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Water change 50% net or gross ?

eminor

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5 Feb 2021
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France
Hello, i see a lot 50% water change, my tank is 54l, 30l of real water, should i change 15 or ~25l then for Estimated index ? thx
 

Zeus.

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I go off depth of water, if 32cm to bottom of tank then 16cm is 50%. For EI dosing I use the calculated volume going off water depth x length x width of tank, ignoring substrate and hard scape
 

ceg4048

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Hello, i see a lot 50% water change, my tank is 54l, 30l of real water, should i change 15 or ~25l then for Estimated index ? thx
Hello,
Do whatever method is easiest. Everything are approximations and there is no penalty using whatever method you choose. That's why the word "Estimative" is used.

For changing water you can simply use the height of the tank. Again, this is about 50% but you are not constrained to this number. You can do 40% or 90% and anything in between. CO2 forces a higher metabolism in plants and so they produce a lot more organic waste, that if left unattended, can foul the water and can cause problems. The more water you change, the better because it dilutes the precursors to toxic compounds if present, such as ammonia or nitrite. To this end, removal of solid waste is also very important. Cleanliness of the tank is an important factor in success using ANY eutrophic dosing method.

Calculating dosing should be based on the tank size, simply because it is easiest. If the tank is filtered using a sump then the sump size should also be added to the size of the tank. Again, this is by far the easiest method and this is the method used to develop EI in the first place.

This is in stark contrast to dosing the aquarium with medicines, which are often toxic if dosed inappropriately.

Since the dry salts used in EI are non-toxic it does not matter whether you are above the target or even if you are somewhat below the target because the plants are still being fed several times more than they can actually uptake - for the vast majority of tanks.

Cheers,
 

ceg4048

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Another mind freed from the tyranny of The Matrix.

Take the Red Pill.jpg
 

MichaelJ

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thank you so much guys, i'm learning so much on this website, there is so much myth in this hobby, that's crazy, i always tought fertilizer caused algae until i've come here, i know now that's its a lie
Niels Bohr, the great Danish physicist, defined an Expert as a person who has found out, by his own painful experience, all the mistakes that one can make in a very narrow field. Heisenberg later on offered a slightly different, and perhaps better version, paraphrasing his advisor allegedly, and said an Expert is someone who knows some of the worst mistakes that can be made in his field, and how to avoid them.
Cheers,
Michael
 

Garuf

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I only recently had this thought after spending 15 years measuring out 50% of total system (including filter) and I’m glad to read someone else had the thought to ask.
 

LondonDragon

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I actually perform around 80% water change a week, sometimes twice! As once someone said to me; "doing a water change if like giving your fish a blood transfusion", haven't had any issues doing that, just crystal clear water all the time.
 

Cherries

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I actually perform around 80% water change a week, sometimes twice! As once someone said to me; "doing a water change if like giving your fish a blood transfusion", haven't had any issues doing that, just crystal clear water all the time.
I agree 100%! I do 80s myself, and someone said when doing such large water changes dilute out any potentially harmful microorganisms out of water. Buy I met someone that said such large water changes kill fish, so I see its quite a controversial topic. But I personally never had a problem with large water changes.
 

Garuf

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I’ve done whole system water changes when I’ve had co2 disasters and monitored the tanks after and had no detectable spikes to indicate that the biological aspect of the filtration has also crashed.
 

MichaelJ

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I agree 100%! I do 80s myself, and someone said when doing such large water changes dilute out any potentially harmful microorganisms out of water. Buy I met someone that said such large water changes kill fish, so I see its quite a controversial topic. But I personally never had a problem with large water changes.
@Cherries. Totally agree... And I get that, especially for high energy tanks and high stock tanks and other factors that plays into this. For my tanks, I would think of 80% as excessive - unless combatting an issue like algae or disease. There is also a measure of practicality that goes into all this. For instance, for my two tanks I have to carry buckets through the house... I am definitely teetering on the edge of what my better half appreciate, especially when I spill water on the floor :)

Cheers,
Michael
 

sparkyweasel

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Buy I met someone that said such large water changes kill fish, so I see its quite a controversial topic.
There's at least one way that can happen. If a tank hasn't had any proper water changes for a long time, perhaps if if you're trying to help some-one rescue a tank from neglect, a big change can be too much for the fish that have gradually adapted to the old water. It depends on the fish and the circumstances, so doesn't always happen. But with a badly neglected tank it can be safer to start with smaller water changes and build up.
But big, regular, frequent water changes are safe for any fish I've come across.
 

ceg4048

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@Cherries. Totally agree... And I get that, especially for high energy tanks and high stock tanks and other factors that plays into this. For my tanks, I would think of 80% as excessive - unless combatting an issue like algae or disease. There is also a measure of practicality that goes into all this. For instance, for my two tanks I have to carry buckets through the house... I am definitely teetering on the edge of what my better half appreciate, especially when I spill water on the floor :)
Wow, do people still use buckets in 21st century? Why not just get a 50 ft. hose and a cheap submersible pump to get the siphon started? Use a spring clamp to affix the hose to the glass (or a Shepard's crook to hang it over the glass). Then use the pump on the other end if the fill water is stored in a barrel, or connect the hose directly to the faucet if filling with tap water. Come on now people, the Sumerians figured these things out 5,000 years ago and then invented irrigation. :drowning:

Could also buy a Python, which uses faucet water to run and to accelerate the siphon, but this wastes a lot of water.
python1.jpg


I would have thought by now we would have developed the Star Trek Transporter, where we could just beam the water out of and into the tank. Very disappointing...:thumbdown:

Also, why would an 80% water change be excessive? If it's good for treating a disease or algae, wouldn't it also be good for preventing disease and algae? Owners of CO2 injected tanks take heed. The plants actually produce more toxic waste than the fish do. Their waste is primarily in the form of carbohydrates, including, amazingly, sugars. There is a symbiotic relationship between plants and bacteria. The plants actively farm certain types of aerobic bacteria by releasing these carbohydrates upon which these bacteria feed. As a result, the tank becomes flooded with the carbohydrates, which then rot causing a reduction of oxygen in the water column. CO2 Hobbyists will be surprised that their filters quickly become clogged with the nasty brown detritus, which is the result of the increased metabolism of the plants and is comprised of rotting carbohydrate products. Filters need to be cleaned more often, gravel needs to be vacuumed more often and water needs to be replaced more often. This is exactly how algae and pathogens are kept in check, and how the tank is prevented from choking itself.

Any fish living in a body of moving water gets a water change of thousands of gallons or even hundreds of thousands of gallons of water every second of every day. Clearly the fish don't consider it excessive. Keeping fish in their own polluted toilet water ultimately kills them by virtue of multiplication of toxins and pathogens as well as by reduction of oxygen.

Folks who talk about fish kills after changing water may easily have replaced the removed water with water high in chlorine without using dechlorinator, possibly or perhaps made some other similar error with the quality of the water being imported to the tank. Fish can also panic and injure themselves during the act of the water change, become ill and perish as a result of their injuries. There are a million ways to kill fish and to then blame it on one's favorite boogieman.

Cheers,
 

MichaelJ

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9 Feb 2021
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Location
Minnesota, USA
Wow, do people still use buckets in 21st century? Why not just get a 50 ft. hose and a cheap submersible pump to get the siphon started? Use a spring clamp to affix the hose to the glass (or a Shepard's crook to hang it over the glass). Then use the pump on the other end if the fill water is stored in a barrel, or connect the hose directly to the faucet if filling with tap water. Come on now people, the Sumerians figured these things out 5,000 years ago and then invented irrigation. :drowning:
Hi @ceg4048 I have thought about changing my setup for WC's for sure. The situation at my house is that I am doing all the prep in our laundry room and the tanks are installed on a different floor pretty far from the laundry room... Running a hose could possibly work - would have to be at least 150-200 ft (big house) ... I'll have to figure out a bigger WC prep container and a sizable pump that can move the water. Anyway, now that I've been yelled at (again), I'll see what I can do to keep up with the Sumerians :lol: (and btw.my wife like your idea... so it just might work).

I would have thought by now we would have developed the Star Trek Transporter, where we could just beam the water out of and into the tank. Very disappointing...:thumbdown:
Agreed - lets hope the Heisenberg compensator is just around the corner. :cool:

Also, why would an 80% water change be excessive? If it's good for treating a disease or algae, wouldn't it also be good for preventing disease and algae? Owners of CO2 injected tanks take heed.
Well, of course. I was being specific, as I mentioned, to my low-tech tanks... and excessive, implying there would be something undesirable or wrong about it, was not what I meant (unnecessary perhaps would have been a better word - again, specific to my tanks...). With a CO2 injected tanks I would be in line with a much larger percentage as plants are running at a much higher (x10) metabolic rate. I guess, we all have to find the balance where it works for the specifics of our tanks, factoring in CO2 usage, plant mass, stocking level etc. (and yes, the practically so we don't burn out), be it 40% or 90% or anything in-between, as you mentioned above.

Their waste is primarily in the form of carbohydrates, including, amazingly, sugars. There is a symbiotic relationship between plants and bacteria. The plants actively farm certain types of aerobic bacteria by releasing these carbohydrates upon which these bacteria feed. As a result, the tank becomes flooded with the carbohydrates, which then rot causing a reduction of oxygen in the water column.
The biochemistry aspects of this sounds suspiciously related to another thread on Ca/Mg Gluconate usage for water remineralization - could you take a look? would love to hear your take on what's going on.

Cheers,
Michael
 
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erwin123

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4 Mar 2021
Messages
253
Location
Singapore
I use a hose for water change as my tank is 5m away from the nearest water point. but if you can't use a hose, how about a container with tap (this one is 15 litres)

Use a ladder or something so that its above the tank, connect a small hose if necessary and open the tap.

jerry can.jpg
 

MichaelJ

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Joined
9 Feb 2021
Messages
620
Location
Minnesota, USA
I use a hose for water change as my tank is 5m away from the nearest water point. but if you can't use a hose, how about a container with tap (this one is 15 litres)

Use a ladder or something so that its above the tank, connect a small hose if necessary and open the tap.
Actually for transfer out of the tanks I do use a hose (and gravity) running out in our yard... for adding WC water to the tanks from 5-6 US Gallon buckets (~20 liters) I am using a 1.5 GPM (6 liters per minute) battery driven transfer pump - like this from Menards (large home improvement retailer in the midwestern US):
1631494703042.png



Cheers,
Michael
 
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