Constant automatic water changes

Dr.DiSilicate

Great White Shark
M.A.S.C Club Member
ex-officio
#1
Who is doing this, what have you found? Has it been worth the investment? Would you do it again? In theory what are the positives and drawbacks?


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TheRealChrisBrown

Reef Shark
M.A.S.C Club Member
ex-officio
#2
I tried it for 2 months, not sure I gave it enough time to make a difference. I will say auto water changes seem to be a lightning rod issue....people either love it or hate it. Curious to see what others think.
 

Andrew_bram

Tiger Shark
M.A.S.C Club Member
#3
Interested in this as well. I have a dose laying around but have not been sold on the idea yet. Hope some folks chime in.

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flagg37

Anthias
M.A.S.C Club Member
#4
I ran one with my DOS off of one head. I drew out like 2 gallons every night and then ran the same head in the reverse direction to draw in 2 gallons of the fresh salt water. I had a T fitting with a check valve to accomplish this.

I ran it for a couple months at the beginning of the tank life. I felt like I was just wasting water though so I turned it off. I think after the tank was more established it would have been more of a benefit.

I chose to go a different direction though and stopped all water changes. Instead my nutrient export was handled by my chaeto and I dosed trace elements (and the major ones but that’s kind of a given).

I think of it as just another tool in your arsenal that you can use when it fits the bill for what’s needed.
 

halmus

Registered Users
M.A.S.C Club Member
ex-officio
#5
I don't use constant water changes personally. However when I do conduct water changes, I add the new water to the display and open a valve on my sump which is located just above the normal water line. The new water obviously adds to the total system volume displacing water out of the sump and down the drain. I've grown to like this approach because I don't have to remove "X" gallons of water and replace with "X" gallons of new. It's a lazy approach but assuming the new water is well mixed in before reaching the sump, I have a very stable, low impact, but effective water change.

Back when I was at the University of Washington as an undergrad, I wrote a short paper comparing the two methods. I assumed that removing say, 20 gallons and then adding back in 20 gallons was the most effective way of exporting nutrients. I couldn't imagine that simply adding in new to the existing tank and thereby displacing the old could be as effective. The numbers ended up showing that there are marginal differences but that over time, they effectively equal out. So, when I built my new system, I engineered it to allow the "displacement" method. (Let me know if you want me to post images of the paper. It's pretty dry, but some might find it interesting.)

What I'm calling the "displacement" method is really the same as the automated systems that add and remove at the same time. I just don't see a need for 24-7 water changes on my system. I still prefer to be in the room when it happens. Sit back in my chair and watch the magic happen.
 

flagg37

Anthias
M.A.S.C Club Member
#6
I don't use constant water changes personally. However when I do conduct water changes, I add the new water to the display and open a valve on my sump which is located just above the normal water line. The new water obviously adds to the total system volume displacing water out of the sump and down the drain. I've grown to like this approach because I don't have to remove "X" gallons of water and replace with "X" gallons of new. It's a lazy approach but assuming the new water is well mixed in before reaching the sump, I have a very stable, low impact, but effective water change.

Back when I was at the University of Washington as an undergrad, I wrote a short paper comparing the two methods. I assumed that removing say, 20 gallons and then adding back in 20 gallons was the most effective way of exporting nutrients. I couldn't imagine that simply adding in new to the existing tank and thereby displacing the old could be as effective. The numbers ended up showing that there are marginal differences but that over time, they effectively equal out. So, when I built my new system, I engineered it to allow the "displacement" method. (Let me know if you want me to post images of the paper. It's pretty dry, but some might find it interesting.)

What I'm calling the "displacement" method is really the same as the automated systems that add and remove at the same time. I just don't see a need for 24-7 water changes on my system. I still prefer to be in the room when it happens. Sit back in my chair and watch the magic happen.
This is the same conclusion I came to as well. Of course the higher the percentage of water you’re changing out the less efficient it becomes but even up to like 20% it’s still negligible. Also, if where you add the water is farthest from where it drains you may not be losing any new salt water since it doesn’t instantly homogenize.
 

Dr.DiSilicate

Great White Shark
M.A.S.C Club Member
ex-officio
#7
I don't use constant water changes personally. However when I do conduct water changes, I add the new water to the display and open a valve on my sump which is located just above the normal water line. The new water obviously adds to the total system volume displacing water out of the sump and down the drain. I've grown to like this approach because I don't have to remove "X" gallons of water and replace with "X" gallons of new. It's a lazy approach but assuming the new water is well mixed in before reaching the sump, I have a very stable, low impact, but effective water change.

Back when I was at the University of Washington as an undergrad, I wrote a short paper comparing the two methods. I assumed that removing say, 20 gallons and then adding back in 20 gallons was the most effective way of exporting nutrients. I couldn't imagine that simply adding in new to the existing tank and thereby displacing the old could be as effective. The numbers ended up showing that there are marginal differences but that over time, they effectively equal out. So, when I built my new system, I engineered it to allow the "displacement" method. (Let me know if you want me to post images of the paper. It's pretty dry, but some might find it interesting.)

What I'm calling the "displacement" method is really the same as the automated systems that add and remove at the same time. I just don't see a need for 24-7 water changes on my system. I still prefer to be in the room when it happens. Sit back in my chair and watch the magic happen.
I’d read it...


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halmus

Registered Users
M.A.S.C Club Member
ex-officio
#8
Disclaimer 1: After I initially posted this back in 2012 (ish), a member of that local forum who I will just refer to as "d-bag" to hide his identity accused me of plagiarism. Evidently, someone had already presented something like this on a national site. Probably on Advanced Aquarist. I have never seen that article. However, this is like two independent people discovering the world is round simply because they had a question in their mind and the numbers presented the same outcome. That isn't plagiarism, that's science. I'm not comparing myself against any great thinkers in the scientific community; I'm just a blue collar hack today. So, I'm sure someone else already has a similar and much better written article on the same topic. Also, this isn't my effort to convince anyone to follow a certain methodology. I just thought it was an interesting thought experiment and was a little surprised by the outcome.

Disclaimer 2: This was based on a 120g tank I had at the time. Numbers don't match my tank today but the principles are the same.


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SynDen

Administrator
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#9
I really wanted to build my big tank with the displacement method, but since my basement didnt have a floor drain, and the only drain is high up on the wall, I have to pump out and replace with new instead. For that reason alone i heavily considered putting in a floor drain, that would cost a crazy amount to do, but couldnt bring myself to commit to that much. Maybe someday
 

halmus

Registered Users
M.A.S.C Club Member
ex-officio
#10
I really wanted to build my big tank with the displacement method, but since my basement didnt have a floor drain, and the only drain is high up on the wall, I have to pump out and replace with new instead. For that reason alone i heavily considered putting in a floor drain, that would cost a crazy amount to do, but couldnt bring myself to commit to that much. Maybe someday
Dual peristaltic pumps? Pumping in fresh and out the old simultaneously? If you’re OK with a slow water change.

I’ve considered that down the road so that I can move “used” water from my display to QT and from QT to the drain. Right now, I’m putting fresh mixed in QT during water changes and I like the idea of recycling (one way) the display tank’s water to the QT while still maintaining the separation. It would save on salt and my QT’s would benefit from the stability of the display’s water.

If I go that route, it will probably be the Apex DOS pumps as they already come in a pair and should be fairly well matched for flow rates.
 

TheRealChrisBrown

Reef Shark
M.A.S.C Club Member
ex-officio
#11
If I go that route, it will probably be the Apex DOS pumps as they already come in a pair and should be fairly well matched for flow rates.
I used my Dos for this purpose, it even has a pre-configured application for AWC. I found it to be really accurate via my crude ways of capturing the waste water in a bucket and emptying the bucket everyday...once I was satisfied it was accurate enough I directed the waste line to the drain. I got spooked when people started talking about double and triple redundancy which made me feel like a moron for having none. I felt like it was above my paygrade, I'm a simple plug and play guy. Only ran this for 8 weeks or so, but it seemed to work just fine at 2 gallons per day in and out.
 

neil82

Sting ray
M.A.S.C Club Member
#12
It's always interesting to hear different perspectives in favor of or against automation. I love hearing both sides. I'm all for automation when appropriate and with fail safes.
Regarding AWC- never tried it. Not saying I'm against it though. I'd need to design a system and then take some time to evaluate any potential issues that could arise and build in redundancy and real time monitoring to mitigate.
 

Dr.DiSilicate

Great White Shark
M.A.S.C Club Member
ex-officio
#13
It's always interesting to hear different perspectives in favor of or against automation. I love hearing both sides. I'm all for automation when appropriate and with fail safes.
Regarding AWC- never tried it. Not saying I'm against it though. I'd need to design a system and then take some time to evaluate any potential issues that could arise and build in redundancy and real time monitoring to mitigate.
That’s really why I asked the question. I think I actually like the interaction with the tank when I do water changes. I frag a couple things, check for healthy coral, use the turkey Bastet to stir the sand a bit... i don’t think I could be as successful without cleaning the detritus this way and automatically changing water wouldn’t replace it. Just an interesting topic.


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neil82

Sting ray
M.A.S.C Club Member
#14
That’s really why I asked the question. I think I actually like the interaction with the tank when I do water changes. I frag a couple things, check for healthy coral, use the turkey Bastet to stir the sand a bit... i don’t think I could be as successful without cleaning the detritus this way and automatically changing water wouldn’t replace it. Just an interesting topic.


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I would have to agree about water changing time being valuable in other ways. My ideal AWC system would probably be setup to change 10 gallons in an hour and I would turn it on manually using apex (nothing about this sounds automatic lol). I could do other maintenance on the tank during this time or just observe.
 

flagg37

Anthias
M.A.S.C Club Member
#15
I don't use constant water changes personally. However when I do conduct water changes, I add the new water to the display and open a valve on my sump which is located just above the normal water line. The new water obviously adds to the total system volume displacing water out of the sump and down the drain. I've grown to like this approach because I don't have to remove "X" gallons of water and replace with "X" gallons of new. It's a lazy approach but assuming the new water is well mixed in before reaching the sump, I have a very stable, low impact, but effective water change.

Back when I was at the University of Washington as an undergrad, I wrote a short paper comparing the two methods. I assumed that removing say, 20 gallons and then adding back in 20 gallons was the most effective way of exporting nutrients. I couldn't imagine that simply adding in new to the existing tank and thereby displacing the old could be as effective. The numbers ended up showing that there are marginal differences but that over time, they effectively equal out. So, when I built my new system, I engineered it to allow the "displacement" method. (Let me know if you want me to post images of the paper. It's pretty dry, but some might find it interesting.)

What I'm calling the "displacement" method is really the same as the automated systems that add and remove at the same time. I just don't see a need for 24-7 water changes on my system. I still prefer to be in the room when it happens. Sit back in my chair and watch the magic happen.
So where do you have the input and export on your system? In particular I’m wondering how the system handles a power outage since the water level in the sump will rise. Then when the power comes back on your ato will add whatever was displaced lowering the salinity.
 

halmus

Registered Users
M.A.S.C Club Member
ex-officio
#16
So where do you have the input and export on your system? In particular I’m wondering how the system handles a power outage since the water level in the sump will rise. Then when the power comes back on your ato will add whatever was displaced lowering the salinity.
I pump the freshly mixed saltwater into the display slowly. That mixes with the water column and eventually raises the water level in my sump. The water has to travel through much of the system to get to the export location. I have a bulkhead just above the water line in the sump near the return pumps. That runs through a ball valve and into the floor drain. The ball valve is closed at all times except when conducting water changes. It’s a manual operation. Nothing automated there. Otherwise it’s closed.

So, in the power outage scenario, the water level can rise significantly with no issue. The sump doesn’t know the bulkhead is there because the valve is shut. I do have an emergency overflow that leads to the floor drain so that the sump won’t overflow. That has been tested and water never rises that high. So, when the power is restored, water levels revert back to normal. ATO is handled through a toilet bowl plunger type float. That has been reliable in years of service. So, no change in salinity.
 

Andrew_bram

Tiger Shark
M.A.S.C Club Member
#17
I think you brought up good point. While doing an auto wc if always gets done I think you can gauge your tank a little better with a hands on approach

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dracus

Amphipod
M.A.S.C Club Member
#18
I don't use constant water changes personally. However when I do conduct water changes, I add the new water to the display and open a valve on my sump which is located just above the normal water line. The new water obviously adds to the total system volume displacing water out of the sump and down the drain. I've grown to like this approach because I don't have to remove "X" gallons of water and replace with "X" gallons of new.
I can't believe I haven't thought of this before, that's a great idea. One potential problem I can see is that you're not able to suck detritus and fish waste off of rocks or low flow areas like you're able to do with a siphon tube. I guess you could always siphon up that sort of buildup separately from your regular water changes though.
 

halmus

Registered Users
M.A.S.C Club Member
ex-officio
#19
You’re totally right that this method doesn’t lend itself well to a water change with a vacuum and detritus removal. It works well for just a straight forward water change but that’s about it.

I have a ton of flow in my tank which has been effective at keeping the crud off the rocks. But, my sand is probably 95% old fish poo. I’m not diligent with the vacuuming.
 
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