DOS to change water between two tank simultaneously

[rds85]

I am debating if I can run two DOSs simultaneously to preform the following auto water change scheme:

DOS unit one to remove DT water and pump it to a small frag tank, as well as provide fresh new saltwater to DT. DOS unit 2 to remove water from the frag tank and into the waste water line, let the other side run blank or program this dos as normal dosing pump. This intended to have zero affects on ATO. I could space out the water removal of the frag system by a few minutes or exact same time. Theoretically this should work fine.

The frag tank is an AIO tank, which is on purpose if I need to run it as a stand alone system.
Display system: roughly 450 gallons
Frag system: 30 gallons

Concerns:
How long do these DOS actually stay in calibration?
Would you trust the this set up for long term, with standard maintenance on the pumps/tubing?
Has anyone done this successfully?

Benefits:
AWC of same DT water.
No need for biological filtration, heater or skimmer. Other mechanical can be debated.

 

[SuncrestReef]

As long as you have calibrated DOS1 and DOS2, your plan should work fine. I have had my DOS running auto water changes for over 2 years, and just recently I found the the salinity decreasing in my tank, and tracked it down to sediment buildup in my new saltwater line leading to the DOS. After flushing the line with citric acid, it cleared up and things are back on track. I'd simply recommend running a calibration every 6 months or so, and it should work fine.

 

[sdreef]

Would you be risking flooding if you add a larger volume than you remove from the frag system due to any mechanical or calibration issues that could occur with the second unit? I am wondering if your setup would put you at higher risk due to the difference in volumes of your display and frag system. I'm not sure how often and with what volume you are planning on running the water change or if you have some other safety measure in place, but something to consider.

I have been running the DOS for a small volume daily AWC for a couple months now. It has been working well, but too short of an experience to comment on calibration and more of a standard AWC set up with a single DOS unit.

 

[Poochaku]

I plan on running a similar system but using versas instead of the DOS. I believe this will be much better because the versas are rated for continuous duty thus you can use them for a continuous slow WC. This will hopefully keep the water level balanced between the addition and subtraction of water.

 

[rds85]

Would you be risking flooding if you add a larger volume than you remove from the frag system due to any mechanical or calibration issues that could occur with the second unit? I am wondering if your setup would put you at higher risk due to the difference in volumes of your display and frag system. I'm not sure how often and with what volume you are planning on running the water change or if you have some other safety measure in place, but something to consider.

I have been running the DOS for a small volume daily AWC for a couple months now. It has been working well, but too short of an experience to comment on calibration and more of a standard AWC set up with a single DOS unit.

Currently I run a daily 3 gallon water change on my system. The flooding concern can be combated with both an optical sensor and a leak detection sensor.

I also have not used the DOS system long term, so I am not sure the level of trust to give it.

 

[rds85]

I plan on running a similar system but using versas instead of the DOS. I believe this will be much better because the versas are rated for continuous duty thus you can use them for a continuous slow WC. This will hopefully keep the water level balanced between the addition and subtraction of water.

Honestly I have heard to many mixed reviews on versas. So unless the released a new version ( first gen is normally good but second gen is significantly better) I wouldn't use them. Kamora would be my choice.

 

[Breadman03]

I ran an AWC that way for a few years with no issues.

 

[rds85]

I ran an AWC that way for a few years with no issues.

Perfect good to hear I am not the only one and that someone had success.

 

[jonmos75]

I have mine plumbed exactly this way and have been running it like this for 3+ years with no issues.

 

[Opah]

I am debating if I can run two DOSs simultaneously to preform the following auto water change scheme:

DOS unit one to remove DT water and pump it to a small frag tank, as well as provide fresh new saltwater to DT. DOS unit 2 to remove water from the frag tank and into the waste water line, let the other side run blank or program this dos as normal dosing pump. This intended to have zero affects on ATO. I could space out the water removal of the frag system by a few minutes or exact same time. Theoretically this should work fine.

The frag tank is an AIO tank, which is on purpose if I need to run it as a stand alone system.
Display system: roughly 450 gallons
Frag system: 30 gallons

Concerns:
How long do these DOS actually stay in calibration?
Would you trust the this set up for long term, with standard maintenance on the pumps/tubing?
Has anyone done this successfully?

Benefits:
AWC of same DT water.
No need for biological filtration, heater or skimmer. Other mechanical can be debated.

I'm looking to do this right now. Did you ever implement it?

 

[SPS2020]

I'm looking to do this right now. Did you ever implement it?

I do this every Friday for a 9gal manual water change from my DT to a smaller 60g tank. Works well!

 

[rds85]

I'm looking to do this right now. Did you ever implement it?

Yes and I have been running it for years now

 

[GoodMoodley]

Yes and I have been running it for years now

So I am looking to do the same thing. I currently have a DOS on AWC from display to a bucket that I then manually change in to my frag tank every other day or so. I want to run a third dos head so I can send the output of the first DOS AWC system to the the frag tank and then run a third DOS head to remove the same amount of water from the frag tank to a drain.

I see SPS2020 is doing this on a manual Water Change cycle. Can the third DOS head be implemented as part of an Auto Water Change routine?

 

[rds85]

So I am looking to do the same thing. I currently have a DOS on AWC from display to a bucket that I then manually change in to my frag tank every other day or so. I want to run a third dos head so I can send the output of the first DOS AWC system to the the frag tank and then run a third DOS head to remove the same amount of water from the frag tank to a drain.

I see SPS2020 is doing this on a manual Water Change cycle. Can the third DOS head be implemented as part of an Auto Water Change routine?

Yes absolutely. I have had the third head doing this for multiple years now with no issues. Once ever 6-9 months you just might need to re calibrate, but they are never that far off from each other that it is concern, just monitor salinity on a monthly or bi monthly basis.

 

[SPS2020]

+1 on the occasional recalibration. Recently, I noticed that the tank downstream finished with too much water.

 

[GoodMoodley]

Yes absolutely. I have had the third head doing this for multiple years now with no issues. Once ever 6-9 months you just might need to re calibrate, but they are never that far off from each other that it is concern, just monitor salinity on a monthly or bi monthly basis.

How do I add a third head to the AWC routine?

 

[wickedxreef]

In theory this could work. you could add a safety optical sensor to the frag tank that if it reaches X height, it would kill the water change process.

Curious also, why pump to the frag system and not pull.

DOS 1 - Pull water from Salt mixing vat into Tank.
DOS 2 - head 1 pull water in from DT to FT and head 2 push water to drain.

If DOS 1 was to fail, it would only impact the main display. If DOS 2 fails, it wouldn't draw water in and push water out. Granted you can added additional optical sensors for safety measures as well.

 

[BillyW]

Y’all are way smarter than I am when it comes to this. I am getting ready to move back to the mainland and want to have two tanks setup using one sump. From what I am reading I could essentially just use one DOS to pull and push water from display tank into and out my second tank.
Display tank is about 120 gallons and second tank is around 20 gallons.
I want to do this to hide all the extra junk from the main tank so it looks clean. Calcium reactor and CO2 tank. As long as I have an optical sensor on the top of the 20 gallon tank it should work fine correct?