Can’t figure out what’s wrong

[ghost2k25]

So I’ve had a reef tank for over 3 months and I keep losing corals, I’ve gotten my nitrates and phosphates tested by a professional and I’ve down it myself a couple of time and they always read really low numbers
1. I can’t get a green star polyps to grow or open
2.montii and chalis coral keeps dying

I have a hunch that my inability to grow chaeto and chaeto die off in the hob Refugium
Is causing something to be released.
Here are some pics

 

[Sniperhank]

Can you tell us more about the system? If parameters aren't an issue it is either flow or lighting. What lighting is over the system? Has the new corals been acclimated to the new light?
What kind of flow is going through the system? Have you tried moving the coral to a new spot with a different flow?

 

[melosu58]

You are going to have some real issues with that tank in front of a window. The sunlight going through is diffused lighting and will cause algae issues. If you are counting on that for lighting it wont work. If you live where it gets cold then you'll get huge temp. swings. It almost looks like you are using sunlight through window as your light and that will not work.