and bubbles would react. I did it for maybe 5 minutes until I saw some reaction on the plants, like harder pearling.

Have you seen the myth busters? I come from the same mentality. WE TAKE IT TO THE LIMIT. test test test. my first couple months of aquariums has been a lot of testing. pushing things to the limit. im always glad to share my experience with you guys. but please dont judge me.

bashing on my 4 hour light period? What is 4 hour to you? 4 hour to me is the time I come home from work and a time I set for myself to go back to the bedroom to start sleeping. This is my life. don't judge my photo period.

make them say ughhhhh, no limits.
https://www.youtube.com/watch?v=2MgDVZeAQK8
 
#15 ·
Common sense tells it's better to do small changes more often. It's better to clean toilet a little every day instead of waiting whole week for large cleaning, correct?

Let's try to prove it. Here is math.
b - is the amount of daily changes (10%, for example) 0<b<1
a - coefficient of daily water "freshness", i.e. a=1 - water stays fresh all the time, a=0.2 - means if 100% fresh water is added, then it'll be only 20% fresh next day. This coefficient is measure of kaka buildup, etc,
0<a<1

One can write geometrical progression to calculate "freshness" of water ever day. Kinda simple (9 grade?) but I will omit it (drop me a line if you really want to know). Assuming we start from "dirty" water (freshness=0). Then, after the Nth change:

F=b* (1 - (1-b)^N*a^N) /( 1- (1-b)*a)

If we do changes every day, then after long run freshness:

F=b/(1-(1-b)/a)

10% daily changes (b=0.1) and 90% freshness coeff (a=0.9) in a long run, water will be 0.52 fresh constantly.

If we replace 50% once a week, then (a=0.9 as above) water freshness goes from 0.5 (after changing) to 0.27 before next change. Which is significantly worse than 0.52.

You can play yourself with numbers in Excel


This game of numbers is simply to illustrate small frequent changes is better:

1) Environment is cleaner.
2) Environment is more stable. For example less swing in pH, etc. Of course, sometimes it's needed, for example, to induce fish spawning
 
#17 ·
Common sense tells it's better to do small changes more often. It's better to clean toilet a little every day instead of waiting whole week for large cleaning, correct?
Yes but one might get tired of cleaning their toilet bowl everyday and then stop doing it completely and then everything gets really nasty. Unless you have automatic water changer and large fish load (usually not a problem in planted tanks) daily water changes just aren't going to work from a realistic husbandry standpoint.

As @burr740 pointed out there is a nutrient dynamic at the center of someone dosing EI and water changes. The idea behind EI from what I understand is to create an easy to do dosing routine that provides the plants what they need by keeping all their nutrients available within given ranges and eliminates the need for regular testing. Once a week is realistic long-term, daily is really not.
 
#18 ·
I think saying EI is a bit nebulous because it doesn't dictate whether you go rich or lean. The real idea is to start out with more than needed, back it down slowly until you notice deficiency, then bump it back up a bit and adjust as needed - hence the estimative part. I think the higher tech tank you have, the more rich you tend to run which requires the larger changes.

I too was doing EI in my work tank, but with the several hundred foot journey to get water or dump water, I decided to break it into two days - Monday and Thursday. I dose macro right after wc, micro next day, then no dose until next wc.

I'm four months in on medium light with no CO2, and things have been doing just as well as they did before. To be fair though, it did take me a couple of months to dial my ferts back in to fit the new schedule.

Maybe it will eventually build up because I'm not changing out 50% at a time, but I'm betting that will be a very long time and could easily be fixed by doing a 50% or larger change once every few months or something.

Sent from my Nexus 6 using Tapatalk
 
#19 ·
Do what is convenient for you redchaser. If 10-15% works for you then do 10-15%.

IF you would like 10% water changes AND keep the same EI levels as you would with a 50% weekly water change THEN all you need to do is divide your current dosages by 5. For example, if you are currently dosing 20 ppm NO3 total each week with a 50% water change then you can now dose 4 ppm NO3 total (20 / 5 = 4) with daily 10% water changes. Over time, in both scenarios, you will end up with a maximum of 40 ppm NO3 in the tank if none of it is ever consumed by the plants.
 
#33 · (Edited)
This is the third thread on the merits of water changes vs no water changes and the notion of balance, in my opinion, is unattainable unless your plants are plastic and your fish do not grow, and your feeding schedule and selection remains constant. Any change in one variable has an affect on other variables that were thought to be static and then once that constant turns into a variable, it affects other variables. I believe what biologists call feedback. Positive feedback is awesome but most aquariums suffer negative feedback, which in my case is always self inflicted.

Maintenance, including water changes, is usually the simplest way to restore balance because it gets you back quickly to a state prior to when things went south, sort of like a restore on Windows 7 after that stupid Windows 10 upgrade.

Maintenance is preferred for most hobbyists because we don't want to remove the new fish we added, or rip out our favorite plant that started growing like a weed, since both the new fish and growing plant leads to an imbalance.

My solution happened not to be maintenance because my maintenance was good prior to the imbalance. Instead, I cut out all ferts and supplements in order to simplify. Once the system returned to balance, I started dosing again but at a much lower rate then before. If the system does not stay balanced this time, then I will either dose even less or restart water changes. Keeping an aquarium in perfect balance by keeping both plants and fish as static as possible is doable, but what fun is that.

The point is to savor the time between meltdowns.
 
#34 ·
Too sit here and say someone's formula is garbage without offering anything but negativity to this thread is the only garbage I see. If I could reach the switch on your surge protector, I'd surely flip it off.

OP, don't be afraid to try something new or "wrong" because that's exactly how progress is made. Leave the bucket at home and switch out a big gulp cup a day. Just realize this totally throws the EI method away and you should cut back on your ferts. I would just skip dosing one full week once a month.

Who feeds your fish when your not at work?
 
#35 ·
You might want to re-read the 1st post. The OP was asking a very specific question about more frequent, smaller water changes USING THE EI METHOD. IntotheWRX immediately gave him advice on water changes that could cause the OP serious issues with his tank. He also gave out CO2 advice that could easily kill all your livestock if followed. When I questioned some of his advice his reply completely contradicted some of his earlier statements.

The formula is based on a "coefficient of water freshness". When you make stuff up, and base a mathematical formula on it, the results are not always optimum.

This is not the first thread that this is happening in.

Experimentation is great. Going against things that have already been proven is ignorant. I have a tank that I have not done water changes for several months, but I have also stopped dosing.
 
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