The best replacement for algae is plants.

The best alternatives to algae are rated as following:
★★★★★  plants
★★★★  moss
★★★  mold
★★★  algae
★★★  seaweed
★★★  protozoa
★★  algal
★★  cyanobacteria
★★  fungi
★★  plankton
★★  kelp
★  spirulina
★  land plants
★  phytoplankton
★  pollen
★  chlorophyta
★  alga
  green algae
  mildew
  blue green algae
  chlorella
  fungus
  fish dha
  krill
  diatoms
  blue-green algae
  trees
  protist
  fish
  brown algae
  jatropha

Your alternative for algae is not listed? Suggest!
Speaking about algae, one probably shouldn't forget about high chlorine.

Other search terms related to algae and their ratings are:
★★★★★ high chlorine
★★★★★ dha
live rock
You have in mind a companion for algae and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of algae in all years. Click on graph for more.
algae
plants
moss