Salt declining

[Night Reefer]

I have notice that my salt is slowly going down down and down over time. I would have to add salt like every two weeks. Any help would be great. I do no water changes as I am following the triton method. I do remove about a gallon every two weeks but the gallon removed wouldn’t drop me from 36 ppm to 34 ppm in a two weeks time. I also notice a fluctuation daily and I am concerned it’s too wide of a gap. See apex screen shot below.

 

[Larry L]

You might be seeing fluctuations that correspond to temperature changes. Conductivity measurement and calibration is very sensitive to temperature. Make sure you have temperature compensation turned on for your conductivity probe in your Apex setup.

Here's an old thread so not sure if the instructions are still the same, but it's the same idea: https://www.reef2reef.com/threads/2016-neptune-apex-salinity-probe-readings.271479/

Also FWIW even if you do not do water changes, conductivity can change due to evaporation, loss of water in your skimmer cup, salt creep, etc.

 

[Night Reefer]

You might be seeing fluctuations that correspond to temperature changes. Conductivity measurement and calibration is very sensitive to temperature. Make sure you have temperature compensation turned on for your conductivity probe in your Apex setup.

Here's an old thread so not sure if the instructions are still the same, but it's the same idea: https://www.reef2reef.com/threads/2016-neptune-apex-salinity-probe-readings.271479/

Also FWIW even if you do not do water changes, conductivity can change due to evaporation, loss of water in your skimmer cup, salt creep, etc.

I have very little to none on the salt creep and I was told by apex that shouldn’t turn on temp comp. skimmer has been off due to the fact I removed all nitrate and all phosphate. Need to bring the levels up a bit. Also my refracometer matches the probe.

 

[Larry L]

You're not supposed to turn on temperature compensation unless you have a temp probe connected to the same PM module that your conductivity probe is connected to, so that might be the reason that they told you not to turn it on. But if you don't have a probe connected and don't turn on temp compensation, then you could see the variations that you are seeing.

I assume you do have an Apex temp probe in your setup, and if you do it's probably connected to your Apex base unit. Try selecting "Compare" and see how the salinity graph looks compared to your temp graph (assuming the two probes are physically located relatively close to each other in the tank or sump). If they look like they follow the same pattern, you might want to think about moving the temp probe from the base unit to the same PM module as the conductivity probe and then turning on the temp compensation.

 

[MnFish1]

Have you verified the measurements from the apex to a calibrated refractometer? The 'variation' you see during the day can't be the actual 'salinity' it has to be the device you're measuring with.

 

[MnFish1]

Have you verified the measurements from the apex to a calibrated refractometer? The 'variation' you see during the day can't be the actual 'salinity' it has to be the device you're measuring with.

also - how big is your tank?

 

[Randy Holmes-Farley Verified Community Expert]

Over time, skimming removes salt water and if you replace it with fresh, salinity will decline.

On the other hand, using a two or three part calcium and alkalinity system slowly boosts salinity.

 

[Night Reefer]

• 
  I do have the full apex system. Had trouble with the probe at the start and support worked it out with me on the phone. Both probes are next to each other. They told me the Turing on the temp think under the salt would cause more issues and better to leave it off. Measurements on the refractometer are the same as the probe .its a 180 g tank with a 60 g sump. Currently I’m not doing any dosing as all my levels are good or higher than needed to be. I do have about eight corals LPS, SPS,stony and some scallops. Skimmer is currently off due to the fact my nitrate and phosphate levels are at zero so I’m trying to bring those levels up a bit. The system is now running in the low 34 range

 

[MnFish1]

• 
  I do have the full apex system. Had trouble with the probe at the start and support worked it out with me on the phone. Both probes are next to each other. They told me the Turing on the temp think under the salt would cause more issues and better to leave it off. Measurements on the refractometer are the same as the probe .its a 180 g tank with a 60 g sump. Currently I’m not doing any dosing as all my levels are good or higher than needed to be. I do have about eight corals LPS, SPS,stony and some scallops. Skimmer is currently off due to the fact my nitrate and phosphate levels are at zero so I’m trying to bring those levels up a bit. The system is now running in the low 34 range

So are you saying that lets say you checked with a refractometer on June 20 at the high point it would register 35.2 (1.0265) and at the low a couple minutes later on June 20 34.1 (1.0257)....? My guess is that these are so small that it would be difficult to see on a refractometer. The changes are probably not significant and represent variation in measurement. Even looking at your first picture you posted, the high on June 15 (35.8 =1.027) to the low of June 21 (34.4 = 1.026) *and that was only 1 spike downward... there is not much difference. The picture does look like a trend down. but it would be good to have more data over more days.

 

[Night Reefer]

The trend continues as days pass. When it breaks the 34 level I mix up 4 cups or so and toss it in wither a day the levels slowly go up to 36. I added more salt about 2 weeks ago to bring the levels up. Yes the levels are to small to see on the refractometer, so I test it at the high and low levels only as a precaution.

 

[Night Reefer]

June 14 - June 21

 

[Fishfinder]

How close is your conductivity probe to your ATO line? My salinity does the same when my ATO comes on

 

[MnFish1]

June 14 - June 21

So if you take the mean value on 6/14 of about 35.4 (1.0267) and the mean value on 6/21 34.75 (1.0262). there is really no difference - is there? If you take the absolute high (35.8 = 1.027) and the absolute low 34.1 (1.0258) you would barely notice this if you were testing with a refractometer. The interesting thing is that a very short time after the absolute low, the Salinity was back up to 35.1 = 1.0264. I don't think any of these values are significantly different - and probably represent 'noise' or water added to the system (food? additives?) or salt being lost from the system (splash, etc) But seems the likelihood is that it relates to the way its being measured rather than something you can 'fix'

 

[Night Reefer]

The issue really is not the fluctuation as it seems close enough. I would have thought to see a gradual decline or incline. More so the drop over time. I have not taken any water out of the tank in the last week or so. I will report numbers again in a few days. The only salt build up I have is on the screen mess cover. I clean this once a week with a wet cloth and push it back into the tank.

 

[Night Reefer]

How close is your conductivity probe to your ATO line? My salinity does the same when my ATO comes on

Separate tank 3 feet away

 

[Randy Holmes-Farley Verified Community Expert]

Salinity cannot just drift down. Salt must be removed or water added. [emoji3]

 

[Night Reefer]

Separate tank 3 feet away

Salinity cannot just drift down. Salt must be removed or water added. [emoji3]

totally agreed

 

[Victoria M]

A leak somewhere and the ato is topping off for the loss?

 

[MnFish1]

Based on the graph I see the salinity is not dropping it’s going up and down randomly with a variance of .001 which is not significant over a 4 day period. Jmho

 

[reefwiser]

Another reason why one doesn’t use a salinity probe for anything. [emoji3]
Best to use a refractometer than a probe. You are getting false readings. Found this out years ago when I first started using one. Not a useful probe so stopped messing with it all the time. Just do it by eye now much better.