@MnFish1 I'm curious of your take here. why the discrepancy in readings, and which kit would we choose.
this color variation/readout challenge is unique because we're not in a display with undoubted compound surface area, this is a bare minimum setup subject to doubt. I'm passing it for basic ammonia control due to ratios of bioload used compared to surface area schemes/HOB filters are common and work well in the disease forum and she's got an alert badge that passes safety too. only the api says not safe above.
so even if we vote the tank has free ammonia, why would salifert give us a false low reading, along with the alert badge
what in your opinion makes api not agree with 2 other non digital test kits here
When I look at all (I think) of the API tests posted - I would have read them all at 0.25 - as compared to anything higher. When I look at the other 2 kits posted 1 clearly is 0, the other looks like 0.15-0.25.
There have been numerous studies, polls, etc about false positive ammonia rates using many of these tests - and overall - and there does not seem to be a difference during these studies between the 'big 3'. With regards to API, many people have not had false positive ammonia levels while almost everyone has 'heard' that API tests often give false ammonia readings. Suggesting that this more of a perception issue as compared to a widespread problem.
In my experience the API ammonia test is very 'difficult' with regards to needing to follow directions. I did hundreds of these tests and they always came out pure yellow 0 - using multiple kits. When a measured amount of ammonia was added they came out correct (i.e. using a syringe and a measured volume of Dr. Tim's ammonia).
Difficulties with API IMHO:
1. is the dropper in the test kits - they need to be held vertically in order to get proper results. Not just 'the same way' for each drop.
2. The timing needs to be followed exactly. if it says 'shake vigorously for x seconds - you need to do it.
3. If it says shake the bottle vigorously for x seconds - don't do it for x/2
4. If it says 'read at x minutes' read it at x minutes. not x+1 or x-1, etc.
5. The color charts (like the others) - can be difficult. You do the reading in bright (not incandescent) light I like to do itlaying as close to flat as possible - not standing up - which is how many people post their pictures here.
6. The reading (according to the instructions) - is that the 'level' is the closest color. I.e. if the color is more yellow than green - the reading is not 0-.25 - the level is 0. Squinting - for some reason seems to help with the reading of all of these color based card tests.
Now - I have also tested (not scientifically) - the other tests as well. I find the color changes even more difficult to read than API. If you look at the pictures of the cards posted - you can see that many of them are actually very close - and depending on lighting - I could easily read a couple different measurements.
I would say - based on pH - at no time were any of the levels anywhere near 'toxic' - and I'm glad the OP didn't 'panic'. (though I would obviously not have added fish when the level was 0.75-1.
Conclusion: I think all tests have reading errors - including Hannah. All tests have 'correct' readings - including API - I would tend to go with the studies that have been done and posted on various sites - and say - there is no reason to use one kit vs another as far as 'accuracy' - with the exception that some kits stop measuring at 2 ppm total ammonia, and API kits are not graduated to give as 'exact' a result as some others i.e. alkalinity - you can get 8 or 9. not 8.7. etc etc.
Lastly - I would suggest based on my use of Dr. Tim's - depending on how the drops are added to the tank - there can be significant differences in the actual ammonia added to the tank. I.e. instead of 2 ppm - you can actually end up with 5-6 ppm - which causes problems for certain bacterial strains.
and you going to have different opinions but 25% weekly water changes is quite a lot if your NO3 is low or have no corals.
