Water Change When and how much Hmm.

[kingclam52]

Hello My friends I`ve been asked how often should you do a water change once a week or once every two weeks or once a month and at what % what is your opinion and what works for you.

 

[currentking]

i do 10% a week. answers will vary!!!

 

[Karen]

I do about 10% each week.

 

[Velodog2]

answers will vary!!!

This.

I do 20% per week.

You are probably looking for some rationale for these answers to base your procedure on. The goals are to a) export nutrients and replenish trace elements and b) promote stability in the tank. From (b) it follows that higher frequency is better with some people even pursuing the nirvana of continuous water changes just because of this. Most people don't exceed one change per week. The first goal (a) determines how much water to change, and that depends on your tank size, bio load, and what other means you have in place for nutrient export. There is no nirvana optimum here as the extreme of a complete water change (assuming sterile artificial salt water is used) is not good either, although if you have access to real seawater that changes things. So you have to find out what works for you.

There are lots of other factors including some barely-hidden goals which might include things like minimizing workload for tank, or trying to prove how good your husbandry practices are by showing that your tank can go for "impressively" long periods between changes (with the presumption that water changes are a simple crutch for people who don't know how to care for their tank - a fallacy in my opinion). But neither of these are in the best interest of the tank.

 

[watdachuck]

I do between 5-10 gallons per week on my 40 Gallon nano reef, sooooooo 12 to 25% weekly.

I would do less with a larger tank, but the nano just doesn't have a great nutrient export system (refugium etc.).

 

[mfinn]

I do 20% every two weeks.

 

[Diamond1]

I do 20% weekly on my 29 it helps me keep my paramaters in check. I may go to bi weekly 20% changes but since the tank is fairly new and lightly stocked I want to see how it reacts to weekly changes.

 

[mikellini]

This.

I do 20% per week.

You are probably looking for some rationale for these answers to base your procedure on. The goals are to a) export nutrients and replenish trace elements and b) promote stability in the tank. From (b) it follows that higher frequency is better with some people even pursuing the nirvana of continuous water changes just because of this. Most people don't exceed one change per week. The first goal (a) determines how much water to change, and that depends on your tank size, bio load, and what other means you have in place for nutrient export. There is no nirvana optimum here as the extreme of a complete water change (assuming sterile artificial salt water is used) is not good either, although if you have access to real seawater that changes things. So you have to find out what works for you.

There are lots of other factors including some barely-hidden goals which might include things like minimizing workload for tank, or trying to prove how good your husbandry practices are by showing that your tank can go for "impressively" long periods between changes (with the presumption that water changes are a simple crutch for people who don't know how to care for their tank - a fallacy in my opinion). But neither of these are in the best interest of the tank.

Water changes of less than about 50% are a poor way to either reduce or increase anything (nutrient removal or trace element replacement). And since most people (nano reefs aside) find this difficult, it's far easier to find another method of nutrient removal and/or trace element replenishment. So there's A.

As for B, if one wanted to promote stability, why would one consistently introduce change into the system? I suppose a 10% water change doesn't have a huge effect on water chemistry just by virtue of its size, but it is certainly enough to mess with my skimmer and often my corals close up for a while shortly after. So if I wanted complete stability, I would do it a different way...

The exception to this is a continuous water change system. Changing out 1-2% per day by way of an automated pump system definitely promotes stability because the amounts are so tiny. As well, you could end up changing between 40-80% or so of your total water volume every month (once you consider that you're also removing a little of the new water you just changed, so you lose a bit of efficiency this way). However, this can be cost prohibitive for large tanks, depending on the cost of salt. Still, I might go this way one day.

I think the true reason to do standard water changes is mostly to prevent the buildup of things we can't test for or otherwise remove, such as heavy metals, toxins, etc. However, again, without large volumes, the effectiveness is limited. Running carbon or other chemical adsorbants can help to remove some of these, but not all, so certainly changing some water is better than none. But to promote stability in my aquarium, I change only 5% every two weeks. I could probably do 5% per week but I'm trying to minimize maintenance and spend more time with family.

So, short answer: on a medium-large size tank, 5% every two weeks is probably the minimum you want to shoot for. You should probably also run carbon, and have figured out some other method of nutrient removal (I use a strong skimmer and dose vinegar). Dosing trace elements is definitely optional. On a smaller tank, if you can, try for 50% every two weeks. This might be enough to remove and replenish everything, depending on bioload.

 

[kingclam52]

I want to thank you all for your feedback have a great day and happy reefing.

 

[Randy Holmes-Farley Verified Community Expert]

IMO, changing smaller amount more frequently has a lot going for it. I change the equivalent of 1% daily, in about 10 x 15 minute periods each 254 hour period.

This article has more:

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

from it, why I do water changes:

Conclusion
Water changes are a good way to help control certain processes that serve to drive reef aquarium water away from its starting purity. Some things build up in certain situations (organics, certain metals, sodium, chloride, nitrate, phosphate, sulfate, etc.), and some things become depleted (calcium, magnesium, alkalinity, strontium, silica, etc.). Water changes can serve to help correct these imbalances, and in some cases may be the best way to deal with them. Water changes of 15-30% per month (whether carried out once a month, daily or continuously) have been shown in the graphs above to be useful in moderating the drift of these different seawater components from starting levels. For most reef aquaria, I recommend such changes as good aquarium husbandry. In general, the more the better, if carried out appropriately, and if the new salt water is of appropriate quality.


Calcium and alkalinity, being rapidly depleted in most reef aquaria, are not well controlled, or even significantly impacted by such small water changes. In order to maintain them with no other supplements, changes on the order of 30-50% PER DAY would be required. Nevertheless, that option may still be a good choice for very small aquaria, especially if the changes are slow and automatic.

 

[cosac285]

Water change is much expensive, for me, water change is not a problem because I'm using a natural way which is cycle,and decoloration of the water as well. with the help of those plants, Chaeto, mangrove and seaweeds we called it lato in tagalog all together in my 30gals. refugium ditritus drifting down directly into my refugium no need a skimmer or what so ever devices just a florecent or led lights for my refugium. I recomend not to use mixed chemical for your coral recedue will remain in your tank that can affect some of your bioloads. Use a calcium reactor instead. My water now is already more than a year with out water change.I decided to check my water status still going right all my bioloads are remain healthy.and I decided to put additional palumpong tree leave in the most costal in the philippines best for filtration that a mangrove can do fully tested and undergone for a study.

 

[tyler1503]

I used to do 1-2% every day. I then stopped doing water changes completely as life got in the way and now I do about 10% a week.
My colour was noticeably nicer with the small daily changes and I got more growth with no water changes. I won't comment on the weekly 10% until live been doing for longer than just a few months I'm hoping it will be a nice balance between the other two.

 

[mrcoffee2]

I don't do WC... I dose trace elements - thats it.

If I ever do replace water it is because I had to suck out the detrius that collects on the bottom of the tank once every 3 or so months.

To the OP everyone is different, have to find what works for you. I'd say the average around here is 10-20% weekly / biweekly.