Using Aquarium Salt in Freshwater - Testing Salinity

[bjbass]

I read that you can use a Hydrometer or a Refractometer to test salinity levels. I have been treating my 210 freshwater tank with API Aquarium Salt as my smallmouth bass has a little fin rot. I have been doing the one tablespoon per 5 gallons and when I do water changes I figure on about how much water I take out to replace the salt. However, I want to make sure that it isn't too salty or not salty enough to treat my fish.

How do I test this?

My ph dropped from 6.6 to 6, so I think that I may have too much salt in there and it brought it down.

 

[jpappy789]

You're confusing terms.

Refractometers and hydrometers measure specific gravity, which has to do with the density of a liquid.

Salinity is a measure of the "saltiness" of water. However, take into account that aquarium salt is basically NaCl and there's more to salinity than just sodium chloride. There are several other salts that are measured.

There probably is a way to compare density of the aquarium to say the density of your tap using SG to figure out exactly how much NaCl is in the water but at the same time there probably will be other complicating factors. Not to mention I dont see how it would be any better of a measurement than what you are already doing...

At this point I think the easiest way would be to simply look at how much salt you are taking out per water change and add that back. That should not steer you wrong.

Also, aqueous NaCl will not alter pH in theory. Without knowing more about your water and how/when you tested it is impossible to say what caused the drop.