Should I be doing automatic water changes?

[xaflatoonx]

What about the genesis system. It’s pricey - but looks pretty epic in that it literally thinks of everything. Plus it’s a standalone setup that doesn’t take any resource away from a doser.

 

[GK3]

What food is your afs dropping in the sump that makes it through the return pump? I didn’t think this would work.

 

[Belgian Anthias]

Automated daily water changes and automated daily evaporation correction. How keep the correct salinity?

 

[Randy Holmes-Farley Verified Community Expert]

Automated daily water changes and automated daily evaporation correction. How keep the correct salinity?

The automatic water changes are typically slow and on a timer, with in and out at the same time, so the water level does not change.

 

[Belgian Anthias]

The automatic water changes are typically slow and on a timer, with in and out at the same time, so the water level does not change.

Not very effective as new added water may be partially removed ?
As the level does not change the evaporation must be automated using EC?

 

[Randy Holmes-Farley Verified Community Expert]

Not very effective as new added water may be partially removed ?
As the level does not change the evaporation must be automated using EC?

It is a tiny bit less effective than out then in. Continuous changes this way amounting to 30% changed is equivalent to one 26% water change, out then in.

There is no effect on evaporation replacement choices and methods. If there is evaporation, the level declines in the sump or tank as usual. The water change method, when done in and out at the same time by itself does not alter whatever the water level is.

 

[shred5]

I want to do daily small automatic water changes on my new build.

 

[Ardeus]

Has anyone tested the water in the container a week after mixing? Do you guys choose the salt taking these changes into account? I think I remember BRS stating that these changes were really significant in the majority of salt brands.

 

[Belgian Anthias]

It is a tiny bit less effective than out then in. Continuous changes this way amounting to 30% changed is equivalent to one 26% water change, out then in.

There is no effect on evaporation replacement choices and methods. If there is evaporation, the level declines in the sump or tank as usual. The water change method, when done in and out at the same time by itself does not alter whatever the water level is.

26% instead of 30%?
Depending of where the water is removed and added? And the water temperature is the same as water with a different temp may not mix directly and form new water layers which may be removed the moment it is added?

A water change of 30%, is 30% of the water removed and replaced after removal, effectiveness = 100%.
Remove 30% of the total water volume ( a mixture of old and new) in a certain time span and during the same time add the same volume new water, is not a water change of 30% but a water transfer between a mix of old and new and new water!
26%? How this was calculated? It seems to me not possible to have an effectiveness of 86% this way.
The transfer rate (time x flow) is probably the main factor for calculating the effectiveness?

 

[Ernie Krulikowski]

Has anyone tested the water in the container a week after mixing? Do you guys choose the salt taking these changes into account? I think I remember BRS stating that these changes were really significant in the majority of salt brands.

I use rscp fresh mix alk is around 11.5 at end of week when it’s time to refill holding vat it’s at 8.5 . But alk level in display isn’t affected. Dose 100 ml of alk daily and tanks always at 8.5. 328 gallon tank 5 gal per day awc

 

[jwt1603]

I’m not trying to sell anything but I bought one of those auto aqua ato/awc and I don’t think I will ever not have a auto water change again. 75 gal display with a 30 gal dump and I have it doing 1 gallon change every 12 hours. I absolutely love it.

I use the same ATO / AWC set up on my Red Sea tank, 108 in the display and 31 in the sump. I love it. I change about a gallon and a half every day. I love the way you can adjust the refill time so you don't just dump a bunch of new cold water in there once a week or so. My water chemistry stays level all the time. And with the ATO built into it it takes away another routine task. Saving that time gives me more time to do other maintenance items, and more time to look at the tank and enjoy it.

 

[reefwiser]

I have been tempted by automatic water changes but I am always put back because of the change in the parameters when you store the water for too long. Some salts are only usable for 24 hours after mixing!

How do you guys cope with that?

I mix up a weeks worth of salt at a time and I use high grade salt ESV. I found that using lower grade salt would coat my "fresh " salt water lines with brown gunk.

I’m not trying to sell anything but I bought one of those auto aqua ato/awc and I don’t think I will ever not have a auto water change again. 75 gal display with a 30 gal dump and I have it doing 1 gallon change every 12 hours. I absolutely love it.

I just don't like to have all my eggs in one water change basket. I used industrial pump that I work with here at work and know how worry free they are and simple to use. These premade units just scare me ,but Hey I am and old industrial maintenance man I like things that I can trust to not break down on me at the wrong time.:)

 

[jwt1603]

The Auto Aqua ATO / AWC shuts off the ATO function when it goes into AWC mode so there's no mix up of the ATO seeing a low water level and kicking in fresh water. You can adjust how often it does the water change, once a day, every other day, every hour, every two hours, every 10 minutes, etc. Pretty much what ever you want. The optical sensors in the sump return area allow you to adjust how much water it takes out. The sensors shut off the AWC drain pump when the water level drops to the set level. You pre-select a refill cycle time. I have mine set to pump for 10 seconds then wait 200 seconds, pump for 10, wait 200. Takes quite a while to bring the level back up but it's in the return pump side of the sump and doesn't impact the tank water level. The long refill time allows the new water to mix in with the existing tank water very, very slowly. I would think that equates to less shock to the system and it would blend easier with the water still in the tank. I'm not a salt water chemistry genius by any means but it sort of seems logical that refilling it slowly would be better.

I have three water containers. One for fresh ATO water, one for new AWC salt water, and one for waste salt water. The containers are covered and in a closet that happens to be right behind the living room wall the tank is on so it was easy to cut a hole through behind the stand and run the lines between the tank and containers. New water goes into the containers about every other day or so. I could go longer if needed, like this weekend when we will be out of town. Waste water gets dumped as needed.

Full disclosure here. It was my wife that came up with the idea of cutting the hole in the wall (of our new house) and putting the containers in the closet. She saw me trying to figure out how to have the containers close to the tank in the living room without it looking stupid. When she asked what I was thinking about she immediately said to just cut the hole and be done with it. Light bulb goes on.

 

[Randy Holmes-Farley Verified Community Expert]

26% instead of 30%?
Depending of where the water is removed and added? And the water temperature is the same as water with a different temp may not mix directly and form new water layers which may be removed the moment it is added?

A water change of 30%, is 30% of the water removed and replaced after removal, effectiveness = 100%.
Remove 30% of the total water volume ( a mixture of old and new) in a certain time span and during the same time add the same volume new water, is not a water change of 30% but a water transfer between a mix of old and new and new water!
26%? How this was calculated? It seems to me not possible to have an effectiveness of 86% this way.
The transfer rate (time x flow) is probably the main factor for calculating the effectiveness?

The calculations assume perfect mixing, and the “mixed tank” is a standard problem in differential equations, but it is easily simulated with excel. Suppose you did 300 changes of 0.1%, the effective amount changed is just 0.999^300 = 26% changed.

I can actually attain slightly better than the stated 26% if I draw the old water out upstream of the new water being added.

I discuss these issues here and compare different types of changes:
http://reefkeeping.com/issues/2005-10/rhf/

 

[Randy Holmes-Farley Verified Community Expert]

Has anyone tested the water in the container a week after mixing? Do you guys choose the salt taking these changes into account? I think I remember BRS stating that these changes were really significant in the majority of salt brands.

I never worried about it and in many reef tanks the contribution to alk dosing or demand from water changes is small, but if you use a very high alk mix and have naturally low alk demand in the tank, it might be an issue.

With a tank at 8 dKH and new water at 11 dKH, the boost to alk is only 0.03 dKH per day when changing 1% daily. Whether that drops to none seems too small to worry about for many tanks that consume ten to a hundred times more than that each day.

 

[Blz14me1]

I use the same ATO / AWC set up on my Red Sea tank, 108 in the display and 31 in the sump. I love it. I change about a gallon and a half every day. I love the way you can adjust the refill time so you don't just dump a bunch of new cold water in there once a week or so. My water chemistry stays level all the time. And with the ATO built into it it takes away another routine task. Saving that time gives me more time to do other maintenance items, and more time to look at the tank and enjoy it.

I couldn’t agree more

 

[Blz14me1]

I mix up a weeks worth of salt at a time and I use high grade salt ESV. I found that using lower grade salt would coat my "fresh " salt water lines with brown gunk.

I just don't like to have all my eggs in one water change basket. I used industrial pump that I work with here at work and know how worry free they are and simple to use. These premade units just scare me ,but Hey I am and old industrial maintenance man I like things that I can trust to not break down on me at the wrong time.:)

I understand exactly what your saying. I’m a piping guy that does industrial maintenance. I am always worried something’s going to malfunction. Thank fully so far it has not. I have my old water pumped into a bucket instead of the drain, it causes me to empty the bucket every 2 days but this way I can physically look and see what has or has not happend with the water change out.

 

[reefwiser]

I have a waste buck that fills up and I can watch it rise. I then know to change out the fresh water. I can automate it more with a float switch but I makes me watch my water so I have kept it this way.
One needs to keep a watch on their tank one way or another. While auto water change is nice it really hasn't changed my maintenance routine that much I still have to keep the tank clean. I am setting up a canistrer filter now with filter pads so I can vacuum the tank bottom ( currently running bare bottom) I also try and runs my marineland diatom filter every couple of weeks to keep things clean. Changing water is one thing and keeping the tank clean is another.

 

[Belgian Anthias]

The calculations assume perfect mixing, and the “mixed tank” is a standard problem in differential equations, but it is easily simulated with excel. Suppose you did 300 changes of 0.1%, the effective amount changed is just 0.999^300 = 26% changed.

I can actually attain slightly better than the stated 26% if I draw the old water out upstream of the new water being added.

I discuss these issues here and compare different types of changes:
http://reefkeeping.com/issue2005-10/rhf/

10 ppm nitrate in a tank.

A 30% water change at 100% with nitrate free water will bring the level to +- 7ppm
According to the above equation the nitrate level will become +- 7.4 ppm

According to my estimation the level will become +- 7.45ppm, which is about the same. ( 30% water transfer)

Assume perfect mixing.
A 30 % water transfer. At start 100% old water is removed and 100% new added. When the transfer stops the removed water is a mix of 70% old and 30% new. The removed water will contain an average of 15% newly added water. For a 1000l tank this means that when 30% new water is added +- 45 litre is wasted.

For a 50% water transfer +- 25% of the newly added water will be wasted. This is only an estimation, not a correct calculation. A lot of good water wasted!!
The bigger the water change the more water is wasted when this method is used.?

 

[d2mini]

Over the years I've setup and run AWC several ways on different tanks.
On my current tank, I just went back to using dual level sensors and two pumps. One regular hobby pump in the sump to remove the old water, one peristaltic pump to add the new water.
Here's why... calibration.
I've tried it with meter liter pumps, GHL Doser 2.1, and masterflex pumps. For whatever reason, I had the best success with the LiterMeter setup.
But with any of them, the two pumps HAVE to be calibrated exactly equal, otherwise you end up with salinity shifts. If you don't pump enough back in, your ATO will kick on and finish with RO water causing you salt level to drop over time. If you put too much back in, your salt level will creep up. With the level sensors, the exact amount of water you remove is replaced. No calibration needed.

GHL has had AWC programming built into their controller for years and years and this is the way they've always recommended doing it.
Trust me... they are right! ;)
Dosing pumps can be calibrated equally if you are lucky but even then it can change over time. Why deal with the hassle?