New Setup of Planted Goldfish tank

this is my first thread.... feel free to comment yo...

after almost 2 years having a 5ft planted tank with hundreds of small fish, pleco, shrimp. recently buy 3 Gf and put in inside. next 2 days 1 Gf die. the other 2 left look so weak just dun wan to swim. just release that my Gf cannot fight with my guppy when eating food. Gf always run away as for the guppy that snap everything.

so decided to make my own Planted Goldfish tank

D-6... googling for more info....
1. many thread here says cannot put Gf with plant... they will eat all the plant. but still tank without plant to me is dead tank (even though with fish ). what plant is better ?

2. create tank with plant means that we need to put sand below. heard that Gf also might eat the sand and choke => afraid it will be die. should I use medium gravel instead of sand ?

3. Plant = need CO2 unless moss type. but Gf need many O2. is it OK for Gf ?

4. I am planning to use ext canister (more tidy and easy maintenance). read also that canister no good for Gf coz it stockpile nitrat and amonia inside. to solve it also to add more O2 inside like air bubble and place the inflow water higher than water level. is it correct ?

5. after reading bro blackgf thread : <sorry cannot paste the link>
waks... so difficult to have a Gf tank... so many disease... and need coral reel gravel to filter the water... is it really necesssary or only when ur gf got disease then u do that ?

please guide me all the Gf shifu and bros...

tonight start to hunting all the equipment.... wish me luck guys

cheers....