Question: How to Fix Cloudy Water in a New Tank?
"I purchased a 40 gal tank (fresh water). Washed all gravel, inside of tank, etc. Filled left set for three days added 30 guppies and 5 neon's. Water is cloudy - added good bacteria and still is cloudy. What to do? Thanks "
Cloudy water in a new aquarium is usually due to a condition known as bacterial blossom. When you added three dozen fish all at once, you placed an extremely high bio-load on the tank, which resulted in a large amount of waste being produced suddenly.
Bacteria that feed upon those wastes began to grow in large numbers, resulting in cloudy water.
About Good Bacteria
There are several types of bacteria necessary to neutralize wastes produced in your aquarium. Adding the good bacteria that you mentioned simply added more of the type needed in the first stage of the Nitrogen cycle, which you already have in overwhelming numbers. Don't add any more of those bacteria, as you don't need them. Adding them at this point is like squirting lighter fluid on a fire. Also, don't add any more fish, as you are way overloaded for a new tank. If possible I'd move some of the fish out of the tank until you get things under control.
Your biggest issue now isn't the cloudy water; it's the ammonia spike that will soon occur (if it hasn't already), followed by elevated nitrites. Both could result in the loss of some or all of your fish. I'd strongly recommend that you become familiar with the Nitrogen cycle, so you are aware of what will be happening in the upcoming weeks.
You should begin testing your water right away for ammonia and take appropriate steps to keep it below lethal levels. Hang in there; once you get your tank through the initial cycle the cloudy water problem will clear up.