What's the "magic" of 10% weekly water changes?

[dopey]

I think it instills a discipline needed for this hobby as well. A big part of success(I think) is folks that are able to have a consistent routine, either manual or automated, and sustain that over a long period of time. Instilling a healthy water change habbit(and maintaining it) is a good way to enforce discipline to a new reefer.

Discipline and Patience are key to success in this hobby.

 

[S2G]

It's just a general rule & a number to shoot for. Easier on the pocket for water changes before there were nano tanks as well I think.

 

[palmer]

I do 20% per month- no issues

 

[chipmunkofdoom2]

There's nothing magical about changing 10% of your tank's water per week. I think the hobby has settled on 10% weekly because it represents a "sweet spot" in a lot of regards.

First, it's a small amount, so it's easy to mix and change. Most tanks just need 5 - 10 gallons. That's a hardware store bucket or a small 10g Brute trash can. If maintenance is easy, there's a better chance that you'll do it regularly. If you ask experienced reefers, many will say that regular maintenance and the stability that comes with it are the most important factors for long term success.

Second, the small and easy 10% weekly change adds up to about 36% changed per month. That's a healthy amount, in line with the historical "25% per month" typically recommended in the hobby.

Sort of on the same topic as the last point, a 10% weekly water change is likely an optimal amount for most tanks. Could you get away with more or less than 10% per week? Probably. I just don't think that level of experimentation is worth the effort to most reefers. Most would just prefer to do a simple and fast 10% weekly change, knowing that many hobbyists out there have success doing exactly the same thing.

 

[Kellie in CA]

10% works for me. I have a Nano, so it's really easy to change out 2 gallons per week. Do dosing, no skimmer. Easy Peasy!

 

[John Hathaway]

I've never had any livestock go into shock because of too big of water change, and I've done 70%+ many times.
Sometimes, bucket size dictates how big of a change I do. I have a twenty (probably fifteen gallon volume) that I usually do five gallon water changes on because I can vacuum the sandbed for longer.
There's no definite rule, but nutrient levels should serve as your bare minimum water change capacity, and let cost serve as your ceiling. Don't overthink it.

If you use an RODI line you can clean the sandbed and don't have to take out as much water....

 

[beaslbob]

Thanks for your thoughts and I appreciate the impact of water changes. That said, are you saying that you can get a tank to where water changes aren't needed?

yes

I suppose it's possible to come close to equilibrium, but haven't thought about it this way.

I've heard about people using the Triton method (which I can't do based on the underlying requirements) which seems a lot like you're describing. But if you don't do water changes, then wouldn't you also need to have all sorts of other supplements that the "fresh" saltwater would provide?

To me, what you need to do is basically start the system as a balanced eco system right from the start. Using plant life like macro algaes to consume ammonia then nitrates plus phosphates and co2 while returning oxygen, fish food and carbonates. Plus use the improved diy two part, balling marine, or tritent methods to keep calcium, carbonate, magnesium, and trace elements up.

Using such a system means the tank is much less dependent on to independent of the water being used, salt mix used, presence or absence of live rock, live sand, skimmers, and so on. Sure you still need to add food and provide lighting but other than that the tank basically just takes care if itself.

And with such a system all a water change can do allow you the opportunity to make mistakes and screw up the system.

Still that's just my .02

 

[Webslinger]

Interesting. So are you doing this? Would love to hear more details about how you've accomplished it

10% weekly water changes, Kalk in the ATO, Skimmer, Bio-Pellet reactor (10 fish and 2 eels and ton's of corals/anemones in a 60g) Chaeto in sump, Occasional carbon. That's it KISS

I began thinning the tank. Giving away frogspawn and BTA's in top left corner.

 

[Treefer32]

So, I have a 340 gallon display, and 75 gallon sump. (The sump is half full of water to allow for water in plumbing, skimmer, etc to drain into the sump). So, 40 gallons (roughly) in sump, display probably has around 280-300 galloons of actual liquid volume. so, round out to 320 gallons of volume. I change 35 gallons every other week about 11%. I dose two part, have an algae scrubber, skimmer, 25 watt UV (doesn't do much, but, had it on hand and plumbed it in) and a Nu-Clear 25 micron canister filter. No filter socks. 15 fish, lots of LPS, SPS, and softies frags. Not much grown out yet (still stocking over the last 18 months).

Nitrates just tested at 12-16. Which is what there were 3 months ago with 6 x 11% water changes in between. So, I feel like with the 11% I"m doing every other week, I'm maintaining equilibrium. I still have some algae growing and dieing in the display. I would like to get that under more control, but, not sure that I can control that with water changes, I think that's more of a flow and circulation issue.

What's interesting about this -It just hit me...The left side of my tank is nearly algae free. The right side continues to grow algae no matter how many times I clean the rocks.. The left side has two powerheads. One facing back to front and one facing left to right. The right side only has one powerhead and the rocks continuously have fresh hair algae...

So, I just proved - water changes are just 1 part of the nutrient control equation.

The variables:
Inputs (number of fish, feeding)
Nutrient exports: Number of powerheads, corals, cuc, refugium or ATS, skimmer, water changes.

I don't know the relationship of water change volume vs. power head circulation... E.g. can you get by with less flow if water changes are increased by x amount or y frequency?

 

[Lizdoesreef]

Weekly water changes is probably the most important thing you can do to keep a successful reef. It helps export waste, along with your skimmer. It helps replenish your nutrients. 10-20% is a good range to stick by but what percentage u do weekly is dependent on many other factors such as how good your skimmer is skinning, how much fish are in the system, how heavy you feed, and how much corals are in the system which will require more nutrients. To be on the safe side, a heavier percent of 20% would be best. I run a dominant sps tank and thus I do 10% weekly because I don't want too much of an alk spike on the day I do the change. I also dose regularly and have plenty if live Rock and great skimmate.

 

[Potatohead]

A few months ago switched from 12% (what my mixing barrel holds) every week, to every two weeks. Other than nitrate being 8-10 instead of 5-8, I really don't notice much difference in the tank at all.

 

[Webslinger]

When I do 10% weekly my tank is pristine, when I slack it looks like crap!

 

[ReefGrammie]

I change 5% on my 90 weekly mainly for two reasons: 1) My mixing bucket is 5 gallons and 2) I can still carry a 5-gallon jug of water. No magic there! ;Joyful

 

[brandon429]

there's magic in a 100% water change + sandbed full rinse to clarity + live rock clean out/no more packed in detritus. all else is standard water change, the summation is more helpful than the increments but a big rip clean has demonstrable benefits and age-extending characters given to the display running a deep clean.

 

[Salemsoul]

Hello! As I continue to learn about ways to keep my tank healthy, water changes are certainly an interesting topic.

Trying to keep some focus on this, but I know a lot of folks suggest 10% weekly water changes. My question is why 10%?

Why wouldn't you do a 15% or 20% weekly water change?

Is this more about making sure the changes aren't too drastic?

Truly a newbie question, but really trying to understand. Thanks in advance!

Totally valid question! Honestly 10% I see on company instructions a lot.. I don't know of any aquacultured or biology studies that provide data showing a 10% weekly water change is the key to success in an aquarium. From personal & professional experience: your tank volume, nutrient export & bio load should dictate percent% & how often you are doing a water change. It is removing impurities from the water & most salts replace trace elements.

Water changes shouldn't be based on anecdotal evidence but tailored to your actual tank. Is 10% weekly keeping your nitrates consistent? Do you have a low bio load & a large skimmer, so maybe 20% monthly helps maintain your nutrient levels. These are questions I would suggest reefers address when ironing out a maintenance schedule and sticking to that because consistency is key in this hobby.

 

[Randy Holmes-Farley]

Water changes shouldn't be based on anecdotal evidence but tailored to your actual tank. Is 10% weekly keeping your nitrates consistent? Do you have a low bio load & a large skimmer, so maybe 20% monthly helps maintain your nutrient levels. These are questions I would suggest reefers address when ironing out a maintenance schedule and sticking to that because consistency is key in this hobby.

Personally, I don't think nitrate and phosphate are the most important drivers of the need for water changes in most reef tanks. Unfortunately, the things I most want it to do are not readily measured. Some (like certain trace elements that may be declining or rising) can be measured by ICP, others (like accumulating organic toxins and trace elements below ICP quantitation limits) cannot be readily measured at all.

 

[Joedubyk]

Personally, I don't think nitrate and phosphate are the most important drivers of the need for water changes in most reef tanks. Unfortunately, the things I most want it to do are not readily measured. Some (like certain trace elements that may be declining or rising) can be measured by ICP, others (like accumulating organic toxins and trace elements below ICP quantitation limits) cannot be readily measured at all.

This x 100.. It's not about nutrients

I don't think we know WHY WC works so well. I can say this. My corals look SO happy and healthy when I do 20% weekly (or there abouts) with weekly WC and I have an SPS dom tank.

i want to make a caveat: I make sure I change my sediements and carbon blocks often and chaning RO membrance (even if you're getting 0 tds) more often seems to help a lot.

 

[Salemsoul]

Personally, I don't think nitrate and phosphate are the most important drivers of the need for water changes in most reef tanks. Unfortunately, the things I most want it to do are not readily measured. Some (like certain trace elements that may be declining or rising) can be measured by ICP, others (like accumulating organic toxins and trace elements below ICP quantitation limits) cannot be readily measured at all.

I agree with you , My attempt to over simplify what is so often taught to monitor when jumping into the hobby wasn't meant to reduce the more important need to monitor minor & major elements. WC's are used for the replacement or removal of trace elements which we know is important for coloration, symbionts & their efficiency. The thing that is being told over & over in regards to wc's as a fix is "your phosphates are this # & nitrates are this # ... therefore you need to do 10% weekly water changes." Consumption & Management of minor and major elements, managing organics & waste is a tall order for new reefers. Thank you for identifying the need to correct my last statement.

 

[Webslinger]

I haven't tested my water except for temp and salinity in over 2 years.

 

[Joedubyk]

I haven't tested my water except for temp and salinity in over 2 years.

What kind of tank do you have? Softy? Lps? Mixed?