If you can't remove fish then perhaps a product that speeds cycle along and a product that detoxifies ammonia and nitrite as mr x said water changes effects the cycle as you need ammonia to build the bacteria you want, you are finished when ammonia and nitrITE isn't detectable and only nitrATE is.
175Ltr Aqua Marine 900, Marisys 240 Wet/Dry,
24W UV, 17.5KG Fiji Live Rock, Temp - 25C,
SG - 1.023, Amm - Nil, NitrI - Nil, NitrA - Nil,
Ph - 8.4, Alk - 4.3 Meq, Cal - 450, Mag - 1340