Elos exclusively that they are also Lab grade
Nope, not a lab but hobby grade but a hobby grade done more to lab grade stds.
Results ?
You will never get any of them reading the same usually as kits are not exact there is always error factors and accuracy factors, like +/- 10 % of reading or Vol. errors. Some Alk kits for example do not titrate to seawater Alk but FW. Why, they just don't know this is needed. So, you can loose a small amount of the Alk, meaning it is actually slightly higher like maybe 5- 10 %. Same issue on pH test kits. Almost all pH test kit use a indicator, par the SeaTest, that has a "salt effect error", meaning the chloride in the water skews the kit reading. For example in LaMotte's high pH test kit they will tell you that if you are using it for seawater, to subtract 0.50 pH form the reading, 8.3 reading - 0.50 = real pH of 7.8.
One of my buddies has tested most hobby kits and the Elos and API seem to be right on. I also had Jesse, from Elos, sent all his kits to a certified seawater lab for verification. They did very well on the tests.
You all most remember that most kits, be they hobby grade or Lab grade are for the most part FW oriented. This is something Salifert has tried to do, set their kits to seawater stds. For some kits it makes no difference if the water is FW or SW. And the 2 most commonly errored are pH and Alk.
It needs to go high enough for SW. It has to go to 1000's of ppm. Usually, 1000 ppm Calcium Hardness = 400 ppm Ca++ and 4,700 ppm Magnesium Hardness = 1300 ppm Mg++, so 1000 + 4700 = 5700 ppm Hardness. So, the kit has to go to at least 6,000 ppm Hardness.
