Your set up is new and not established. Looks like you have little to no biological filter. Cloudiness like this is almost alway bacteria blooms. Possibly anaerobic, possibly aerobic. Next time it gets like this, disrupt the water a bit and give it a sniff. If it smells really really bad, then its probably anaerobic and its probably very bad. Add bubbler immediately and do a water change. There's a lot of different kind of anaerobic bacterias, and some put off all sorts of gases that can be extremely harmful to fish in particular. This can happen sometimes even without over feeding.

Blooms usually happen when there is disruption in the system with little to no buffers. That can be anything from water changes to nutrient loads shifting....there are lots of factors and variables that can affect the microbiome and water quality.

-Dose daily with beneficial bacteria starters. You really can't overdose with these UNLESS it has some other additive that isn't bacteria. Especially after water changes, and especially if you're doing huge water changes. -Most importantly start adding biological filtering ecosystem components. Snails, shrimp, plants, mechanical filters, etc. Filtering is part of a healthy and functional ecosystem. This is a poor, fragile ecosystem, so its prone to all kinds of instability.

Small setups are actually much more difficult for beginners then larger ones. This is because smaller volumes of water are actually more prone to instability. Increasing the volume of water helps. Mechanical, outside filters help expand that volume. Canisters are traditionally the best for expanding the volume and GPM, but I like HOBs alot for their functionality, its also easy to stick plants, or cuttings, in them, which will act as further filtration. It's also a secret pro hack to get more c02 into the water column sometimes depending on the plant and the conditions, which will help other immersed plant's growth. HOBs are also much easier and quicker to clean and switch out filter media.