Its essential to achieve a natural ecological balance in your pond.  We can achieve this naturally with a few key steps.   Adding submerged plants play an important role in achieving success by removing excessive nutrients in the water and provide oxygen during the day for fish and other aquatic creatures.  The most important role is removing excessive nutrients that help reduce the incidence of algae which is the nightmare of most water gardeners.  They starve out the algae by utilizing all the mineral salts which the algae normally feeds from.

Submerged pond plants oxygenate the water during the day, but at night the process is reversed and carbon dioxide is produced.  This only becomes a problem if your night time temperatures are quite warm and you overstock your pond with fish.  Generally the more submerged plants you put in your pond the better the pond balance will be. 

Algae likes full sunlight so in addition to the submerged plants add floating plants, waterlily foliage or bog plants to cover at least one third to one half of your pond's surface, but no more than one half to be successful in controlling the green suspended algae.

There is a balance to achieve so make sure you don't cover too much of your ponds surface with plants or it will inhibit the submerged plants from growing. 

The recommendation is to have 1 bunch of submerged plants per every 2 to 3 square feet of surface area.  We sell submerged plants by the bunch so you receive 6-8 plants per bunch.   You can determine your surface area by multiplying your length by the width of your pond.  This gives you a general idea. 

A similar calculation is made to determine the quantity of floating plants and waterlilies for your pond.   Determine the square footage and remember you don't want more than half of the surface covered so that the submerged plants receive plenty of light. 

Once you create the formula for water clarity the rest is easy.