Water changes using DOS

[Dibi]

Hi, I have a trick question here.

If we use DOS to do automatic water changes, and simultaneously we add NEW water and take out OLD water with the return pump on it did not mix the waters ?

I don't know if I was clear enough. But like, even if I take water close to my overflow and add new water in the return pump, the waters will mix. Right?

 

[rongy]

Not sure if I understand your question. I know a lot of people have high and low sensor, so they drain water until the low, and add fresh water until high. This way, you don’t have to constantly calibrate and match your in and out pump

 

[areefer01]

Look at this article. It may help you. Section 19 I believe is about auto water changes.

https://www.reef2reef.com/ams/neptune-apex-tutorials-part-9-dos.849/

 

[Rappa]

Hi, I have a trick question here.

If we use DOS to do automatic water changes, and simultaneously we add NEW water and take out OLD water with the return pump on it did not mix the waters ?

I don't know if I was clear enough. But like, even if I take water close to my overflow and add new water in the return pump, the waters will mix. Right?

Yes you are completely correct. I couldn't get past this as well, so I used a different schedule for removal and filling. I have the DOS set to remove 7000ml's of water from the system for 2 hours, then add 7000 ml's as soon as the removal time is complete. I do that twice a day for my system. 14,0000 ml's is roughly 3.7 gallons a day. You have to figure out what the max removal is for your system before the return pump starts to suck air and the pump starts to cavitate. It will send air bubbles into your display. My max rate of removal is 2 gallons, so I stay a little under it at 2,000ml's. I also have to put a code line into APEX for my ATK to shut off during water change times. For example... "IF TIME 10:00-14:00 THEN OFF". That is super important to have that time exactly input correctly, or you can swing salinity levels by ATK filling as your removing old water. Hope that helps!

 

[Dibi]

Yes you are completely correct. I couldn't get past this as well, so I used a different schedule for removal and filling. I have the DOS set to remove 7000ml's of water from the system for 2 hours, then add 7000 ml's as soon as the removal time is complete. I do that twice a day for my system. 14,0000 ml's is roughly 3.7 gallons a day. You have to figure out what the max removal is for your system before the return pump starts to suck air and the pump starts to cavitate. It will send air bubbles into your display. My max rate of removal is 2 gallons, so I stay a little under it at 2,000ml's. I also have to put a code line into APEX for my ATK to shut off during water change times. For example... "IF TIME 10:00-14:00 THEN OFF". That is super important to have that time exactly input correctly, or you can swing salinity levels by ATK filling as your removing old water. Hope that helps!

Perfect this way makes a lot more sense for me.

 

[Dibi]

Not sure if I understand your question. I know a lot of people have high and low sensor, so they drain water until the low, and add fresh water until high. This way, you don’t have to constantly calibrate and match your in and out pump

Yes, so you remove water and THEN you add the new one. Not at the same time. Right? that was my question, people do at the same time?

 

[Rappa]

Yes, so you remove water and THEN you add the new one. Not at the same time. Right? that was my question, people do at the same time?

I think "most" people do it at the same time for the convenience/time saving factor, also not knowing how to do it differently, as well as the sump water level factor. It can get tricky with ATK's screwing up the water change, but with the right coding you can do it pretty easily. You definitely have to calibrate your DOS pumps so they are exactly dead-on calibrated. For me, it also didn't make sense to mix the water as you are adding and removing. Essentially using 2 gallons of new salt water for every 1 gallon water change... that is just my rough calculations in my head and is no way "fact", but seems logical? Make sure to constantly check your salinity until you trust that your water changes are working properly. And you also want to set your max run time for your ATK to a low number, in case anything screws up, your ATK will error out and alert you before it just endlessly dumps R/O into the system. So, a few things to think about I guess....