Test results vary between meter and drop test - not sure what to do?

[waterbear]

I just bought a salt test kit today and tried it out. I had been thinking the aqualogic was reading high because when it was showing 3200 early in the year, I took the water to the store and they read 2900. Around the same time, I tried a salt strip and it showed around 2900, so I assumed the aqualogic was high.

Today, I took a sample to the store when I bought the Taylor salt drop test. They read 2900 with their probe. The aqualogic is reading 2800. I just tried the drop kit for the first time and it took 16 drops. Ugh! Just the opposite of what I expected. I'll try the drop test again this weekend and a test strip also. Maybe I'll take the water in to another store too. I'm not sure what to believe at this point. I guess I'll trust the aqualogic for a while and do some more testing.

For my test, getting to drops 13-15, the drops would go in, turn the entry point red, and the solution would go back to all yellow. It was the 16th drop that all of a sudden turned the entire solution red (light brown) and it stayed that way.

Robert

So that means you are reading 3200 ppm. That is not very far off from your aqualogic...It could be due to temperature difference since the aqualogic measures conductivity to determine salt level (and so do some meters) and temp can cause the reading to be low or high. I see about a 100 ppm difference in my pool and a 300 ppm difference in my spa with the readout on my aqualogic vs. Taylor salt test (still waiting on resolution on Ben's test) , Aquacheck White salt strips (which are ususally within about 100 ppm or less of the chemical test because of precision limitations of the strips) and the goldline meter we use at work (usually spot on with the Taylor test and very close to the strips.) I don't lose any sleep over it.

Remember that the precision of the Taylor test is 200 ppm. It means that there is a plus or minus variance of 200 ppm over the reading you get. Within that variance your test could be 3000 ppm or 3400 ppm. 2900 ppm tested with a meter and a salt strip and 3000 determined by a chemical test are close enough for government work!