+1

based on what I have found in aquarium stores over the years I use anacharis, vals, small potted (crypts), plus amazon swords. On 10-20g tank I use 4-8 bunches of anacharis, 4-8 vals, 4-6 potted, and a single amazon sword. You could upsize to the 120 but would probably not need to do a direct porportional upsize.

For a substrate I use 1" peat moss ($10/bale), 1" play sand ($3/50 pound bag), 1" pro choice select ($8 50 pounds bag). For a 120 I would google pro choice select and contact the factory for a local source. You could also use aquarium gravel but that would be more expensive.

I add a layer, fill with water, clean the tank and level the layer then add the next.

After all three layers have been added I plant the plants. Then fill the tank with water poured over a dish.

I let the set 1 week then add a single male platy. Then wait a week with no food being added. I then add a female or two. in 6 months you have a tank full of platys.

For a larger tank you could add more smaller or a larger fish initially.

For lighting your should fine. If the 120 is 4' long, home depot shop lights with 6500k tubes would be good. The fixture is $9 and the tubes are 2 for $6. 3 fixtures would be 6 32 watt t-8 tubes for 186 watts.

With that you should be good to go.

Oh yea. I use no filters, no circulation, straight untreated tap water, and no water changes. Sometimes I get cloudy water and I just kill the lights and stop feeding for a few days until it clears. the resume with less feeding and shorter duration lighting.

I have tanks run for up to 8 years with descendants for the original cycle fish.

my .02

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fw leiden since 1979, fo salt since 1979, mixed reef 55g 2002-2009. Strong emphasis on the tank taking care of itself. Balanced with plant life, no water changes, tap water, no filters in FW. Only dosing calcium, alk, mag in marine reef tanks. http://www.aquariumforum.com/f15/my-...ods-26410.html
recent tanks (till 2009) 7 years- 10g FW leiden 7 yrs, 55g mixed reef 7, 2 yrs, 20g FW leiden, 10 g fw leiden , 29g mixed reef, current tank 55g leiden