I'm returning to the hobby of my youth. Killed a lot of fish back in the 70's, didn't know about test kits of water quality back then.
I hope to do better now.
I have a planted 10 gallon with neon/glowlight/x-ray tetras. I just put in DIY C02 last week. The plants seem a bit better, but I lost two fish (c02 poisoning?)
I also have a 30 gallon with a zebra danio, and red-eye tetras. I hope to later convert that to brackish and put in a Green Spotted Puffer. To do that, I'll first have to get the proper insurance for this 120 gallon I purchased, and do a big move over. My apartment landlord caught wind of the big tank and located a Condo/Apt law stating need for insurance....I might just put only 30 gallons of water in it, and do a water/beach scene that is brackish for the GSP.