Was the rock ‘dry’ live rock or real (wet) live rock?
What media do you have in the HOB filters?
Has the tank been cycled and, if so, how did you do it?
Do you have a LFS nearby where you can get some RODI water or pre-mixed?
I am not an expert, but the first things I would do is to stop water changes and turn the light off. I would then try to get some water of known quality (from your LFS) and do a water change with that, instead of the water you have been using. I might also add some media (e.g. GFO) to the HOB filter to get the Phosphate down, as 0.25 is a bit high.
What media do you have in the HOB filters?
Has the tank been cycled and, if so, how did you do it?
Do you have a LFS nearby where you can get some RODI water or pre-mixed?
I am not an expert, but the first things I would do is to stop water changes and turn the light off. I would then try to get some water of known quality (from your LFS) and do a water change with that, instead of the water you have been using. I might also add some media (e.g. GFO) to the HOB filter to get the Phosphate down, as 0.25 is a bit high.