Refractometer

What is marine conditioner ? Do you mean tap water dechlorinator or is there actually some product called "marine conditioner" ?

Salinity is a bit high. When did you last calibrate your refractometer and how? Temperature might be a little high too. But it seems there is something in your water or salt since you say you did a water change and everything reacted negatively instantly. I'd say that's your culprit and carbon alone will likely not do the trick.

By Marine Conditioner do you mean this?

Do you use this often?

Well it's probably because you're using tap water and not checking the new saltwater salinty.

You say you're not sure if you added too much salt...... Why wouldn't you check the salinity before doing the water change?

anytime you say this in reefing, bad **** happens. There really is no room for "oops".

Oh! Interesting. I didn't realize that there was such a product. Sounds like it's a dechlorinator with a bunch of other magic in it.

For your tank's salinity to jump 4 points like that, it means your change-water salinity was WAAAAY HIGH, probably in the high 30s. That would do it for sure. Especially if at that high a salinity the water temp was off and the salt was not fully mixed.

For instance, if you did a 33% of total water volume change and your tank salinity jumped 4 points, then you were 12 points too high or 1.037 in the bucket.

If it was a 20% water change, then your bucket was at 5 times four points too high or 20 points (i.e. 1.045 salinity).

Pouring in a large volume of super saturated high salinity water will definitely lead to some of the issues you've listed.

Anthony

You have been pretty vauge about your water you use and the details of your system. Sounds to me like the water you added wasnt good. Do you use tap water or ro? Salinity is deff to high as well, that would do it.

perhaps something else is present, i.e. soap on your hands, grease, copper???