W/C's and drop in SG

[Aquattro]

I think most people here match SG BEFORE doing the change.

[Static]

There should be no change in specific gravity when you do a water change.

[bv_reefer]

i did test it before, it waz at 1.023 now it's at 1.021 if the hydrometer is right, but it was a bigger w/c at 20%

[SeaHorse_Fanatic]

I have found hydrometers to not be very accurate.

[bv_reefer]

:ya thats what i thought to, but i tryed 2 times with the same reading, 1.019!
i bumped it back up to ~1.021 for now

[Captainhemo]

Really give those hydrometeres a good couple of bumps and make sure it is sitting on a level countertoop when you read both when you are checking the tank and when checking you new water before adding it. Just holding the hydrometer at the slightest angle can "bind" the float/pointer and give you an incorrect reading.
As long as your nrew water is at or above the SG of the tank, there is NOWAY the SG can come out lower

[bv_reefer]

well i just put RO water, i didn't add salt because it was already at 1.023 so a 20% w/c with salt replacement would've kicked up to 1.025, i've never used saltwater as replacement water for a water change..