The tank looks great. I hate to sound really redundant if you have heard these little explanation and warnings (which I bet you have) but just in case you havent:
(1) The use of any substance that reduces ammonia, like your nitra zorb bag, should be used sparingly, especially while setting up a tank... cycling a tank is a natural process where you culture bacteria which breaks down ammonia (usually produced by fish waste, uneaten food, or dead matter decaying). In the ending phases of a cycling you will get a "spike" (a very high concentration) of ammonia, but the levels will eventually even out. If you use an ammonia reducer during the cycling process you will end up reducing the amount of beneficial bacteria in the end of the cycling process and the tank will need to slowly build its bacterial base.
(2) Live plants are rather hard to keep (and about as expensive as most fish). To get the results that you see in those amazing pictures that look like tiny underwater forests you usually need good high lights (for a tank of 20 gallons (US) its anywhere from $80-180, or for a 40 to 55 gallon tank its around $120-250; you also need a co2 system which costs anywhere from $30-500+; fertilizers are regularly needed ($5-15 a bottle); and if you dont get an expensive co2 system you will probably need something that monitors pH (at least a bundle of test kits)... some of the costs dont seem that bad but it builds up (I just started a new-used 20 gallon and spent at least $250 to get quality equipment, but then again you could definitely find some of this stuff for alot less). I am not trying to completely turn you off of live plants, I just would like to urge you to see how well the plants you already have fare in your tank over a span of time before you put down more money on plants (and dont worry, some people have alot of success with plants without all that expensive equipment).
(3) Your choices in fish are nice, here a little info about some of them if you dont know yet: The pygmy puffer may be a problem, a few weeks after you buy it, you will start noticing little portions of your other fishes' tails are missing and later you might start missing fish altogether (I had a pair of Figure 8 puffers, they would scratch the glass with their teeth and killed any fish that we attempted to quarintine in their tank (they were in a 20g and the other tanks were a 135g, 100g, and a 40g)). They also like brackish conditions (somewhere inbetween fresh and salt water). The tetras, danios, otocinclus, and glass cats are all schoolers, and you will need to keep quite a few together (good to have at the least 5 of a type). Ive heard that male bettas can be a little aggressive, especially with their own kind (they dont call em siamese fighting fish for nothin). Gouramis and plecos can be very touchy when it comes to water conditions (and plecos put out alot of waste), plecos also need a varied diet to do well (like algea wafers, vegetables, and driftwood (I dont know if this is needed, but they love it)- which you already have. Shimp are really cool to watch, but they have a habit of hidding really well. You should only get one sex (usually male is the only sold) of fancy guppy, because they will do it like rabbits and ruin your tanks delicate balance.
Wow, thats alot of stuff. I dont mean to sound overly critical or anything... and if I do, Im sorry. But your tank already looks great, and it looks like you will have lots of enjoyment watching all your fish.
