Out of tap im testing .5 ppm ammonia… im dripping as much as 200% per week and not registering any ammonia in tank. Im aware its in there somewhere but are my filters breaking it down at all since theres no evidence on a test?
If i really push the limits with the tap water drip i can get my nitrates to go up instead of down but i keep them at 5-20ppm at most. Im not opposed to using safe/prime with a chemical injector but what am i treating/removing if its not enough to register in tank?
This is going to get a bit technical but bare with me.
First, ppm is a unit of measure; specifically it is used to represent a concentration of something (typically a soluble chemical) within a solution usually at the rate of
1 milligram per kilogram (mg/kg) or 1 milligram per liter (mg/L) (this is specifically when working with water-based solutions). This is important since you're trying to find out if the .5 ppm ammonia you are reading from your tap is actually being processed. We know the nitrogen cycle is ammonia -> nitrite (NO2-) -> nitrate (NO3-).
Notice that ammonia was not given a scientific notation as this is going to depend on the type of tests you have available to you. Assuming you are using a standard liquid test, like API Master Freshwater Test Kit, you're probably testing for total ions which tests for Total Ammonia Nitrogen (TAN) which is ionized ammonia (NH3) and unionized ammonia (NH4+) aka ammonium while considering all atomic weights. If you have access to a spectrophotometer or to a lab you will definitely be testing for TAN but typically the test results are inline within the Nitrate-Nitrogen format (NH3-N for TAN or NH3-N and NH4+-N for ammonia and ammonium respectively) which tests only for the Nitrogen and ignores the other elements. This is important as you get two different numbers as an end result.
To demonstrate this we need to get the molar mass for nitrogen and oxygen (look at a periodic table/use google):
N = 14.01 g/mol
H = 1.008 g/mol
O = 16.00 g/mol
which means with an API Master Freshwater Test Kit you will get NH3 = (14.01) + (1.008 × 3) = 14.01 + 3.024 = 17.034 g/mol
but with spectrophotometers you will typically read NH3-N = 14.01 g/mol since you only consider the nitrogen.
In both case NO3- = (14.01) + (16 × 3) = 14.01 + 48 = 62.01 g/mol
Finally, since this process is simply a conversion of nitrogen into different forms we can get the conversion factor through division:
NO3-/NH3 = 62.01/17.034 = 3.64036632617 ~ 3.64
NO3-/NH3-N = 62.01/14.01 = 4.426124197 ~ 4.43
Now we can just multiple this factor to the ammonia to get how much nitrates we should expect to see:
Total Ion testing: 0.5 * 3.64 = 1.82 ppm
Only Nitrogen testing: 0.5 * 4.43 = 2.215 ~ 2.22 ppm
Of course while mathematically accurate this is assuming a few things:
1) No new nitrogen is added into the system
2) None of the nitrogen is used while the conversion is occuring
This of course is extremely difficult to test in a living, breathing aquarium as fish naturally release trace amount of ammonia, various microorganisms + to an extent your fish will use the nitrate in the water as a nitrogen source, and fish food will have a variance in it's nitrogen/protein content. Still, you should see at the absolute minimum an increase between the ranges of 1.82-2.22 +- probably ~0.5 ppm of nirates.
tl;dr you should expect to see roughly about ~1.82-2.22 ppm of nitrates from .5 ppm of ammonia. Calculating the rate at which you will see this increase is an entirely separate post.
edit: Forgot to answer a key portion of you post. You are likely treating chloramine (NH2Cl) if you are reading ammonia after treating your tap water. This is because chloramine is simply free chlorine (hypochlorous acid HOCl) bound to ammonia to stabilize it in water.
HTH
www.qcsupply.com
… didn’t even know this was an option.
… been pretty religious about testing my tap and my tanks for days/weeks now. Initially i cut my drips in half to see what would happen. “Homeostasis” pretty much stayed the same… so i went to 3/4 drip on some tanks and 100% of my “normal” drips on others which are over 150% fresh water a week and i cant see a difference in anything other than my tap still registers a bit of ammonia on tests as well as my “new” filtered water. My tanks all read zero ammonia which is a big positive. Nitrates range from 5-20ppm pretty much as they always have for the last 12 years dripping. 
. Like ur thinking also, is the tiny amt. of chloramine “lost in the ocean”?… id like to know for sure 
