The Puffer Forum

I never thought to ask this before: which do you use on BW, fresh or salt? I have several tests that can go both ways but a couple that are for one or the other only.

For BW I use Freshwater liquid test kit

I use a salt water kit for my brackish tanks..

However, just wanted to say...

I have used my SW kit to test fresh water, then took water from the same tank into get tested by a pet store and the results were they same as my SW kit said.

Is there any real difference between the kits?

I asked the same question when I started with BW tanks. And I can't remember what answer I got. But the brand of water test I use, can be used for both FW and SW, so I can imagine the result being something in between.

purplecandle wrote:Is there any real difference between the kits?

In the test I use, the test is the same, but the color chart is a little different.

dang me too ... PP said all the tests are the same except for 2 and I forgot which 2...

Just buy one of each

If I remember correctly the previous answer to this question was FW kit for BW. API of course.

Every thing I've read says to use a FW kit. I've noticed that if you look at the boxes for the individual ammonia, nitrite, and nitrate kits it says "freshwater/saltwater" right on the front.

I also notice that the ammonia on the API FW kit has a slight greenish tint to it when used for BW.

Well thanks for clearing up the confusion

A couple of my tests have separate color charts. Seems logical that lower end BW would test more accurately with a FW kit, but then again sometimes my own particular brand of logic fails me

The kits may or may not be the same, but the reading scales are not the same. There is an effect called "water of hydration" which influences colorimetric tests in solutions with multiple dissolved salts. It can distort the readings as the higher ionic strength somewhat masks certain indicators colors.

It may be Greek, but it is real. Some tests are not affected, others are not.

At very low specific gravities - such as 1.003 for F-8s - the FW kits should be okay. At and above 1.005-8, I'd follow the kit maker's guidelines or suggestions. At low ionic strengths, there is not much detectable effect. Anywhere from 1.005 and up, it depends on the particular kit.

HTH

Thanks, RTR. I appreciate the explanation and it makes sense. I'm keeping that tank at 1.004, so I'll stick with the FW test kits or color charts.