Water Changes or AWCs... is one better than the other?

What do you think of auto water changes?

  • Best thing ever!

    Votes: 47 43.1%
  • It's good, but doesn't seem as effective as weekly/bi-weekly

    Votes: 9 8.3%
  • I'd like to do it, but haven't

    Votes: 40 36.7%
  • I prefer the old fashioned way

    Votes: 13 11.9%

  • Total voters
    109
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Randy Holmes-Farley

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I'm probably the wrong person to ask since I only do water change twice a year (mainly just to clean the sand bed). AWC seems pretty wasteful in that a portion of the water you are taking out today was just put in yesterday.
That's not a useful way to think of it.

A better way is to just compare how changing 30% once a month compares to changing 1% a day (or even continuously) on a parameter of some sort.

The difference is small for this size of change:

Water Changes in Reef Aquaria

from it:

Figure 13. An overlay of Figures 3 and 12 to allow comparison of the differences between nitrate depletion using daily and monthly water changes of the same amount changed.

1590443297012.png
 

Randy Holmes-Farley

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I've had an AWC running for about 6 months. I'm not a big fan because I have a 260g system and can only change out about 1-2g at a time from my sump before my return pump starts sucking air. I do like the ATO part, but I've found that if you're running a DC pump and vary the speed over the course of the day you run the risk of topping off during high flow periods and chaning out 5g of water with 2g. Things can get out of whack quickly. I've had a couple times when my sump was within 2 inches of overflowing so no more auto changes for me, I do it manually through the AWC but still takes too long since my water is gravity fed from garage (saltwater flows much slower than RODI).
My system was substantially bigger, and it works fine to run the in and out at the same time (I used a single pump with two pump heads). Just take the the water out from a sump slightly upstream of where it goes in and there is no waste.
 

Randy Holmes-Farley

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This is def true, and part of the reason why 2% changed daily doesn’t actually equal 14% weekly, for example (Prob more like 10% net). It does add stability overall though.
2% daily equals exactly 13.2% changed once a week. It's a VERY small difference.
 

Randy Holmes-Farley

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Yup I second that. ATW is great for the water change itself, but I still have to suck out the detritus from sump
Manually , and from the tank if you are going bare bottom.
I never removed detritus. :)
 
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bam123

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Love doing continuous AWC. Makes dosing of additives like 2 part easy. Best results of any aquarium I have had over 20 years yet. Make my water once a week (10 minutes), turn it back on and done.
 

weamdog

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My system was substantially bigger, and it works fine to run the in and out at the same time (I used a single pump with two pump heads). Just take the the water out from a sump slightly upstream of where it goes in and there is no waste.
Didn't realize simultaneous was even possible with the AWC (Smart). When i do manual, it does sequential. I think even that would be an issue since the output line is larger and pumped and the input is gravity fed rodi line. One of these days I'm going to increase the size of the saltwater line so that it can be used for large changes instead of me running tubing throughout the hose.
 

Laith

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I've been thinking about setting up AWC on my system. I typically change ~100g every 2 weeks on my 600g system. What equipment and schedule do you use?
I use the Spectrapure Litermeter III and change 1% a day on a 1900l (500g) system.

I was initially going to use the GHL Maxi Doser but the thing sounds like a vacuum cleaner :rolleyes:.
 
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Waters

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I use AWC to change roughly 13 gallons a week on a 130 gallon system. As far as removing detritus from the sandbed, I use a Fluval vacuum which doesn't remove water when cleaning the sand bed. I do that monthly.
 
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Angelwolf21203

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I use AWC to change roughly 13 gallons a day on a 130 gallon system. As far as removing detritus from the sandbed, I use a Fluval vacuum which doesn't remove water when cleaning the sand bed. I do that monthly.
Do you like that vacuum? I've pondered it many times, but wondered if it was worth it.
 

Waters

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Do you like that vacuum? I've pondered it many times, but wondered if it was worth it.
So far I like it but have only used it a couple of times. It got a lot of bad reviews due to poor suction but I haven't had any issues at all so far. I like being able to clean without removing a bunch of water.....especially since I switched to AWCs.
 

Randy Holmes-Farley

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Didn't realize simultaneous was even possible with the AWC (Smart). When i do manual, it does sequential. I think even that would be an issue since the output line is larger and pumped and the input is gravity fed rodi line. One of these days I'm going to increase the size of the saltwater line so that it can be used for large changes instead of me running tubing throughout the hose.
I do not know that it is with any particular system. i just used home depot timer and a dual head pump. I don't think anything fancy is required for AWC.
 

Amado

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In my opinion awc are great for small tanks.
Once you get to 100 gallons or more it make less sense. I had a 125 gallon tank and I was doing 2 gallons a day AWC on a dose that was ok. The dos ran almost all day to be able to make that change and it’s loud. You will also need to replace the heads on the dos sooner.

My setup now is 210 gallons with two 50gallon frag tanks in the same system.
AWC just don’t make sense since I can change 50 gallons of water by turning two valves.
 

Waters

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In my opinion awc are great for small tanks.
Once you get to 100 gallons or more it make less sense. I had a 125 gallon tank and I was doing 2 gallons a day AWC on a dose that was ok. The dos ran almost all day to be able to make that change and it’s loud. You will also need to replace the heads on the dos sooner.

My setup now is 210 gallons with two 50gallon frag tanks in the same system.
AWC just don’t make sense since I can change 50 gallons of water by turning two valves.
I am confused as to why your DOS ran all day? You set the time frame you want the water to swap out. I change 2-3 gallons a day, every day between 4-6 in the afternoon. You are correct though, the heads will have to be changed at some point....fortunately they are easy to swap out and are relatively inexpensive. I do them approximately once a year.
 

Amado

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I am confused as to why your DOS ran all day? You set the time frame you want the water to swap out. I change 2-3 gallons a day, every day between 4-6 in the afternoon. You are correct though, the heads will have to be changed at some point....fortunately they are easy to swap out and are relatively inexpensive. I do them approximately once a year.
For me and my setup it’s just not worth it.
It’s so easy for me to make water changes that it doesn’t make sense to use up a dos for that. I open and close two valves. No buckets. So I my case it doesn’t make sense.
I also had to turn off the skimmer and /ato while the wtc was going on. I work from home so I can’t run it during the day and at night the sound of the dos is to loud.
 

Waters

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For me and my setup it’s just not worth it.
It’s so easy for me to make water changes that it doesn’t make sense to use up a dos for that. I open and close two valves. No buckets. So I my case it doesn’t make sense.
I also had to turn off the skimmer and /ato while the wtc was going on. I work from home so I can’t run it during the day and at night the sound of the dos is to loud.
Makes sense. I don't have to turn off the skimmer or ATO...it adds water back in as it is taking it out so the levels never change. Fortunately my DOS an sump are in the basement so I don't have to listen to it.....I agree, it is loud.
 
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