Salinity jumped from 35 to 40 during one hour

[Ani_28]

Hi.

I have 13 gallons aquarium. Now it’s 7 months.
On Saturday I cleaned sand and changed 50% of water. I had 2 shrimps during 2 months and 2 clown fifth one week. One fish was very nervous in the 9 pm, I changed 10% of water. I checked salinity at 6 pm it was 35. In the morning one fish was alive. Salinity was 40. I made it 35( add some new 10% of water and osmosis). In one hour salinity was 40 again.

Temperature 76-77, pH dropped from 8 to 7.5, NH3- 0.25, NO2- 0, NO3- 5.0
These parameters stable all the time except pH, that dropped in the morning

 

[Ziggy17]

What are you testing salinity with?

 

[redfishbluefish]

What are you using to measure salinity?

 

[Ani_28]

What are you using to measure salinity?

Refractometer

 

[Ziggy17]

Refractometer

Try zeroing it with RO water, then measure the tank water again. Salinity doesn’t jump like like.

If you search the threads here, there’s also a 35ppm refractometer calibration solution recipe you could use as well.

 

[Ani_28]

Thank you.
But it really happened

 

[Asm481]

There are two ways salinity will increase. Either you added salt, maybe knocked in some salt creep from the side of the tank. Or you have a lot of evaporation because the water evaporates leaving a higher salt concentrations.
Maybe you are not measuring accurately. Using a swing arm hydrometer can be difficult sometimes getting it bubble free.
Smaller tanks vary much more. Hope you're running an auto top off. They are life savers in my opinion.

 

[W31Olds]

Not possible unless you had absolutely no humidity and evaporated a large amount of water overnight. And I would imagen you would have noticed the water level was significantly lower.

 

[Ziggy17]

There are two ways salinity will increase. Either you added salt, maybe knocked in some salt creep from the side of the tank. Or you have a lot of evaporation because the water evaporates leaving a higher salt concentrations.
Maybe you are not measuring accurately. Using a swing arm hydrometer can be difficult sometimes getting it bubble free.
Smaller tanks vary much more. Hope you're running an auto top off. They are life savers in my opinion.

Salt creep won’t increase salinity that much 8n a 13 gallon.

He’s not using a swing arm hydrometer.

No way it’s evaporating that much overnight.

It’s likely a measurement error.

 

[Ani_28]

There are two ways salinity will increase. Either you added salt, maybe knocked in some salt creep from the side of the tank. Or you have a lot of evaporation because the water evaporates leaving a higher salt concentrations.
Maybe you are not measuring accurately. Using a swing arm hydrometer can be difficult sometimes getting it bubble free.
Smaller tanks vary much more. Hope you're running an auto top off. They are life savers in my opinion

Salt creep won’t increase salinity that much 8n a 13 gallon.

He’s not using a swing arm hydrometer.

No way it’s evaporating that much overnight.

It’s likely a measurement error.

Water was prepared on Saturday and during half of that day and Sunday salinity keeper 35

 

[Ani_28]

Not possible unless you had absolutely no humidity and evaporated a large amount of water overnight. And I would imagen you would have noticed the water level was significantly lower.

Water level was on good position. I checked it at first

 

[Seven Year Nap]

The only way I could see this happening is if you measured your salinity of "new" water before all the salt actually dissolving.

When you mix up salt water, are you weighing everything out or are you just adding salt and mixing a bit before testing salinity, and then adding more if needed?

If you had a bunch of undissolved salt in your new water, measured the salinity at 35 and then added it to your tank, all of the undissolved salt will continue to dissolve and raise your salinity.

I only ask because you said you did a 50% water change which may be more than you normally do and so you rushed through mixing up the salt water.

 

[Ani_28]

The only way I could see this happening is if you measured your salinity of "new" water before all the salt actually dissolving.

When you mix up salt water, are you weighing everything out or are you just adding salt and mixing a bit before testing salinity, and then adding more if needed?

If you had a bunch of undissolved salt in your new water, measured the salinity at 35 and then added it to your tank, all of the undissolved salt will continue to dissolve and raise your salinity.

I only ask because you said you did a 50% water change which may be more than you normally do and so you rushed through mixing up the salt water.

Yeah, I checked several times before I add new water. And salt was mixed 5 hours before I started to check.

 

[Ziggy17]

The only way I could see this happening is if you measured your salinity of "new" water before all the salt actually dissolving.

When you mix up salt water, are you weighing everything out or are you just adding salt and mixing a bit before testing salinity, and then adding more if needed?

If you had a bunch of undissolved salt in your new water, measured the salinity at 35 and then added it to your tank, all of the undissolved salt will continue to dissolve and raise your salinity.

I only ask because you said you did a 50% water change which may be more than you normally do and so you rushed through mixing up the salt water.

Or measured the mix at 35 when the water was well below 77 degrees giving a false reading of 35

 

[Ziggy17]

Yeah, I checked several times before I add new water. And salt was mixed 5 hours before I started to check.

Did you heat the water to 77 before the final salinity check?

 

[Ani_28]

Or measured the mix at 35 when the water was well below 77 degrees giving a false reading of 35

Thank you

 

[Biokabe]

There aren't very many ways for salinity to increase. Basically, either evaporation, unintended dosing, topping off with saltwater, or measurement error.

Given that one of your fish died, it's possible that there really was a rapid increase in salinity.

I'm not trying to be rude here, but the sequence of events isn't completely clear, so I'm going to rephrase it in my own words and please let me know if I have it right.

On Saturday, you cleaned the sand. Why did you clean the sand, and how did you do it?

After cleaning the sand, you performed a 50% water change.

At 6 PM, you checked the salinity and it measured as 35 (I assume you're using Parts Per Thousand and not Relative Specific Gravity).

After the water change, you noticed that one of your fish was distressed, and you did a 10% water change.

When you checked in the morning, one of your fish (the same one that was distressed?) was dead, and salinity measured 40 at that point.

Here I'm not entirely clear. You say you added 10% new water plus mixed in some osmosis water. Did you add extra salt water, or did you change 10% of the water and then mix in some osmosis to your tank to correct the salinity to 35?

After an hour, your salinity was once again at 40. In this same time frame, your pH dropped from 8.0 to 7.5.

How quickly did you mix up the saltwater? What's your procedure for making sure it's correct?

I think @Seven Year Nap might be on to something. Assuming everything you've said is accurate and you didn't have a measurement error, the only way for salinity to increase would be for something to dissolve in your water. Could be undissolved salt, could be precipitate in the tank dissolving in the lower pH.

 

[Ani_28]

Did you heat the water to 77 before the final salinity check?

yes

 

[Seven Year Nap]

Or measured the mix at 35 when the water was well below 77 degrees giving a false reading of 35

I believe a lower temp results in a higher SG number, so as it warms it would reduce in SG.

 

[Ziggy17]

There aren't very many ways for salinity to increase. Basically, either evaporation, unintended dosing, topping off with saltwater, or measurement error.

Given that one of your fish died, it's possible that there really was a rapid increase in salinity.

I'm not trying to be rude here, but the sequence of events isn't completely clear, so I'm going to rephrase it in my own words and please let me know if I have it right.

On Saturday, you cleaned the sand. Why did you clean the sand, and how did you do it?

After cleaning the sand, you performed a 50% water change.

At 6 PM, you checked the salinity and it measured as 35 (I assume you're using Parts Per Thousand and not Relative Specific Gravity).

After the water change, you noticed that one of your fish was distressed, and you did a 10% water change.

When you checked in the morning, one of your fish (the same one that was distressed?) was dead, and salinity measured 40 at that point.

Here I'm not entirely clear. You say you added 10% new water plus mixed in some osmosis water. Did you add extra salt water, or did you change 10% of the water and then mix in some osmosis to your tank to correct the salinity to 35?

After an hour, your salinity was once again at 40. In this same time frame, your pH dropped from 8.0 to 7.5.

How quickly did you mix up the saltwater? What's your procedure for making sure it's correct?

I think @Seven Year Nap might be on to something. Assuming everything you've said is accurate and you didn't have a measurement error, the only way for salinity to increase would be for something to dissolve in your water. Could be undissolved salt, could be precipitate in the tank dissolving in the lower pH.

Even undisolved salt won’t change it that much, especially after 5 hours of mixing.

It’s a measurement error or the OP is leaving something out of the post. Nothing about it makes sense.