Shakaho, Thank you for adding that, I have been using digital testers for so long now I really didn't remember the company that made that kit. for the money, ( Less than the cost of one nice Koi) that kits works great! I'm not a fan of test strips but even those are better than not knowing what the water is doing at all.
I laugh sometimes when people say that the ammonia level should read zero. With test kits like the one you showed and the test strips are designed not to show the low end spectrum of ammonia as not to confuse beginners that are starting to learn to use them, My meter reads ammonia all the time, EVEN Filtered tap water in our area contains .003-.006 ppm of ammonia. Most test kits start showing positive at .25-1ppm. 1 ppm is really already to a dangerous level as it is causing respiratory problems for the fish and is causing stress levels to elevate which makes diseases more prone. My digital unit reads .025-.050 in the pond and aquariums on most occasions. That reading is 100 times less than what a drop type kit will read and 1000 times less than what a test strip kit will read. But they cost 16 times more than those kits also. ( NOT CHEAP!) I lost a fish about two weeks ago in my 300 gallon pond. ( small 3" koi) It was alive when I checked it at 9am and the pond had a reading of .031 at 3pm when I found the fish I went and tested and it was already up to .079. I couldn't find any sign of decomp on the deceased fish but that short amount of time the reading had already climbed, some of that could be algae decomposing in the sun and waste from being fed earlier in the day but I want to say this so others can understand that ammonia is being produced in a pond 24 hrs a day all year long. yes even when the temp is right at freezing. it's just slowed way down due to the fish are then dormant and not producing body waste but there is still breakdown taking place for decomposition, and the bacteria are still feeding on that breakdown. Spring is when a lot of pond owners start noticing problems because the bacteria are trying to catch back up with the waste being produced and what has accumulated over the winter. Nitrates which are what is left over after the ammonia is broken down is now elevated and the best way to get those back down is water changes and lots of plant growth which uses the nitrates as a nutrient when they are growing. Dr. Dave taught me to read more on Dissolved Organics, I learned quite a bit in reading more about it. I tried installing a saltwater venturi protein skimmer on my pond, In less than two weeks I have noticed a great improvement in the foam that was on the surface, Lower ammonia readings, and clearer water. Using a good test kit showed me what I already knew but verified that the addition of removing proteins and DOC help in lowering the level that the aerobic bacteria were having to try and breakdown.