What's the best way to maintain stable pH in a discus aquarium?

Here is a helpful link: https://www.aqueon.com/information/care-sheets/goldfish Your local aquarium store will likely carry a powdered product to add to the water to increase the pH. The package will have dosing instructions. I hope this helps and please feel free to post any additional questions.

Thanks for reaching out about your fish. Things depend on the difference between the existing water and the future tank. The wider the range, the more stress. Match temperature also, as that provides the most stress. Good luck.

Thanks for your questions about your tank. You have a number of fish in your tank already - a general rule of thumb is 2.5 square centimeters of fish per 3.8 liters. Depending on how large your fish are, you may be close to the carrying capacity of your tank, and you will also need to plan on how the fish in your tank will grow over time (mostly the rainbow sharks). If you are looking for tank mates for discus, it is best to look for fish that are housed in the same temperature zone, and occupy different areas in the water column than they do. Examples would be bottom feeders like cory catfish, those that live on the sides and bottom such as plecos, and those that are in the middle of the water column like some species of tetras. For the question about vacation - I would not recommend leaving your tank for that long without someone checking on it regularly. Power outages can be detrimental for tanks, and water changes or additions would likely be required. Also, automatic feeders also have the potential to fail, and this could cause a large spike in ammonia if a large amount of food was fed, and starvation if there was no food dispensed over a long period. I hope that helps to answer your questions, and thanks for using Petco Pet Education Center, formerly Petcoach.

As a short term bath of up to seven days and a concentration of up to 1 tablespoon/ 1gal water can be used but this is just the fish as a treatment. You cannot add it to the daily aquarium as it will damage the plants and can damage the fish. Remember these are freshwater fish, not salt water.

Yes, in order to have a healthy tank and to give your fish the best environment, it is necessary. Here is a good write-up on the reasons why: https://www.petcoach.co/article/water-chemistry-basics-ph-temperature-water-hardness-waste/

Water conditioning can be complicated and I recommend to stop by your local aquarium store. They are most often familiar with the local water quality and can give recommendations specific to your location. Some areas need buffering solutions to help control things like the water pH. Here are a few links which may help answer some of your questions about water condition: https://www.aqueon.com/articles/freshwater-aquarium-water-quality https://www.petcoach.co/article/aquarium-water-management-alkalinity-vs-water-hardness/ Before moving your goldfish, make sure all the conditions are appropriate for goldfish: https://www.aqueon.com/information/care-sheets/goldfish https://www.petcoach.co/article/how-to-help-your-new-goldfish-thrive/ I hope this helps and please feel free to post any additional questions.

Salt water aquarium requires a great deal of regular maintenance to keep the fish alive. This can be helped by adding live rock (similar to live coral) to the aquarium. Below is a link to some great information for maintaining a salt water. aquarium.http://www.madhattersreef.com/20-ways-improve-aquarium-husbandry/ I hope that helps and all is well with your fish.