Salinity gone DOWN - why?

[InAtTheDeepEnd]

Dumb question alert! 

Trying to maintain salinity of 1.025 

Water change yesterday and the new water i added was 1.025. and the original tank water was also 1.025 

 

But I tested just now and it was 1.023 😱😱😱😱 this seems really, really low and I don't understand what's caused the decrease.

 

Corals still ok though the tank has been getting too hot in the day as well (27°c up from 25°c, which I need to prevent happening as well somehow.) 

 

Ideas please, both on why this has happened and how to rectify it/prevent it happening again? Answers preferably in words of one syllable for an idiot....👍

 

[PeterU]

Calibrate your refractometer. Make sure you wait for the temperature to balance.

[seabass]

There are some corals that would be sensitive to that kind of swing in specific gravity, but most would be alright with it.  Top off with a bit of saltwater to bring it back up.

 

Like PeterU mentioned, it could be a temperature compensation issue (although many of our refractometers automatically compensate for different temperatures).

 

Your tank's temperature is obviously affected by room temperature, your equipment (like pumps and lights), as well as evaporation (which can be affected by a number of factors).  27°C (80.6°F) is actually very good.  I wouldn't be concerned with that.

[InAtTheDeepEnd]

After calibration it's 1.024. 

 

I think 1.024 - 1.027 is an acceptable range for reefs isn't it? But I thought temp should be 23-25°c so mine is pushing it a bit. 

When it was 27°c the zoas retracted but at 26°c came back out. Do I actually need to worry if they seem happy even if it's outside recommended ranges?

[InAtTheDeepEnd]

Ok it's gone back up to 27°c but only the gsp is retracted now

[seabass]

26 minutes ago, InAtTheDeepEnd said:

I thought temp should be 23-25°c so mine is pushing it a bit.

I'd say it's closer to 76 to 83°F (24.4 to 28.3°C): http://www.reefkeeping.com/issues/2004-05/rhf/

 

Stability is often most important.

[InAtTheDeepEnd]

oooohhhhh I don't think I've been leaving it long enough to correct for temp. 

Got this just now after leaving it to sit for longer 🙂

 

[PeterU]

2 hours ago, seabass said:

it could be a temperature compensation issue (although many of our refractometers automatically compensate for different temperatures).

 

Someone will correct me if I'm wrong but the auto temp compensation is to adjust the readout to 20 degrees (or whatever your instrument says). You need to wait about 30 seconds or more for your test sample and refractometer to achieve the same temperature.

[InAtTheDeepEnd]

And I'm working on keeping the temp lower - it's because the room it's in gets direct sunlight from two directions and is at the top of the house so earlier today it was about 30°c in there 😱 which is too hot for my other animals anyway, never mind the tank. Window open and a fan going now. 

[InAtTheDeepEnd]

13 minutes ago, PeterU said:

Someone will correct me if I'm wrong but the auto temp compensation is to adjust the readout to 20 degrees (or whatever your instrument says). You need to wait about 30 seconds or more for your test sample and refractometer to achieve the same temperature.

See response above - it was an issue with auto temp compensation.

Or rather, the temperature compensation was fine, the user was too impatient 😝😂