I use elos for ca, alk and mg and find the kits to always be very consistent. I suppose I never know if they're accurate but i think water consistency trumps having your levels at precise spots anyways. these kits are very easy to use and my eyes have no issue at all detecting a colour change. kits that have you comparing colours stink i think but these have distinct endpoints.

I bough the phosphate checker and used it once. it read 0 which seemed unlikely to me and I haven't bothered to use it since.

You make a valid point... And no one has sold me on them LOL so I think ill stick to my Elso kits until they have made a better checker

I have elos, salifert and hanna alk and phosphate checker. I found that alk is a bit high, it is always 0.6 higher than both elos and salifert e.g. salifert will read 7.4 dkh but the hanna will read 8.0(with the conversion either time 0.056 or divide 0.056), hanna does have consistant reading if I might add. all I do is just minus 0.6dkh from the readings.

At one point in the test you have to add .1 ml of tank water. I find you need good eyes and a steady hand to pull this off. Neither of which I can boast of on a steady basis. But I'm slowly getting better too. PO4 and Alk are great. I hope they come out with a NO3 checker soon.

I love my hanna alk & phosphate checkers, accurate and easy to use, I don't like the calcium checker, pita.