Looks like you're off to a great start! I f'ing love the Oase filters. The removable rod thing for cleaning the prefilter sponges is a game-changer. I started with Eheims, but I don't think I'll go back.
I think in regards to your question, you don't have to use power sand. It will help you keep things set up and thrive for longer by providing extended nutrients for, I want to say it's something like 6-8 months? Eventually you'll want root tabs of some kind (I've used Seachem and NilocG with success). So the other option is just to start of with root tabs right away and just use aquasoil. I've definitely had power sand (btw I hate it's called sand when it's literally rocks) pull up when rescaping and it can cause some algae blooms and such if left open to the water column. So yeah, keep in mind what your plans are. Being new, you may feel the itch to change things up frequently, so if that's the case, I might suggest the root tabs instead so you don't pull up bits of the power sand. If you think you'll leave everything for a long time and have the $$, go for the power sand.
For your plants, I might have cautioned you against UG. It's difficult to grow for many. If you get things right, you'll be set and it can look great. Other options for the classic iwagumi look that are similar might be dwarf hairgrass (sp belem is a classic, but there's others that have come up in my absence). There's always microanthemum monte carlo which is really great to grow, a little bigger that hemianthus callitrichoides (HC cuba) and easier to grow. If you want another grass looking, medium plant I'd suggest blyxa japonica, looks great IMO. Other smaller, leafy plants include staurogyn repens, bucephalandra, and anubias petite sp. For a pop of color, you can't beet any of the plethora of ludwigia or rotala sp (require lots of trimming with good light/nutrients/CO2) or alternanthera reinekii mini. Other more exotics include hygrophila araguaia or pinatafida (may not be the leaf shape you're looking for). Hope that's helpful. With your setup you should be able to grow most anything (though that will depend on water quality as well if you're using tap vs RO remineralized).
Also, wash those rocks, haha. They are filled with clay like dirt in all those holes so take a hose or sprayer to those bad boys and don't stop until it comes out almost perfectly clear. I also recommend a bamboo skewer or other stick to dig into the holes and break up the dirt chunks. Otherwise you'll have muddy soil, glass, plants, and filter once you get everything filled.
Anyway, keep up the good planning and yeah, try to not move too fast! Planted tanks require time just like the saltwater you're used to, so don't make big changes too quickly. Looking forward to seeing your progress.
I wanted to say thank you for taking the time to look at my journey thus far and giving me some great advice.
Starting with the rocks, I decided to go with seiryu stone instead of the dragon rock. I'm going to hold on to the dragon stone for maybe a future or second project down the road. I'm in the process of hunting down the right stones for the look I'm going for. (More to come for sure with pictures)
I knew that water was a process all of its own, and I am still in the works of trying to figure out my long game with how I plan to keep parameters around my goal. With that being said, I did go ahead and purchase an RODI system. I went with the AQUATICLIFE twist in 100GPD system. https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Still waiting for it to come in from amazon! I also took your advice and plan to move in a different direction with plant choices. UG research has sort of frightened me. Do you have any advice on how you do your RODI and where I should store the purified water once its processed? I can't quite figure out where I'm going to store the water or how I'm going to do it just yet. I found a couple of ideas with storage, but I had no idea storage barrels could cost so much.
I purchased a TDI meter, and my local tap is very hard 300 ppm+. I did calibrate to consider temp and tested different times to make sure. Feels like I'm going through a never ending check list but I'm sure it'll all be worth it in the end.
Also, thanks for giving me feedback on the power sand. I did have some come in the mail, but like you have mentioned, seems like I may benefit from the root tabs that you mentioned so I'll also be swapping to those
You seem to be a fabulous resource for this project, and I thank you again
Look forward to hearing from you soon!