Updated tank photo, everything went a bit wrong with the tank *sigh*
I've had something wrong with the fish, I think there's a bacterial infection in the tank. I've lost all but one of the rams and one of the angelfish and all but one of the otos. Also lost Limpy my pushing 7 years old cherry barb but that was expected (he had a stroke or something 3 years ago and has been paralysed in one side since then, I expected him to be a goner way back then, so him surviving an extra 3 years was remarkable)
I can't get actual antibiotics without a vet prescription in the UK so I tried a few different medications I could get my hands on (over a period of time) and that melted my vallisneria down.
I did a mini rescape to declutter the tank abit also with only the one ram it's less important having line of sight breaks etc.
I still have vallisneria at the back, the roots survived and it's starting to grow back.
I've measured the water through all this and it's come up fine in the tests. Got myself a TDS meter as well and that sits at around 140 so that's not too bad. The fish that got sick stopped eating, lost colour, then got mild fin rot and hung around listlessly and the ram got an infected lip. I have no idea what went wrong really and don't really want to dwell on it. The otos seemed to have too red gills as well. Not going to add any new fish for a while now.
I sort of want to change out my substrate, but I know that's a huge pain
12 penguin tetras
1 german blue ram
2 neon tetras
1 cherry barb