Almost ready for Toothless to move in!

I'm mega excited, I'm almost ready for my axolotl Toothless to move into my tank. It's in the final throes of cycling (There's no readable ammonia left, the only thing remaining is nitrite and nitrate) and I've just thought of a few things I'd like to clear up before I bring him (or possibly her, Toothless is only a baby) home.

First up, plants. Anyone have any recommendations? I have a moss ball right now, and a few free-floating plants I got from a previous teacher who had them in his axolotl tank. At the moment I have a clean-bottom tank, but I was thinking in perhaps getting some substrate on there. Could anyone recommend what works best for them? I'm just not sure what type of sand I should get, or if I should use soil with it.

Also, I'm looking in to possibly getting another filter, but I'm kinda low on funds at the moment, so a fairly inexpensive one would be best. This is basically the filter I have right now, except I think it's another brand. It was what came with the tank when I bought it. I also haven't changed the cartridge in that filter yet, since I've been waiting for it to cycle, but I've been keeping up with regular water changes.

My final question is something I really haven't seen much about anywhere, but there seems to be a pretty stable build up of algae on the walls and bottom of my tank. My only question is if this should be a concern of mine? Or is it best just left alone.

Again, thanks for everyone's help!!

I tried soil in my turtle tank and huge mess it worked by clogged up my filter in day's or hours because Raphael would dig around he loved it but it gave me a headache I use playground sand from Lowe's you have to wash it before using in the tank and I mean a lot of washing but it's cheap plentiful and iv had no issues past the first washing I was told by many fish keepers that's the sand they use iv bought sand from fish stores and it's the same lot of washing at first but lot more expensive and it's a bigger grain and I did read something about a axolotl being impacted by sand don't know what kind tho but playground sand is very fine grade so SHOULD be the easiest and safer way to go only way to be 100% is go bare bottom I just personally don't like a glass bottom those are for boats with Doris Day

The algae shouldn't harm your axie, it might look annoying though. You can scrape it off if you'd like. I've heard of so many axies being called toothless it isn't funny lol

@Shivermetim: Thanks! I'll have to look in to getting some. I'm fine with a bare-bottom tank, I'm just thinking ahead in case I ever want some plants that need substrate.

@TallTree01: I mean, I guess it makes sense, since Toothless is an adorable little dragon, and he kinda looks like an axolotl, but I picked it as Chris Sanders is like, my main artistic inspiration. My first axie was named Stitch. It was either Toothless or Ogo, but since I'm getting a wild type, toothless seemed more fitting. If I get an albino or leucistic that might be my little Ogo.

I highly reccomend rotala Indica as a plant for your tank. Bushes up, looks great and axolotls will hide in it. Mine is growing like wildfire, check it out

@Keyhubble: Thanks for the recommendation!