Placement of auto top off sensor?

[Eggpaul]

Where is the best place to put the sensor in the sump? At the return, or drain area?

 

[Dr. Reef Verified Sponsor]

at the return section at the level where you would normally keep water at running position.

 

[Alfrareef]

Plus one on the return!

 

[sbidny]

The sump baffle will keep the area on the drain side a consistent height. Therefore, you must place the sensor on the return side, which is where the effects of evaporation will be realized. If you watch your sump without the ATO installed, you should see the level on the return side fall as the water evaporates.

 

[Eggpaul]

The sump baffle will keep the area on the drain side a consistent height. Therefore, you must place the sensor on the return side, which is where the effects of evaporation will be realized. If you watch your sump without the ATO installed, you should see the level on the return side fall as the water evaporates.

Lol, now it makes sense. So if I add water to the drain side it doesn't rise up? It would raise the level in the return portion?

 

[Eggpaul]

The sump baffle will keep the area on the drain side a consistent height. Therefore, you must place the sensor on the return side, which is where the effects of evaporation will be realized. If you watch your sump without the ATO installed, you should see the level on the return side fall as the water evaporates.

Also, I felt like when I added water in the sump the level in the overflow box went up also. Am I correct?

 

[redfishbluefish]

The only change in water level should be noted in the return section only. All other areas of the sump, the water level is defined by the height of the baffles. The return section should have water "cascading" over that last baffle into that area. That's were the sensors go to maintain that level in that return area.

I have no idea why water level would change in the overflow.

 

[sbidny]

Lol, now it makes sense. So if I add water to the drain side it doesn't rise up? It would raise the level in the return portion?

Correct. However, if you add more water than the height of the baffle, the drain side will start to rise as well, which is generally undesirable. You want a consistent height in the drain side for things like your skimmer, which benefit from the consistency in height.

Ideally, the water should cascade just a little over the baffle into the return side. This is the height you want to place your sensor.

Then you'll want to test shutting off your return pump to ensure that your sump can accommodate the extra water that will fill it when the return is off. Be prepared to turn your return pump back on if it appears it's going to overflow. If this is the case, you can try lowering your ATO sensor a bit and removing some water to make a bit more room in the sump. Then test again.

 

[sbidny]

Also, I felt like when I added water in the sump the level in the overflow box went up also. Am I correct?

This generally shouldn't be the case, in my experience.

However, if you increase the flow from your return pump, the water level in the tank will rise a bit, and you may see the water in the overflow box go up as well. If the level in the return section was very low, it could be that raising it allowed your return to flow a bit more, but that should have minimal effect.

What kind of overflow are you running? Is it a external box that hangs off the tank?

 

[Eggpaul]

This generally shouldn't be the case, in my experience.

However, if you increase the flow from your return pump, the water level in the tank will rise a bit, and you may see the water in the overflow box go up as well. If the level in the return section was very low, it could be that raising it allowed your return to flow a bit more, but that should have minimal effect.

What kind of overflow are you running? Is it a external box that hangs off the tank?

It's a built in overflow box in the center. Using durso with emergency. No sound at all.

 

[Eggpaul]

Correct. However, if you add more water than the height of the baffle, the drain side will start to rise as well, which is generally undesirable. You want a consistent height in the drain side for things like your skimmer, which benefit from the consistency in height.

Ideally, the water should cascade just a little over the baffle into the return side. This is the height you want to place your sensor.

Then you'll want to test shutting off your return pump to ensure that your sump can accommodate the extra water that will fill it when the return is off. Be prepared to turn your return pump back on if it appears it's going to overflow. If this is the case, you can try lowering your ATO sensor a bit and removing some water to make a bit more room in the sump. Then test again.

Using a Hydor ato set up that I used in my biocube 29 for years. A little hard to get it right on. For some reason after it filled it to the correct height, I got an alarm about 25 min later because the return level water had risen. Why would this happen?

 

[Eggpaul]

The only change in water level should be noted in the return section only. All other areas of the sump, the water level is defined by the height of the baffles. The return section should have water "cascading" over that last baffle into that area. That's were the sensors go to maintain that level in that return area.

I have no idea why water level would change in the overflow.

Why does the water from the fuge have to cascade into the return? What is the benefit of that? What would happen if it's like this? Only reason it's like that now is because the pump is off, I'm doing a water change. Just wondering what are the benefits of a cascade.

 

[redfishbluefish]

That photo isn't telling me anything. What I'm saying is that when your pump is on, the water level in the return section needs to be below that lower baffle on the right for the ATO to work.

 

[Eggpaul]

That photo isn't telling me anything. What I'm saying is that when your pump is on, the water level in the return section needs to be below that lower baffle on the right for the ATO to work.

Yes it is. Thanks.