Water changes-daily vs weekly?

Faulkner’s maze

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Hi Randy
Something I was thinking about-
I have 95 gallons by volume.
I am doing 30 gal a month-one gal a day
Would it be more effective to do weekly by 7.5 gallons one day a week instead?

Is incremental better than weekly in this case or it doesn’t matter?
Thanks

LB
 

Dr. Reef

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better to do more smaller water changes vs large few changes,
 

André Brasil

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If I remember correctly, from an in depth, specialized article on this, doing a 30% water change monthly is only slightly more impactful than a dayly 1% water change done over a month.
 

beaslbob

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with a 1 gallon per day vrs a 7 gal per week, the levels just before water changes would be the same assuming the tank has reached the end point. What would change is the levels after the water change.

assuming 1ppm increase per day, and a 100 gallon tank (just to make number easy) the water changes are 1/100 per day on the daily schedule and 7/100 weekly. The daily build up is 1ppm and weekly is 7ppm.

They will build up to where the increase is removed by the water changes. Daily it's 100ppm down to 99ppm then back up to 100ppm. Weekly it builds up to 100ppm down to 93ppm then back up to 100ppm.

Note a similar thing happens with decreases in say calcium. assuming 400ppm replacement water the daily results in 300ppm before water changes up to 301 then down to 300 again. weekly 300ppm up to 307 then down to 300 again.

To me and FWIW the important things is to balance out the system so that the 1ppm/day is as close to 0 as possible. ammonia, nitrates, phosphate through algaes for instance. calcium alk mag through some kind of dosing. Under those conditions the tank just stays at acceptable levels regardless of water changes.

my .02
 
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Dr. Reef

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smaller daily changes, impact on elements in saltwater will be less and gradual change while if saltmix numbers are different than tank a large water change can bring certain elements up or down too quickly which can shock the tank.
 

Ghost463

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In my experiences drip and overflow systems are the best. This slowly fills the tank during the whole day right?!.
Not to say a once a week is a bad thing either. Better then most i would think.
 

Shaun Sweeney

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But ... what if you are using ocean water? A biologist at our local Fed Fisheries has looked at our ocean water and points out that during the first few days, there are way more beneficial organisms present than if the water is left to sit. That is the main reason I have stuck to weekly water changes. It's not practical for me to haul new water daily. Comments?
 

vetteguy53081

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Weekly should be sufficient, Bi-weekly once well established and daily only if a water quality problem exists.
 
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Faulkner’s maze

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If I remember correctly, from an in depth, specialized article on this, doing a 30% water change monthly is only slightly more impactful than a dayly 1% water change done over a month.
Do you remember where you read the analysis?
 
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Faulkner’s maze

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Weekly should be sufficient, Bi-weekly once well established and daily only if a water quality problem exists.
Except for an ongoing phosphate issue (gfo and chaeto) and I dose alk/ca just looking for the optimal rate.
 

André Brasil

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Do you remember where you read the analysis?
I do now!

"While lots of smaller changes (say, 30 changes of 1% each) are slightly less efficient than one larger one (30% in a single batch), the difference is small (30 changes of 1% each exactly matches one 26% batch water change), and consequently other factors of convenience or stress on organisms."

Was from Randy's article, posted above.
 

BradB

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A 45.6% water change every other month changes almost exactly the same amount of water as a 1% water change every single day, and uses almost exactly 75% of the salt. To me, saving 25% of my salt budget and doing less manual work is worth it. But I can certainly see people feeling the trade off is better the other way - especially if they have $1000 pencil eraser sized frags instead of huge colonies of cheap coral being eaten almost as fast as they grow by really cool non-reef-safe fish.
 

Land Shark

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Randy Holmes Farley has a new gig and said he would be offline more often for a bit so I will share something on this that I recall him discussing on another thread. He compared the daily automated water change method to larger weekly changes and said the improved efficiency of a weekly water change is minor. Something along the lines of about a 2% difference if memory serves correctly. He even had a formula comparing the two. He also said he prefers automated daily water changes for the stability (fewer alk swings, easier) benefits and that is what he ran himself in his own tank.
 
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Faulkner’s maze

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Randy Holmes Farley has a new gig and said he would be offline more often for a bit so I will share something on this that I recall him discussing on another thread. He compared the daily automated water change method to larger weekly changes and said the improved efficiency of a weekly water change is minor. Something along the lines of about a 2% difference if memory serves correctly. He even had a formula comparing the two. He also said he prefers automated daily water changes for the stability (fewer alk swings, easier) benefits and that is what he ran himself in his own tank.
Thanks! I was think biweekly but may just stay with daily. It really doesn’t matter as to frequency so much as I don’t have to deal with the manual labor so it really is about the...most “ideal” method if you could call it that. I was just getting into the article posted above.
 

Randy Holmes-Farley

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But ... what if you are using ocean water? A biologist at our local Fed Fisheries has looked at our ocean water and points out that during the first few days, there are way more beneficial organisms present than if the water is left to sit. That is the main reason I have stuck to weekly water changes. It's not practical for me to haul new water daily. Comments?
That's a fine reason to use larger and less frequent changes.

Otherwise, I typically prefer and did smaller ones (actually, nearly continuous in my system, with 20 15 minute periods of slow water change each day).

As to the actual effect on the efficiency of the change, I discuss that and show graphs and such in the article linked above. :)
 

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