First, I'd like to acknowledge and reiterate some of the things that Jason said because if you indeed have nitrogen trichloride in your pool, then aeration of the water combined with lots of ventilation will remove it. Also as he points out, sunlight will break down nitrogen trichloride so exposing the pool to sunlight (UV light, actually) will also remove this irritant.
OK, now for the bucket test. Basically according to the best breakpoint chlorination model I have, nitrogen trichloride will not get broken down by additional chlorine alone, no matter how much you add. Ironically, it requires dichloramine or monochloramine to break it down -- that is, it requires the more basic forms of Combined Chlorine (CC). So for the bucket test, we're going to take pool water and add some CYA to it and some ammonia (and chlorine unless it's already there which I believe it will be). The reason for the CYA is to slow down how fast the chlorine will react because when chlorine is reacting quickly, it tends to produce more of the bad nitrogen trichloride while when it reacts more slowly it tends to allow the intermediate monochloramine and dichloramine to form thereby minimizing the amount of nitrogen trichloride that is formed. If all of that was over your head, don't worry about it.
NOTE: You should read the following instructions first to see everything you will need and to make sure you understand it all. I didn't write this in the form of a recipe.
So, first take two large buckets of roughly equal size and shape and fill both with pool water leaving some room at the top so you can stir without spilling. You need to either know or measure the volume of these buckets (actually, of the water in them, so draw a line at a known volume level). You will also need an additional bucket for diluting chemical additions, but it doesn't have to be the same size or shape as the others, but does need to have a known or measured volume. The dilution bucket should ideally be dark, even black, so that you can see any undissolved chemicals at the bottom more readily.
Get some Cyanuric Acid (CYA) either from a pool store or from a friend with a pool who has some -- you will only need a very small amount. Take 2 teaspoons of the CYA (which are usually small round pellets) per gallon of volume in the dilution bucket and grind them using a mortar and pestle or whatever other creative method you have for crushing them into a finer powder. Then, fill your dilution bucket with tap water and add the crushed CYA powder into it and stir until it is thoroughly mixed, which might take some time. If you see any residue at the bottom of the bucket, keep mixing. Now take one fluid ounce (which is 2 tablespoons or 6 teaspoons) per gallon of the CYA water from the dilution bucket and add it to one of the pool water buckets and then mix the water in BOTH buckets about the same way for the same amount of time. Use separate stirrers for each pool bucket (and probably for the dilution bucket as well).
Measure the FC and CC levels in each pool water bucket. I assume you will already have some chlorine in the water so just note how much that is. You'll want to increase the FC to 4 ppm so scale up the following dilution instruction which is for a 1 ppm FC increment (you only scale up the 2 teaspoon amount, not the one fluid ounce amount). To increase the FC by 1 ppm, you would add one fluid ounce (2 tablespoons or 6 teaspoons) of 6% bleach in the dilution bucket (emtpy it, rinse it out and fill with tap water first since it will still have CYA in it) and mix and then take 2 teaspoons of this mixed solution and add it to the pool water bucket where you added CYA and ammonia and then mix. Mix the other pool bucket in the same way and for as long.
Now, get some household ammonia and see if you can get some that has an ingredients label so you'll know the concentration of ammonia. Usually, household ammonia is 5-10% in strength though some are even less (3.5%). For the quantities I'm going to give you, I'll assume 10% strength so you can scale accordingly. Empty out and rinse out the dilution bucket with tap water and then fill it with tap water (to the known volume). Add one fluid ounce (2 tablespoons or 6 teaspoons) of ammonia and mix. Take 1/2 (that's 0.5) teaspoon of this mixed solution and add it to the same pool bucket where you added the CYA and mix. Mix the other pool bucket (that doesn't have CYA nor ammonia in it) in the same way and for as long.
Wait 2 hours and then remeasure the FC and CC levels in each pool water bucket.
Post your results. If all goes well, you should see the CC level much lower and hopefully getting close to zero. Then the trick will be to properly scale this up for your indoor pool.
The above essentially creates a mixture of 4 ppm FC with 20 ppm CYA and 0.5 ppm (as ppm N) ammonia where it is assumed that the 2 ppm CC is nitrogen trichloride (which is 0.4 ppm N). It turns out that the FC level isn't critical. What is important is having the ammonia amount be about the same (or a little higher) than the nitrogen trichloride amount measured in the same units. It's also important that the active chlorine level not be too high which is why I used CYA.
Richard