Dear Micky06,
Goldfish, even beautiful Orandas and Black Moors, have a large bio-load. The usual rule for fancy goldfish is 20 gallons for the first and 10 for each additional one. I am going to assume that both are young so you may be able to have them survive in a 20 gallon for a while, but you will need a 30 gallon soon--just for the goldies. The footprint for a 30 is not that much larger than a 20 so you might be able to find the space. I am not familiar with your filter, but goldfish are happier with 10 X gallon/hour--or 200 gallon/hour for a 20 and 30 gallon for a 30. Goldies like airstone and other ways are adding motion to the water.
While they are in the 20 gallon, daily water changes may be necessary to keep ammonia and nitrites at 0. Your nitrate reading is good. Good luck,
Chris+