Salt is a whole other level of maintenance. On a 10 gallon watch water lvl and fill daily with distilled or RO
water. The salinity will change drastically with evaporation. If the sailinity changes, everything changes. Water evaporates in a Fresh water tank and it has much less bearing on livestock. Also once cycled, I would recommend fish only for 6 months. Coral and invertibrates are very sensitive to changes where fish can usually handle much more. If you didn't test water before, you should now. There are more variables and items that need to be maintained, like salinity, pH, phosphates, magnesium and alkalinity. Fresh water fish and plants can usually survive pretty well on just water changes.