Should never be a need to fishless cycle a tank if you already have an established tank from which you can borrow material already impregnated with the very bacteria that fishless cycling produces.(lot's of folk's do this,myself included).It's best to add a source of ammonia (other than fishes). Do a google search on "fishless cycling" and you'll find many articles explaining the process. If you want replies specifically from this forum, do a google search for "fishless cycling sitelantedtank.net" the top search results will all be from here.
Yes,adding some floating watersprite along with the seeded sponger filter would do the trick nicely.Would putting plants from established tanks help. Because I'm only housing bettas. I'm just going to be housing bettas by dividing a 5g tank into three sections.
All plant's are ammonia,nitrate hog's.(is food for them)A. Stick three sponges in your existing tanks for a few weeks, and then set up your divided 5g, plant it, and start adding bettas one at a time as the bacterial colonies grown to handle the bioload. In a few weeks, have a planted, cycled tank with fish.
B. Set up your divided 5g now, plant it with whatever you like (not having to limit your choices to nitrate hogs), and do a fishless cycle with ammonia or fish flakes and a couple of water changes. In a few weeks, have a planted, cycled tank and add your bettas all at the same time.
Same end result, pretty much the same effort and time frame. Which one you choose depends on your personality, the types of plants you want, and how fast you want to add bettas to the tank.
I'll be looking forward to pics of the tank once all is in place, fishkeeper01, and we can see what lovely bettas you choose.