I just restarted my tank after my goldfish died 5 months ago. Cleaned it did a water chamge. After they died i kept a dwarf frog in the tank. Fast forward to yesterday. I have been doing small water changes. I tested my water levels. Ph was at 7.3 and ammonia was at 4+. This is on a 30 gallon tank. Did a 15 gallon change last night and rechecked it today. Ammonia was down to 2 and ph is down to 6.8. What are the next steps to get the levels down. Im now at a loss of how to get them down. Thanks for your advice