Juwel 120 LIDO
32 gallon
Setup a while back with plants, drift wood and a few rocks
i add plant fertiliser daily
Bioflow 3 M, changed regularly

Initial inhabitants (all still small with a plan to rehome to a bigger tank when start growing)

2 german ram
2 golden ram
2 balloon ram
3 guppies

3 weeks ago, bolivian ram, 3 glass catfish, 2 phantom pleco, 6 rummy nose tetra added

On Sunday 6 rummy nose tetra and 2 rainbow fish added, a few plants added

on Tuesday, rummy nose tetra dead, additional drift wood and air stone added (pre soaked prior to going in)
on Wednesday rummy nose tetra dead, 20% water change, RO to soften
on Thursday, today, glass catfish AND balloon ram AND golden ram dead!

What is wrong?
There is no major aggression in the tank, all coexist ok.
Temperature 29C, no traces of ammonia, nitrates, everything on the water strip seems fine!
Feeding once a day, alternating between warms and flakes
My heart is breaking!

HELP!!!