[Lupin]

i do water changes every 3 weeks. i went to my lfs and they said that the parameers were fine

I'll have to repeat Dawn's call.
Point is, without those numbers, there isn't much anyone can tell you.
Your lfs deserves a slap from me.:shake: You need to jot down the exact figures. I would advise getting your own test kit instead so you'll be able to know your water parameters without the lfs intervening by claiming 'it's fine/perfect', etc. API Freshwater Master test kit is one of the good test kits out there. Easy to use and accurate. Avoid test strips which are not accurate enough.