Things aren't as bad as you think. You don't need your nitrAtes down to 0; readings of 10-20 are just fine and what you want if you have plants. NitrItes and ammonia should be 0 but you may be misreading your chart. Post a picture of your ammonia reading (with the tube and the chart) so we can see. I've noticed before that the chart is sometimes printed more yellow-green and sometimes more yellow-orange for 0. My high pH water reads a cool yellow rather than a warm yellow at 0 (but it doesn't look greenish). As far as pH, yours is 8.2. The kits are set up to test either higher or lower pH up to 7.6 (which would be blue if that number or higher). Since yours shows blue on the lower test, you always test with the higher and use that number only--which is 8.2. I have three tanks, all planted and thriving, and all city tap water of ph 8.2--sometimes 8.4 during certain winter months (I have no idea why that is). The pH scale is logarithmic (look it up, you'll be surprised) and that means that unless you add massive amounts of RO or DI water, your pH won't change much. I used to use 50% DI water and my pH only reduced to 8.0, but my carbonates (total dissolved solids/hardness) did drop a great deal. Since the local aquarists said to leave it alone, I have and have not had any problems since switching to just treated tap water. My tanks contain lots of South American fishes, corys, etc. which are healthy, and all of my tanks contain living plants. Don't fight what you have to work with, unless you have unlimited reserves of RO water around. It isn't worth the hassle unless you are breeding soft water fishes or keeping highly sensitive ones like discus. As far as the brown algae/diatoms, it does take longer to clear up in very hard water like ours. A few snails will take care of the problem of that.
