What's more effective. Frequent smaller water changes or single huge ones?

FINWIN

Dovii
Original poster
MFK Member
Dec 21, 2018
956
883
100
Washington DC
I've been thinking about the effectiveness of water change size vs frequency. My understanding is that generally less then 20% per change is a waste of time.

Does tank size play a factor in this? 20 percent of 300 gal is far different than 20 percent of a 55. My largest tank isn't a concern but I am still experimenting with my 38 gallon tanks. Each tank has a single large bp...they muck up the filter pads every 2 days. And I'm talking mud like. All the bio sponges I leave be, and the pothos helps. Ideally if I had space I'd put them each in a 55 but the fish room is a weird, wedge shaped space with only one long wall (the 225 is on that side).

Unless there's an obvious problem I rarely test with API kit. Mostly I do the eye test and monitor. The parrots immediately color up intensely and 'perk up' with fresh water, so I look for these signs. Increased activity (zipping around, fins out and up) are my indicators. So right now I'm comparing back to back smaller w/c (20%) versus one small (15-20%) and one large (50%) per week.

W/C schedule for the 225 remains the same, twice a week at 50-65% percent. No issues and lightly stocked (11" Oscar, 6+" BP, 6+" Severum, 2 syno catfish (5" and 7" inches). Because most if not all of these fish are still growing I maintain the same regimen. I believe the Oscar's ultimate size may determine if more w/c is needed. Since he's only around a year old I expect him to make even more waste down the road. If the BP gets to 8+ inches the game definitely changes.
 

Dloks

Probation Member
Probation Member
Feb 5, 2011
1,877
2,762
164
in a car
I've been thinking about the effectiveness of water change size vs frequency. My understanding is that generally less then 20% per change is a waste of time.

Does tank size play a factor in this? 20 percent of 300 gal is far different than 20 percent of a 55. My largest tank isn't a concern but I am still experimenting with my 38 gallon tanks. Each tank has a single large bp...they muck up the filter pads every 2 days. And I'm talking mud like. All the bio sponges I leave be, and the pothos helps. Ideally if I had space I'd put them each in a 55 but the fish room is a weird, wedge shaped space with only one long wall (the 225 is on that side).

Unless there's an obvious problem I rarely test with API kit. Mostly I do the eye test and monitor. The parrots immediately color up intensely and 'perk up' with fresh water, so I look for these signs. Increased activity (zipping around, fins out and up) are my indicators. So right now I'm comparing back to back smaller w/c (20%) versus one small (15-20%) and one large (50%) per week.

W/C schedule for the 225 remains the same, twice a week at 50-65% percent. No issues and lightly stocked (11" Oscar, 6+" BP, 6+" Severum, 2 syno catfish (5" and 7" inches). Because most if not all of these fish are still growing I maintain the same regimen. I believe the Oscar's ultimate size may determine if more w/c is needed. Since he's only around a year old I expect him to make even more waste down the road. If the BP gets to 8+ inches the game definitely changes.
I change 75% religiously 2x a week on all my tanks, if I’m out or on vacation, someone will do a w/c for sure. Whether you have crappy filtration or the best it’s always recommended to change your water 2x a week if not more. I would change my planted tank more but apparently it’s not recommended to change it out more than once a week.
 

FINWIN

Dovii
Original poster
MFK Member
Dec 21, 2018
956
883
100
Washington DC
What size are your tanks?

All my tanks are twice a week as well but the only difference is I'm experimenting various amounts on the smaller tanks since they foul faster.
 

RD.

Crazy Canuck
MFK Member
May 9, 2007
10,815
6,642
2,780
60
MFK
10%, 25%, 50%, 90%, once a month, once every 2 weeks, once a week, or 4 times a week - is all dependent on ones bio load, and what is required from the hobbyist to keep pollutants at a near zero value. The only thing that should be set in stone, is the latter portion (pollutants at near 0 value), and what that will require in terms of water changes will vary from tank to tank, based on the stock in that tank, and the overall volume of water. A 100 gallon tank with 25 guppies obviously would require less water volume changed out each week, vs a 100 gallon with six large Oscars.

FINWIN FINWIN if as you say
Each tank has a single large bp...they muck up the filter pads every 2 days. And I'm talking mud like.
Then it sounds to me like you need to do some tweaking, via increased water changes & filter cleaning, and/or upgrade to a much larger volume of water, and possibly additional filtration.
 

FINWIN

Dovii
Original poster
MFK Member
Dec 21, 2018
956
883
100
Washington DC
Filtration on each is powkoo sponge rated for 40, and a hob aqueon rated for 30-50 and airstone...thought it would be enough but surprise on me!

Yeah, I think now my big bp's are maxing out the 38's...will keep tweaking with more w/c. Hopefully can figure out space down the road for 55's, that would be ideal. The parrots have grown a bit since I got them and it may be at the 'tipping point' with my current w/c schedule.
 
  • Like
Reactions: islandguy11

kno4te

MFK Moderators
Staff member
Moderator
MFK Member
Dec 24, 2005
12,625
11,359
480
USA
Think both are effective. Depends on bioload. Think the small and frequent water changes keep some stability with the water. Not much swings with ph and Gh.
 

esoxlucius

Redtail Catfish
MFK Member
Dec 30, 2015
1,182
1,760
154
51
RD is spot on. It all depends on bio load. Even the 20% water change you mentioned as being a "waste of time", and most would agree, could in fact be a good amount to change out, if you had a couple of guppies in a 100g!

Each hobbyists system is different, whether it's tank size/overall water volume or stocking or feeding regime or maintainance schedule. They are all important factors in determining what your bio load is.

I had two 180's and to keep nitrate levels in the orange on the API chart, one was fin level every 4 days, the other was fin level every 8 days. I got rid of of one of them and replaced it with a 360. At the moment, through testing my water regularly, i'm gradually getting to grips with my new water change schedule on both tanks because one of them's new and an unknown quantity and the other has had a stock change.

In short, your water changes, how often and how much, should be a reflection of what's going on in the forever changing environment of your tank.
 

FINWIN

Dovii
Original poster
MFK Member
Dec 21, 2018
956
883
100
Washington DC
RD is spot on. It all depends on bio load. Even the 20% water change you mentioned as being a "waste of time", and most would agree, could in fact be a good amount to change out, if you had a couple of guppies in a 100g!

Each hobbyists system is different, whether it's tank size/overall water volume or stocking or feeding regime or maintainance schedule. They are all important factors in determining what your bio load is.

I had two 180's and to keep nitrate levels in the orange on the API chart, one was fin level every 4 days, the other was fin level every 8 days. I got rid of of one of them and replaced it with a 360. At the moment, through testing my water regularly, i'm gradually getting to grips with my new water change schedule on both tanks because one of them's new and an unknown quantity and the other has had a stock change.

In short, your water changes, how often and how much, should be a reflection of what's going on in the forever changing environment of your tank.
I'll probably be looking at bumping up the hob aqueons to aquaclear 75s. Normally I'd call overkill but these thick cichlids have a real capacity for waste. The parrots are chunky softballs and like water movement so I don't think the extra power will bother them.

I can take the ceramic ring pouches and move them over to the larger filters. The sponges I don't touch unless they gunk up...the only gunk buildup is pretty much confined to the filter pads. The prefilters and filters thankfully stay clear.

The 225 is part hob and part custom filters. 3 aquaclear 110s, two 4" airstone disks and two custom corner filters with 1 gal bio bale each run by powerheads. Pothos also keeps nitrates in check. The aqua clears contain 1 fiter pad, 4 bags ceramic media and 1 bag phosguard each. Sponge prefilters are on the stems. With the water movement I almost never see turds...they get swept up and collected into the filter pads. Nitrates are negligable, maybe ~5 -10 on average.

BUT all that being said, and even with light stocking and huge water changes the filters pads definitely show the heavy load an oscar, parrot, and severum can put out. The severum is the biggest surprise, Chip has literally laid carpets of waste in the past. I don't consider the synos major wasters (correct me if I'm wrong). The pads usually are dirty, cleaned twice a week with each w/c. Sponges and prefilters stay clear.

So it's clear that even in the 225 larger w/c will still be needed down the road. All of the fish are still growing, some faster than others.
 
  • Like
Reactions: Fishflyer

duanes

MFK Moderators
Staff member
Moderator
MFK Member
Jun 7, 2007
13,828
9,906
2,880
Isla Taboga Panama via Milwaukee
Most commercial filter ratings are based on average community tanks with a few small species, like small gourmamis, an angel and some tetras, or a similar minor bio- load.
If you have large fish like oscars and other cichlids, or other monster fish, those ratings are not at all relevant, in fact they are basically ridiculous. One large cichlid in too small a tank, is the equivalent of a small community tank of 1,000 tetras, or 2000 guppies.
Everyone must decide what a realistic goal is for themselves, and the fish they intend to provide adequate care for.
I have always set a nitrate load of 5ppm for my tanks. This meant when I was in the states, a 30%-40% water change every other day was needed to maintain that goal, meaning over 100% per week. Because I specialized in spawning cichlids though, this IMO was needed.
Filtration is to me, not relevant as far as nitrates go, because most normal filtration methods don't contribute at all toward nitrate reduction, its really only about water changes.
I also monitor pH and alkalinity, if either drop significantly, its time for a water change.
This also depends upon the species kept.
For riverine species a moderate drop in pH may be no problem, but for other more specialized fish constant small bumps in pH in either direction may be significant to their long term health, so more small water changes may be desired, as opposed to one large one which allows water parameters to swing wildly, most cichlids are on the tolerant side, but a few aren't, and in many cases diseases like hole in the head, or bloat are the result.
 

Fishflyer

Candiru
MFK Member
Nov 23, 2018
582
221
46
Water changes, large or small--bring on the rain, the fresh waterfall or fresh undercurrent !!

You are the water god.

Whether your fish revel in the fresh water or not, if you are tuned into your fish, you will note in many cases a marked difference in your fish's behavior, varying dependant on the species when you do a water change. I enjoy that they enjoy it.

I have a few aquariums and alternate small and large water changes as a routine, including my Bettas, and my Bettas like the fresh water. None of my fish are heavy polluters, my tanks are heavily planted so once a week suffices.

Alternating 20% and 50% water changes. I don't know if it necessary, but with larger water changes I add Stress Zyme to encourage the beneficial bacteria culture.

Whatever works for you and your aqua denizens.

Nice going Lady Finwin, another interesting relevant topic and inclusive seminar.
 
zoomed.com
hikariusa.com
aqaimports.com
Store