Apex DOS for Water Change - Disable ATO?

[bg2311]

New to the Apex scene and just ordered a DOS that I plan to use for incremental water changes over the course of a week (5-10%). For those of you using a DOS or otherwise for incremental automatic water changes, do you disable your ATO when the water changes are in progress to avoid triggering the ATO? Or does it not alter the water level because it's taking old water out at the same rate it's putting new water in negating a change in water level that would trigger the ATO to run?

I might be overthinking it. Right now our ATO is a homebrew Arduino with some relays and a Tunze pump.

 

[hzheng33]

yes, you need to pause the ato when doing water changes. if you don't...you will find the salinity decrease over time.

 

[bg2311]

As I understand it, the continuous water change function using the dual head DOS module (provided properly calibrated) will simultaneously draw from and replace water at the same rate, effectively avoiding a change in sump water level. The idea was to give it a volume of water to change each day (perhaps 1 gallon), and it would do so at spaced out small intervals over the course of the day. I haven't gotten to play with this function yet but our current ATO just uses a low level float switch to trigger.

If the fresh salt water reservoir ran dry, that would cause a drop in level. Adding a level sensor to it is probably a requirement to avoid that from happening.

 

[hzheng33]

will simultaneously draw from and replace water at the same rate, effectively avoiding a change in sump water level

not true. what you fail to consider is the evaporation at the surface of the water

so here's the thing: you take out 1 gal from the sump...put back in 1 gal....what about evaporation? evaporation is happening all day every day....some days more than the other....

 

[bg2311]

will simultaneously draw from and replace water at the same rate, effectively avoiding a change in sump water level

not true. what you fail to consider is the evaporation at the surface of the water

so here's the thing: you take out 1 gal from the sump...put back in 1 gal....what about evaporation? evaporation is happening all day every day....some days more than the other....

The ATO would still trigger when evaporation causes the level to drop and lowers the float switch. That's how it currently operates at least and runs through maybe 7 gallons in a week, topping the sump off many times in a given day. Water changes are currently entirely manual but the ATO just needs to be refilled about once a week. My concern was if the removing/adding of water with the continuous water change feature would cause enough of a fluctuation in sump level height to trigger the ATO float. I didn't realize that the Apex does this synchronously instead of removing, then adding it back. If water was being taken out first, then added back in, it would lower the level temporarily, potentially triggering the ATO depending on how much water was removed. If it's being removed and added in the same amount and at the same time, the water change at least wouldn't cause the level to change. You are right though that evaporation will still happen and the ATO will still be needed to avoid salinity creep. Drawing from one point in the sump and adding back into another portion (downstream) is probably how I will configure it. Finally will be able to fully utilize the tower I built a while back. Thanks for the feedback.

 

[lmm1967]

The ATO would still trigger when evaporation causes the level to drop and lowers the float switch. That's how it currently operates at least and runs through maybe 7 gallons in a week, topping the sump off many times in a given day. Water changes are currently entirely manual but the ATO just needs to be refilled about once a week. My concern was if the removing/adding of water with the continuous water change feature would cause enough of a fluctuation in sump level height to trigger the ATO float. I didn't realize that the Apex does this synchronously instead of removing, then adding it back. If water was being taken out first, then added back in, it would lower the level temporarily, potentially triggering the ATO depending on how much water was removed. If it's being removed and added in the same amount and at the same time, the water change at least wouldn't cause the level to change. You are right though that evaporation will still happen and the ATO will still be needed to avoid salinity creep. Drawing from one point in the sump and adding back into another portion (downstream) is probably how I will configure it. Finally will be able to fully utilize the tower I built a while back. Thanks for the feedback.

This is accurate as long as you set up the water change using the task in fusion - keep your DOS heads calibrated very well and this should work without issue. You won't need to alter your ATO.

 

[dan3949]

I have been using the DOS auto water change for about 1 year. I do nothing concerning my ATO. Auto water change adds and removes water at exactly the same rate (as long as DOS is properly calibrated), thus it does not impact your ATO. ATO is only triggered by evaporative losses. I check calibration 1/month. I also check salinity 1/month just to make sure everything is working properly. It is an absolutely fantastic system!

 

[bg2311]

I have been using the DOS auto water change for about 1 year. I do nothing concerning my ATO. Auto water change adds and removes water at exactly the same rate (as long as DOS is properly calibrated), thus it does not impact your ATO. ATO is only triggered by evaporative losses. I check calibration 1/month. I also check salinity 1/month just to make sure everything is working properly. It is an absolutely fantastic system!

Did you do anything to isolate the DOS heads for noise abatement? They're much larger motors than the dosing pump we currently use. Supposedly a bit noisy. I could probably put them inside the water change tower when I put the panels on it, maybe line the inside with some sound dampening foam.

 

[4nreefer]

During water changes, the DOS removes and adds the exact amount of water at the same time so it really shouldn't affect ATO. Now as a extra step, incase your pump is miscalliberated, you can turn off the ATO during water changes. However, if you do auto water changes, the DOS does the WC in small increments so you'll have to know the timing of the WC throughout the day to turn on and off your ATO (I personally didn't see the need for that). With reference to evaporation, AWC has nothing to do with evaporation. When evaporation happens, the ATO should refill the water level. I've been running mine for over a year with no issues.

Sent from my SM-G975U using Tapatalk

 

[dan3949]

Did you do anything to isolate the DOS heads for noise abatement? They're much larger motors than the dosing pump we currently use. Supposedly a bit noisy. I could probably put them inside the water change tower when I put the panels on it, maybe line the inside with some sound dampening foam.

No. I have the DOS mounted in a "fish room." The pumps are definitely louder than conventional dosing pumps (i.e. BRS dosing pump). In my opinion, it would be too loud to have the DOS mounted in the same room as your display tank. I don't know if mounting using foam/rubber to isolate noise/vibration would be effective. I don't think you would be happy with the noise level by just mounting on the water change tower. Remember, the DOS is a positive displacement pump and can easily move water a very long distance and height with no problem (this is true for both directions). Also, if you use the Fusion Quick Menu to setup up your schedule, the DOS will operate a few times every hour throughout the day to make the water change more "continuous." I change about 1 gallon/day. This equates to a 10% weekly change for my system. The DOS seems to run about 4 times per hour for about 2 minutes throughout the day/night. Find a place isolated from your tank (garage?) that you can put a large storage tank (2-3 week supply) put the DOS there. You really don't want the DOS in the same room as your tank.