Hey guys,

I bought an empty 72 bow front about a month ago off craisglist. I cycled it and then added some neons, guppies, danios, cory, and fox. I wanted to add some discus but now I'm nervous and think I should have sanitized it and started with the discus first(8 of the fish I added died). So I've been reading on here about how to sanitize it. The two options I like best are the bleach and hydrogen peroxide. I'm not sure where to get hydrogen peroxide at 30% so I'm thinking bleach is the easiest. I'm wondering if this method is safe for my equipment? I have a penn plax 1000 and a hydor inline heater.

So I would like to remove the substrate(its pretty ugly and I want to get something different) but leave all the equipment hooked up and the fake plants, wood, decorative rock inside. What ratio do I use? I first clean the canister media to remove all the accumulated gunk, run the water/bleach for 24 hours, drain, rinse, drain, and then let it dry? or do two rinses to be safe? How would i know the heater is dry and bleach safe? When I remove the substrate all the accumulated waste is going to be floating around, should I empty that water and do clean water or does it really matter?

After a few days of drying I can add the new eco-complete substrate and do a fishless cycle? I've never done fishless. So I add ammonia to the tank to simulate the fish, how much, how often, and for how long? I'll test the water everyday and once I see nitrates and no ammonia I'm good to add the discus? My tap water has nitrates so I'm guessing I'll look for elevated levels of nitrate above the tap water level? It would be ok to start with 6 medium sized discus?

Thank you so much for the help. Ive been reading and reading, but I see sooo many different opinions I feel pretty confused. Oh, I'm not completely new to discus its just been 13 years and bumpy road to remembering it all haha