12 gallon eclipse new aquarium help

[MarkA123]

Ok so I plan on getting a 12 gallon eclipse aquarium. My stocking plan is 3 Albino Cory catfish and 1 female betta I already own. Would this be overstocking? Iplan to use sand substrate with live plants. Would Marimo balls be good? I want marimo balls and some other live plants. I heard the eclipse doesn't have powerful lighting but can still support normal plants. What plants do you suggest? I don't test my water regularly but the guy at petco tested it and said it's fine for cories. I'm going to buy a 50 watt heater and use the pure ammonia cycle method. Is this a good plan? I'd like to hear you suggestions and opinions. Here's a YouTube video of what I wan it to look like.
YouTube - ‪Comrad the papa betta fish & his albino cory babies 12 gallon Eclipse aquarium‬‎

 

[SeverumGuy]

You'll be perfectly fine. You even have room for a bristlenose pleco in case the plants don't prevent algae from growing. They get up to 5"

 

[MarkA123]

Ok thanks would it be ok to add more female bettas or albino cories? Or would this make them hostile or be overstocking. I think I'm going to follow my 3 cories 1 Betta plan and in the future add more. Thanks for your advice!

You'll be perfectly fine. You even have room for a bristlenose pleco in case the plants don't prevent algae from growing. They get up to 5"