are there beneficial bac.i can buy?cloudiness will not go away

Question
my six month old tank, will not clearup,it has 5 large fish, in 50gal,the milky cloud will not leave, i do water change,20% 3-4 TIMES A WEEK.salt in tank,1tea.per gal
so i'm hoping i can add beneficial bac.from a source
                                     thanks tony

Answer
Hi Tony;

What kind of fish are they?
How big exactly?
How often do you change water?
What kind of foods do you feed?
Hoe often do you feed?
How long is the food in the tank before the fish eat it all?
What kind of filter?
How often do you clean the filter?

Followups Welcome

At Your Service;
Chris Robbins