They are good enough to run a quick simple test but the readings do have a large range & will not give you a reading to the 10th decimal point. I have 5 tanks running, 2 reefs & 3 fowlr & it would take hours to test every parameter on all the tanks, so I use the API strips to get a ballpark reading on NO3 & PH only, any of those two readings are high or off balance, then I know there might be some issues with the water chemistry. If I get any unwanted reading on the strip, then I pull out the master kit & run a thorough test on all parameter, which I do religiously every Sunday. I’ve never used the aquavital brand, I didn’t even know they were around. As always, the best line of defense is you developing keen observation skills & proper fish husbandry skills, that’s a must in this hobby. You will be surprised at what can happen in the course of a 24 hour period, believe me. The animals will always be your first indicator to something wrong within the water chemistry. The strips are not an accurate tool that can replace a proper parameter test kit but more like a placeholder or support to your master kit.