Nitrate is the lower the better. Typically people aim for below 40ppm, but it is ok if it is slightly higher given that the nitrate concentration went up gradually over time instead of a sudden spike. Unlike the toxic ammonia and nitrite, nitrate is harmless but at too high concentration it is said to be able to lower the immune system of the fish which can make them easier to catch diseases and parasites.
If your new filter is rated for tanks way above 60 gallon, then you should be able to run it alone. Although I have said you can never have too much filtration. It is entirely up to you if you wish to run two filters at the same time instead of just one. There are quite some people using multiple filters for the same tank out there. It keeps more stable good bacteria colonies in case you accidentally did some damage to the good bacteria colony in one filter while cleaning it.
No need to get any bottom feeders for "cleaning".
First, they are tropical fish. They do not belong in the same tank as goldfish.
Second, all these so called "cleaning" fish do not really clean anything at all. They might chew on the algae here and there, but they will actually feed on the sinking fish food at the bottom. A lot of people mistake them for eating other fish's waste. Nope, they don't. By having them in your tank, you will need to add a sinking food and it will add to the bioload in the tank. More ammonia if I simplify the result for you. The job of cleaning the algae on the side of the glass should be yours anyway. Do not depend on the fish to do the "cleaning".
The job of cleaning the algae on the side of the glass should be yours anyway. Do not depend on the fish to do the "cleaning".
