Whats the best way and fastest way to get my nitrates up, feeding is the only thing I can think of.
Sodium nitrate, potassium nitrate, or calcium nitrate. Any of these will work, and most you can find on Ebay.
I have agricultural grade calcium nitrate, works fine if I ever use it. I think a 5lb bag of it was like $10 and it's more nitrate than you'd ever need.
Dosing it is VERY tricky b/c you don't know for sure how much a teeny pinch will raise your nitrates in the tank.
With a little math and testing, you can figure it out.
Do this:
First buy the Salifert Nitrate kit. It reads at VERY low levels, and high levels, which is what you'll need. It's a very good kit.
Add 1/8 tsp (or 1/4, whichever you have a measuring device for) to one gallon of RO/DI water. This is your NITRATE SOLUTION that you will dose from.
Test nitrates with whatever kit you have. Should be off the charts.
Add one teaspoon of this NITRATE SOLUTION to a different gallon of clean RO water. Mix well. Test for nitrates. You should get a reading. If not, add another teaspoon of the NITRATE SOLUTION to the gallon of test-water.
Now you know how much NITRATE SOLUTION you need to raise one gallon of water to whatever number you got.
Now, to figure out how much you need to dose into the tank. Let's say, for example, that ONE teaspoon of NITRATE SOLUTION raised the gallon of clean water by 1ppm.
If your tank holds 100 gallons, you'd need 100 teaspoons of NITRATE SOLUTION to raise your water by 1ppm.
I do not recommend you raise it more than 1ppm per day. I don't recall how much the OP used per day.