Salinity keeps dropping!

[cnjcpb]

This is the second time my salinity has dropped from 1.025 to 1.022. Is it my ato!? I do skim wet and dump my cup often. Could this be the problem?

 

[tzabor10]

Certainly

 

[Cell]

Minimal info here. What kind of time frame are we talking about and can you estimate how much water you are removing via skimmer or other?

 

[JNalley]

Skimming wet removes the volume of saltwater that is your skimmer cup every time you do it. If your saltwater isn't being replaced, and instead you're just allowing the ATO to add RO to replace the lost saltwater, then you're definitely lowering the salinity gradually over time.

I do agree with @Cell though, we don't have enough information here to help you make informed decisions.

How (and how often) are you testing salinity? Hydrometer, Refractometer, Conductivity Probe?

Over what period is the Salinity dropping? Daily? Weekly? Monthly?

How (and how often) are you calibrating your chosen Salinity tester?

Is your tank temperature stable (within 1 degree in either direction)?

The answers to the above questions will give us a more detailed picture.

 

[cnjcpb]

Skimming wet removes the volume of saltwater that is your skimmer cup every time you do it. If your saltwater isn't being replaced, and instead you're just allowing the ATO to add RO to replace the lost saltwater, then you're definitely lowering the salinity gradually over time.

I do agree with @Cell though, we don't have enough information here to help you make informed decisions.

How (and how often) are you testing salinity? Hydrometer, Refractometer, Conductivity Probe?

Over what period is the Salinity dropping? Daily? Weekly? Monthly?

How (and how often) are you calibrating your chosen Salinity tester?

Is your tank temperature stable (within 1 degree in either direction)?

The answers to the above questions will give us a more detailed picture.

I figured it out. It’s definitely me messing with the filter compartments. I keep messing with the configuration and the water level will rise in the filter compartments. I will pull out a couple 40 ml scoops and dump to get the water level where I want it. Then the ATO tops off with fresh. I didn’t know removing SW would lower salinity if I use ATO. Figured taking sw out, then letting ATO top off at new level wouldn’t raise salinity.

 

[Manpeckz]

Sounds like it’s a matter of where you need your ATO sensor placed. But at least you realized the problem, only top off evaporated water.

 

[Cell]

Whenever saltwater is manually removed and is replaced by freshwater, you are lowering salinity. You are removing water+salt and replacing it with just water.

ATO is used to replace saltwater that has evaporated, water evaporates but the salt stays behind in this case, which concentrates salt content increasing salinity until an equal amt of freshwater is added.

 

[crazyfishmom]

This is the second time my salinity has dropped from 1.025 to 1.022. Is it my ato!? I do skim wet and dump my cup often. Could this be the problem?

How big is your tank? How frequently do you have to refill your ATO? How are you measuring salinity?

 

[cnjcpb]

How big is your tank? How frequently do you have to refill your ATO? How are you measuring salinity?

26 gallon AIO - measure with refactor every other day. I go through about 4 gallons a week of RO.

 

[LPS_guy]

Your refractometer could be off

 

[cnjcpb]

Your refractometer could be off

I calibrate it every time I check. LFS also confirmed.

Your refractometer could be off

yeah. I have to calibrate every time I use it.

 

[cnjcpb]

Whenever saltwater is manually removed and is replaced by freshwater, you are lowering salinity. You are removing water+salt and replacing it with just water.

ATO is used to replace saltwater that has evaporated, water evaporates but the salt stays behind in this case, which concentrates salt content increasing salinity until an equal amt of freshwater is added.

Yes, but shouldn’t salinity stay the same if I remove two quarts and move the sensor to the new level?

 

[Dom]

FYI:

Water evaporates, not salt. This is why we top off with RODI; to replace water that has evaporated.

If you are dumping wet skim, you are removing both water and salt. So I would think that would contribute to your issue.

Did you happen to notice if there is a leak anywhere? A leak will have the same effect because you are losing both water and salt, but only topping off with water.