What murkiness are u referring to ?
I usually do a change every 2 weeks about 25%

For algae I also have a uv light so keeps the floating algae murkiness away

currently im using some pellets apparently specialized for koi which are packaged and sold by one of the koi shops near my home. looking to change this

would like to know, what other koi food you guys use here and use it successfully?

heard of Kenkokanri Hi Silk and Hikari gold but not sure what the price for these are and more importantly, are they that good?