I just do 100% water changes every day or two when I am feeding brine shrimp. The brine shrimp die so fast in fresh water that the water quality declines to a life threatening point pretty quick. Once the larvae are eating bigger things that don't cause the water quality issues I don't need to change the water so frequently. I just pour the newt larvae container into a net over another container. I use a net with holes that allow the dead brine shrimp and other debris to fall through the mesh but that retains the larvae, this is just the standard size aquarium net mesh (not one of the fine mesh nets). A quick wipe of the original container, refill with aged water and then invert the net into the clean container. I have raised hundreds of ribbed newt larvae this way.
