Does anyone use API master kit?

It depends on the lighting of the room you are in. I run to my fridge under the white light and its easy to tell the difference.

 

IMO, I think API kits get a bad rap.....I can only speak for the nitrate, calcium, and phosphate ones though. When I've compared my results on my API to my LFS and then to the salifert - API is pretty darn accurate.

 

+1
I've used API since I started, and I have my results tested against Salifert, and the only misread I've seen is my nitrates were reading 10ppm when the Salifert test said I was more like 3-5. IMO, if it's simply going to be a tad on the higher side, that's good enough for me. For daily testing I use my API, and if something just seems strange, or I just want a sanity check, I use my Salifert.

 

Using good fluorescent light is a giant help for reading the kits,but with the accuracy,theres alot of api vials that are mis-marked.

When I fill with 5ml exactly from a medical syringe,I get different water line readings.I know if I use precisely 5 ml from a syringe,the water will be over,under or sometimes right on the line.

I've found filling this way changed my test results and made the kits far more consistent and accurate comparing to my red sea pro kits.I've also found that 7 of my 10 api vials are not marked correctly.

 

if you really want to read easy use your comp screen meaning get a write screen up and hold it up to it i did this and scaned the cards into my computer but as stated before they are O.K., i just switched myself to red sea and salifert

 

I've used the master test kit. I sometimes use API for ammonia and that's about it during QT (and also nitrite for freshwater). Lately, I have been pretty much forgoing the API ammonia kit all together in favor of a simple seachem ammonia alert badge.
As far as the other tests.
1.) The Alkalinity is "accurate" just not precise from my experience (e.g.: if my alk is 8.7, API will read 9 just because it steps up and down in increments of 1). This is my biggest "complaint" with API.
2.) The nitrite works fine... but really in SW this test kit doesn't matter too much.
3.) The nitrate works... but again it is just not precise enough.
4.) The phosphate kit.... same issue as the rest.. not precise enough... I think it jumps from 0 to .25 ppm LOL. At .25 phosphate in SW you probably have major algae issues =).
5.) The calcium test kit.... Yet again just not precise enough IMO as it jumps up by 20 ppm per drop.
Again, the test kits are "accurate" just not precise enough.
I would just save the money and get good salifert test kits. Those have been very reliable over all for me and are a LOT more precise.

 

I use it for ph ammonia nitrate and nitrite I won't use the other kit ill spend the money and be confident in my results