I thought I made a post on this website, apparently not.
Anyways, here's my thread, I'll simply post a link to the playlist for my tank.
Long story short:
Our 4.4 tank started out with 4 adult male guppies and 7 babies. One guppy killed one. Then due to snails we added a betta to an already heavily stocked tank. Well... did a massive water change with DI water (oy vay) lost many guppies. Did another massive water change, lost the remaining females.
Now it's a 4.4gal betta tank.
We're having some issues with water quality, I think mostly from it not being a mature system and I don't do water changes frequently enough. I've recently started cleaning the sponge with tank water with every water change too so I'm hoping that will eventually help with things.
No, I'm not still using DI water with water changes, just detoxified tap water - I haven't tested our tap for phosphates or nitrates... I wouldn't be surprised if they're in there.
Here's the playlist link, thanks for watching!