I'd say another fx6, but if that's going to strain your budget the 406 is definitely an improvement.Since I still have my old 406 can I use that or should o just get another fx6.
Is it better for me to get the Jebao PP-8 or should I just get Jebao PP-20 cause I'm gonna be upgrading my tank in the near futureKeep in mind the FX6 is a FAR bigger filter than the 406.
I agree with others, 2 FX6s would be good on that size tank. That will get you up to a reasonable 10X turnover.
If you're putting in a powerhead, maybe something like a Jebao RW-8. Fairly reliable, inexpensive, lots of wide slow current, but adjustable. Just point it towards the bottom of the tank and it should get everything circulating well and off the bottom.