Thanks!

I still cannot fully part with the idea of discus, but I also know that discus are demanding and I'm not that savvy, and the idea to kill perfect and pricy fish for nothing is not that appealing, so I'll talk myself out of it.

I know that angels do well in vertical tanks, I had angels before and they did well, so why not?

I like tetras, I like barbs, I like corys, I like kuhli loaches, I like botias, so I'll have to decide whether I go with corys or botias, I don't think there will be enough room on the bottom for both. I might want a pair or two of apistos or rams.

I want to make sure that the tank has enough oxygen on the bottom, I know it's a problem with vertical tanks. How do I achieve it? What filter would you recommend?

Discus are a hard fish to take the leap and get. They're expensive (especially because they're schooling fish) and compared to a lot of beginner aquarium fish they can be very easy to kill. It's hard.

However, don't let that disuade you. If Discus are something that you're interested in they're very feasible to care for.

I actually wrote an article today on this (https://freshwatercentral.com/2018/0...-expert-guide/)

But basically if you truly want to keep Discus it's feasible. Just have some things figured out before you get them.

1) Try and stay away from wild caught Discus. I've found them to be more demanding of quality water conditions than home bred Discus. Personally I'm a fan of Kenny's Discus but off the top of my head I'm not sure where they come from. I believe they're imported from fish farms in south-east Asia.
2) Come up with a water change schedule before you get them. They're a lot of ways to cut down how long a water change takes w/ pumps etc.. If you have a sink near your aquarium it shouldn't be hard to build a system where you can do a 45 gallon water change in 15 minutes. Once you get it down to that w/ no bucket lifting etc. it makes Discus seem much less daunting.
3) Copy the breeder. That means ask them what water parameters they use and match them. Ask for a sample of food they use and copy it. Not changing stuff in the Discus' environment makes it much less stressful to have them.
4) Fully setup and cycle the aquarium and practice your water change system etc. Once you fully cycle your aquarium w/ ammonia for example try doing 40% water changes every day for 2 weeks (and keep putting in some ammonia to maintain your cycle). If it's too much then you can know that Discus aren't for you but if you're handling it fine and you have those 15 minutes then you know you can handle Discus.

Thanks!

But in case that I don't go for discus, what would you suggest? What filter, what substrate? How do I get enough oxygen to the Botton of the tank? Will I have enough room on the bottom for both corys and a pair of apistos or rams? Or maybe two pairs, or is it too much?

How do I lower pH without chemicals?

I'm reading your articles, they are really helpful, thanks!

It depends on what you want to keep. I'm a big fan of aqua clear filters but in a hex it might look better to setup a canister filter it depends on where you put the tank and if it's in the middle of the room or against the wall.

For substrate, I've always been a fan of sand. To get oxygen to the bottom of the tank make sure you have some long tall live plants throughout your aquarium and get a few air bubbles at the bottom. Also I'd recommend looking at pumps to get consistent water flow and surface agitation. If you have a aquaclear filter that'll cause some flow and you can put a pump near the bottom of the tank.

You should have room for a school of cories and some rams, I've found rams to be more mid-level fish. Could probably do 2 pairs two.

I'm glad you liked the article

To lower the pH naturally without chemicals try adding driftwood and peat moss.

I didn't get the tank after all. But good news is that my wife and I agreed to give a bit more space for a future tank, so 4' long tank is not out of the question any more. I'm looking for a good deal on 90 gallon or large tank.