Salinity Problem ***

[marineang]

So I think my refractometer might need to be recalibrated. It's again saying 1.030. Hydrometer is saying 1.023 however I know they aren't reliable, I just have it for backup. Going to take it down to my LFS tomorrow and see what their water is testing at - or if they can recalibrate. The salinity on my small tanks showing ok. Here's my question - looking for a rough idea....
75g tank - how much water approx. would I need to take out to bring it up to a better level? I have the tank stocked so I want to do it slowly, I just need a vague idea of how much?
Thanks so much!

 

[masterhobbyist]

You should be able to calibrate your refractometer yourself. If you put some plain RO water on it, there should be a little

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on top. Turn the

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to O with plain Ro and it should be right on.

 

[apollobeachfl]

I have just set up a 90 gallon tank with no live stock as of yet. My Sal was reading 1.024 and I like to have it at 1.021. I removed approx. 12 gallons from the tank and added 12 gallons of RODI water and it came out to be 1.021. If you have a 75 you could remove about 2 gallons a day for several days without affecting the fish until you got it down.
I agree with Master. You should be able to adjust the refract yourself if you have access to RO water. If you put a couple of drops on it, it should read zero. If not there is a small

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just behind the lens that can be turned to adjust it donw to zero. You will need an eye glasses screwdriver in order to turn the

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.
I have never trusted Hydrometer or LFS to get the right settings. I bought some fish from an LFS and they told me their water was 1.024. When I got home and tested it with my refract it was 1.030 way to high so the acclimation process took much longer than I expected.

 

[marineang]

Thanks guys,
I actually think I'm in denial, I put RO/DI water on it and it read zero. I'm just frustrated that the salinity is so high and know that sometimes they need recalibration.
Yes...I hate hydrometers too. Seriously, if they are that far off, why do they even sell them??

 

[sean48183]

I have used the instant ocean one for 5 years and have no problems. As long as you clean it with fresh water after each use it should be ok. I also keep my water at 1.023 to give it a little plus or minus in either direction.