Your ammonia is above the danger level of 0.25. However......
Since your tank is so big, I'll tell you a better way to judge when a water change is due - but only for ammonia, not nitrite.
Ammonia exists in 2 forms in water, ammonia and ammonium. It's only ammonia that is very toxic, ammonia isn't nearly so bad. Our test kits measure the total amount of both forms combined, but there is a way to calculate how much of that total is in the very toxic form. You need 3 figures and
this calculator. The three figures are the ammonia reading, the pH and the temperature of the water.
Enter your ammonia reading in 'total ammonia measurement' on the left side. Set salinity to zero. Enter your pH and water temp then click calculate on the right hand side. You want the bottom number, NH3 Concentration.
I have just entered ammonia 0.3, pH 7.5 and I've assumed the temp is 25C. This gives an NH3 concentration of 0.0054. Anything below 0.02 is safe, and you are below that figure.
Keep testing every day and entering the ammonia reading in that calculator. As soon as the NH3 concentration reaches 0.02, you need to do a water change.
But at the same time, monitor the nitrite level. There is no non-toxic form of nitrite. You need to do water changes to keep that down.