Bingo, there is the little devil
PO4!
Do a heat test at that level and it will be higher than that.
First thing important here is regular water changes, what is happening by doing such staggered changes is the PO4 is leaching into everything it can including the live rock, in fact your live rock is one big yummie PO4 bath right now.
You need to do at a one off 25% for two weeks followed by weekly 10%.
The Ultra Life and the Ultra Bio will help significantly in skimming out all the nutrients, but this will not be a quick fix under no illusion.
If you are game I will send you the Ultra Life and Bio, but you will need to be strict in following what is recomended.
LMK
