Please help me choose right Flood light for 20 gal tall tank

Hello,

My first post. I have a 20 gallon tall tank it is approx. 24" wide x 12" deep x 16" tall and I'm looking to place 2 either 10 watt or 20 watt LED flood lights for a freshwater aquarium that I will be growing plants in using the Diana Walstad method so no chemicals, no Co2 etc... and looking to have Med-High lighting and may little high where moss at very bottom of tank can flourish as well. I plan on putting plants in my tank that is recommended in her book which I can't recall the names now with about 10 fish ranging from Sunset Gourami, 3 ghost fish, 1 pleco, 1 goldfish and about 5 others that I can remember the name now.

After substrate is added from bottom of tank to the ligh source it is about 13-14 inches.

My questions:

1.) Do I get a Cool White LED that is 6000k is this Kelvin good?

2.) Should I get one of the lights below from Amazon?

Quantity 1 - 10 watt 6000k - https://www.amazon.com/gp/product/B01GCIXJJM/ref=ox_sc_act_title_2?ie=UTF8&psc=1&smid=A2JBI4D2GZXI4O
OR
Quantity 2 - 20 watt 6000k - https://www.amazon.com/gp/product/B01GJOTI6C/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A1B33RI542K9SJ

3.) Looking to mount both lights under stock hood and so they will be about 2" maybe a little less from top of water surface is that ok? These shouldn't generate a ton of heat right?

I've been reading posts like this that shows what PAR readings are from certain distances from 10w & 20w lights, but it's a lot to take in lol http://www.plantedtank.net/forums/12-tank-journals/194214-28g-serenity-passion-2-acrylic-cube.html

Please help. I've been doing tons of reading on this site and ready to pull the trigger. I'm afraid if 20 watt is to much light and then I have an imbalance in what the tank ecosystem is producing vs. the amount of light and then having a Algae problem because of to much light causing more harm to the plants etc...Any help would be appreciate.

Thanks!