Do you consider a water change to be an effective type of aquarium filtration method?

[pledosophy]

It depends on what you are doing and what you hope to accomplish.

Math tells us:

1. You can not keep a tank at proper levels long term with water changes where the new water is at sea levels.

2. You can also not remove pollution long term using water changes.


They are effective for some things, and as part of a filter strategy, in some cases but not others. Tank size also matters. Doing a 50% change on a 10g tank with nitrates at 100 is probably the easiest option. For a 1000g tank, there are better options. That is why we see such huge contrasts in peoples experiences.

When I was breeding fish, a 50-100% daily water change was sometimes necessary. If there is a problem in a tank that needs correction a large water change is great. A weekly 10% change may help people who are not keeping levels appropriately if there livestock is low need and they use replacement water at elevated sea levels.

So a complete answer to the question, like many things in this hobby is it really depends on the situation.

 

[gbru316]

No.

noun

1. a porous device for removing impurities or solid particles from a liquid or gas passed through it.
   "an oil filter"
2. 
   BRITISH
   an arrangement whereby vehicles may turn left (or right) while other traffic waiting to go straight ahead or turn right (or left) is stopped by a red light.
   "a filter lane"

verb

1. pass (a liquid, gas, light, or sound) through a device to remove unwanted material.
   "the patient is hooked up to a dialysis machine twice a week to filter out the cholesterol in the blood"

Water changes do not fit any of these definitions.


Water changes are part of a nutrient/element management strategy. They are not filtration.

 

[pledosophy]

For most people, it's more a matter of replacing elements than filtration. I haven't done a WC in 8 months and couldn't be happier (my corals too). Reef Moonshiner here.

If you keep up with the Reef Moonshiners you will have to add salt in time. I did a similar program and came to the point where I was doing small water changes once a month. Those type of changes have a specific name, they call it "fragging". All those little bags full of water can add up

 

[rtparty]

The only way a water change is effective at controlling N and P is if you are doing large enough water changes to stay ahead of your import. Export must be greater than import or it doesn't work.

On a 250g tank, 50% water changes are never happening regularly. 10g nano? I can do 4g a week no problem.

Water changes are misunderstood, overused, and bandaids for most. They do have merit but not nearly what has been claimed over the years

 

[Jay Hemdal]

Are you quoting Anthony Calfo or was he quoting you?

I’m quoting my college chemistry prof from the 1970’s (grin). I think it’s a very old saying ……
Jay

 

[ChattReefer]

The difficulty I have with calling this is form of "Filtration" on anything bigger than a 20g nano, is that many of us keep larger tanks (100g+) and I have a suspicion we are not regularly doing 25% water changes weekly on our 100g+ systems. So let's bring it down to a 10% water change weekly. That's going to leave 90% of the dirty, depleted water in the tank (this is saying water change as filtration, I'm not including socks, Refugium, Algae Scrubber, Skimmer, or any other forms of Filtration).

On a nano tank where it is not being filtered through a sump with tons of mechanical filtration, a 25%-50% Water Change could make sense as a form of Filtration in the aquarium.

That's my opinion and nothing more! Would love to see more data on the amount of trace elements are taken up / replenished with weekly water changes.

 

[Montiman]

Personally, I would not call water changes filtration. My car has an oil filter but also gets oil changes. I would not put them in the same category.

This thread has been going down the rabbit hole of a broader discussion about water changes so I thought I would make a comment.

Deciding to do water changes or not do water changes on principle is terrible. It is best to look at your tank list your goals and consider what is the best way to reach them.

It is true that water changes are a poor way of removing dissolved organic compounds if the goal is extremely low levels. For example, if I have a PO4 of .5ppm it will be very difficult for me to achieve .03ppm with water changes. On the contrary, water changes are one of the best ways to quickly get tank levels to a more reasonable level. If my PO4 is 2ppm I can drop it to .5 ppm after 2 50% water changes in 2 days and I feel much more comfortable using water changes to get it there than lanthanum or a ton of GFO.

It is also true that water changes are likely the best method of detritus removal. You can run a fine filter or siphon into a filter sock, but when you siphon out detritus it is 100% gone even down to the smallest particles without any special equipment. I wonder how many of our problems with algae, high nutrients, low pH, etc could be solved by just siphoning out detritus.

I firmly believe that keeping detritus out of every area of the tank is one of the most important things to the long-term success of any tank. You can do it without water changes but I think some overlook water changes because of a dogmatic I Don't Do Water Changes position. Targeted cleaning with water changes is not the same as doing a water change periodically because that is what I am supposed to do.

 

[Sral]

I'm absolutely new to the hobby, but from what I understand it depends on the situation.

If the water you put back in is the same as the water you started with, you could see it as a filtration, as any pollutant will be reduced by 1% for every 1% of water replaced. It is however not quite as clear cut, since you might also bring in all kinds of new things, depending on the water you use. I therefore regard them as a quick fix for situations that call for it, like emergencies or when your system is not fully set up yet.

 

[Shooter6]

Yes on small to medium systems or for major issues. Otherwise the effectiveness is questionable.

 

[Ef4life]

Simple answer is yes they are.

but it depends on how big the wc is, frequency, what you do before and during (vacuum sand, suck out algae etc, vs auto water swap), size of the aquarium etc.

some tanks it could be the absolute most effective way of filtration, some it would be horribly inefficient and not work.

 

[Calm Blue Ocean]

Sure, as long as you change an appropriate amount of water. After 2 years my 50-gal tank is finally feeling stable with just 10% per week, and I don't feel like the world will end if I end up missing a week. When I was fighting high nutrients there were some weeks where I did 3 x 30% water changes in a row! I sure hope I'm past that.

My 10-gal tank, with no skimmer or other more advanced filtration, gets as much as 50% each week.

Just like everything you need to read the room and take appropriate action, there isn't a one size fits all with water changes.

 

[glency]

Only if detritus is stirred up or targeted.

 

[Randy Holmes-Farley]

Water changes may be the only way to remove certain organics.

 

[MoshJosh]

I definitely do weekly water changes, and “believe“ in water changes, that said, I voted no. Maybe it’s just semantics, but I don’t see water changes as cleaning the water more so diluting it, and adding elements.

 

[Randy Holmes-Farley]

Math tells us:

1. You can not keep a tank at proper levels long term with water changes where the new water is at sea levels.

2. You can also not remove pollution long term using water changes.

You must have taken different math classes than I did. lol

Math tells me it does reduce pollution long term.


Water Changes in Reef Aquaria by Randy Holmes-Farley - Reefkeeping.com

example:

Figure 3. Nitrate concentration as a function of time when performing water changes of 0% (no changes), 7.5%, 15% and 30% of the total volume each month. In this example, nitrate is present at 100 ppm at the start, and is accumulated at a rate of 0.1 ppm per day when no water is changed.

 

[Hermie]

if you filtered the water before it goes into the tank then of course its a filtration method

 

[Freddy0144]

I look at it like this, with those that dose we are spending money to dose the tank maintain certain levels only to change those levels with water changes,

trace elements can be dosed back to the tank, nitrate and phosphate can be removed other ways.

ultimately, unless there is some type of chemical exposure or some type of emergency I don’t think that doing water changes is the answer.

that being stated I am also running a system that is 200 gallons of water which makes them cost ineffective.

for smaller systems this may be the best way to go.

 

[Bruce Burnett]

I think filter by definition would mean removing something from the water. So by definition. A water change is not filtering anything. It's a replacement.

So a water change or replacement is a known effective way to replenish your aquarium.

True but a 25% water change will reduce nitrates and phosphates about 25%. So as a nutrient reduction method it helps since you are removing from system. Many feel if you have enough methods in use they are not needed.

 

[Dav2996]

Coming from a small tank (20g)I do not even think water changes help but create more issues. You have to test the new water and make sure it matches the tank. Corals do not like change. I doubt everyone is doing 10 tests on their new water to make sure all the parameters match. I 100% support no water changes unless it’s an emergency

 

[Sral]

You must have taken different math classes than I did. lol

Math tells me it does reduce pollution long term.


Water Changes in Reef Aquaria by Randy Holmes-Farley - Reefkeeping.com

example:

Figure 3. Nitrate concentration as a function of time when performing water changes of 0% (no changes), 7.5%, 15% and 30% of the total volume each month. In this example, nitrate is present at 100 ppm at the start, and is accumulated at a rate of 0.1 ppm per day when no water is changed.

You must be awfully sure about yourself, might want to think asking what he meant first ^^
It all depends on what he meant with "proper levels" and "long term pollution".

If "proper levels" mean "ocean levels", where the water has no accumulation due to the vast reservoir and natural filtering cycles, he is actually right. No amount of thinning, maybe short of something like 100% per day with continuous exchange, will bring pollution levels down to baseline.

If "long term pollution" means a constant accumulation of pollutants that the tank can't cycle itself fast enough, like nitrate without enough anaerobic bacteria and/or plants, no water change will get rid of the accumulation itself, it will only fight the symptoms (e.g. buildup).

At least that's as far as I understand ^^