No DO NOT do that. That filter is more than just a filter. It is a Deionizer. It stripes the water of any and all mineral content...well strips it down to 99.999% pure H2O. putting it in your tank then adding the buffer chemical and electrolytes will mess with your PH causing drastic sudden spikes. No cool for the fishies. Mis it outside of the tank. Yes it must be added! The PH adjuster needs to be put in because without it your PH should be around 5.0 after going through that filter. The electroright because the fish have got to have some trace minerals and electrolytes in the water.