Help lowering salinity in tank

[drknudsenx2]

I just measured my salinity in 75g with 20 gallon sump (1/2-3/4 filled) and it is 1.031. I’m not sure how that happened. I have been topping off with rodi I make, and i just checked on refractometer at 1.000. Fish, coral, inverts all happy- does anyone have a suggestion on lowering salinity? Is there X amount of salt water to remove to replace with pure RODI?
Thank you!

 

[drknudsenx2]

And I checked my salt water bucket and it is 1.025. So I don’t know what I have done wrong during water changes to have it spike up.

 

[DivingTheWorld]

Did you calibrate your refractometer and with what? First, don’t do anything fast. Nothing living in our tanks like fast changes. Verify your salinity with other devices. If they all match, make small changes. Scoop out half a gallon of tank water and let your ATO refill with RODI. Wait a day, test again. Repeat.

 

[DivingTheWorld]

And I checked my salt water bucket and it is 1.025. So I don’t know what I have done wrong during water changes to have it spike up.

Are you dosing anything? If not, I sense a testing error somewhere.

 

[drknudsenx2]

I am dosing reef fusion to increase my alkalinity. It keeps decreasing to 6, trying to maintain at 8-9. The refractometer on pure water is 0, and on my home made salt water is 1.025, but ok tank is 1.031. So I’m not sure how that happened. I don’t know how else to measure/calibrate refractometer

 

[Mjl714]

I agree with previous comment and if you’re convinced 1.031 is accurate I’d remove a cup 8oz of saltwater and let ATO replace. Test salinity in an hour or two so that you can start to understand how must freshwater will eventually need to be swapped in. Then I’d spread that amount out over the next day or two. Slow and steady.

 

[drknudsenx2]

Thanks for the input. I will
Work on correcting today

 

[Spare time]

I am dosing reef fusion to increase my alkalinity. It keeps decreasing to 6, trying to maintain at 8-9. The refractometer on pure water is 0, and on my home made salt water is 1.025, but ok tank is 1.031. So I’m not sure how that happened. I don’t know how else to measure/calibrate refractometer

You need to use calibration fluid.