Powdery brown stuff

No, it didn't start when I started useing the Prime. I have only been useing it for the last week and this has been going on for a while.
I was useing Prime to help get my nitrate down because when I tested my DT water it read over 100. I don't know why, the only thing I could think of was a turbo snail had died but I wouldn't think that would be that big of a die off but I removed it anyways.

 

The only things that will get your nitrates down in your tank are: 1) frequent water changes. 2) Coiled denitrators of similar filter type. 3) Algae, such as your "powdery brown" algae, and 4) Some type of macro algae or plant.

And a nitrate level of 100 is WAY too high for anything in your tank. I'd get on the water changes ASAP!

 

It is no longer 100. It was at 100 a couple of weeks ago and then I did a water change and added Prime and it dropped to 20.
I do have macro algae like stated earlier. Chaeto.

 

There is a product called Nitrox its simply zeovite crystals like rocks just add them to your filter somewhere to pull out the NO3 if you do not use a coil . Some places pack this rock into a filter to sell .. Its not a permanent fix as it has to be replaced every so often but its very effective .

 

Ok thanks for the suggestion.
We don't have any LFS except Petco so ill have to order it online.