Using Saltwater Test Kit in Freshwater Tank?

[chotie]

hey all, first post! love the community btw.

i accidentally bought an AP saltwater master test kit online from bigals but i use a freshwater tank. is there a big difference btw the two? can i use it on my freshwater and get accurate readings or do i have to return/resell and rebuy the freshwater master test kit?

 

[TCTFish]

There is a difference between the chemistry between marine and freshwater. Because of this difference, test results from kits for the opposite may not be accurate and marine kits in particular may not be able to read the lower values of pH in a freshwater system. Best to get the right things for the right stuff.

 

[Purrbox]

In addition, even the test kits that can be used on both SW and FW usually have different charts for results. Since yours was sold as SW only it's very likely that it wouldn't have the FW charts. As such you won't know what the real results are. Go ahead and trade it in for what you actually need.

 

[Legacy]

I've done the research, here's the answer:

I have only brackish water aquariums so I was questioning how accurate my readings were. I have an AP SW Test kit and I was doing tests on very low-range brackish when I first started out. What I did was I went to the LFS and took a look at the refills they have for the test solutions. The solutions are exactly the same for fresh and saltwater but the difference is the charts, but by very little.

0 NH3 will show up a little more yellowish for freshwater, everything else was the same. When testing for Nitrate compare it to your saltwater testkit, take the reading, and multiply it by 2. That is your true freshwater nitrate reading.

Try contacting the manufacture and tell them you lost your chart cards for your freshwater kit and would like to see if they could provide you with new ones. Otherwise you could go to the LFS, look at the refill kits(because they contain both cards for fresh and salt), and compare and make notes. When you need to get refills for your solution you'll end up with both sets of cards and essentially a Master Test Kit.

If you don't believe me, look for yourself... do it just in case I'm in error. I've had no problems between any of my tanks ranging from SG of 1.000 - 1.016 using the saltwater testkit.

 

[chotie]

thanks for the info, all. i think i will just go buy a refill since i will eventually use it and get the new cards that way.