This is becoming an ongoing drama now.After 4 weeks The nitrite levels are just not coming down at all. I have starved the fish for a week I have put filter start in after changing the filter and doing 20% water changes every other day and still nothing. I have been advised at the shop to carry on changing the water every other day until Sunday then they are talking about selling me some more chemicals. After buying my filter, a Marina i25 from them they are now telling me that they don't like using them filters. Ffs why did they sell it to me then?. Should it really be this difficult guys it is becoming a nightmare now.