Help. Tank unbalanced and losing corals rapidly

[saltyMJ]

I've been battling what I assume to be dinos for the past 3-4 months. I lost every single head on my frogspawn, torch, Duncan, and many more. The only thing still holding on is my hammer and my GSP. Even my purple mushrooms are unhappy. I think I'm near the end of th infestation, the actual dinos have been thinning and are mostly gone. However I can't get my nitrates and phosphates balanced properly. I've tried dosing neonitro, neophos, and reef biofuel daily but nothing seems to make a difference. At one point I got my nitrates up to the 5-10 range but now they are back down to 0. Phos is currently on the rise and at 0.5. I'm almost to the point of tearing down the tank even though the dinos seem to be gone (or mostly gone) all my corals are still shriveled up and dying. I can't see my hammer coral dropping all its head one by one until it's completely gone like the frogspawn did. Any suggestions? Also FYI my tank is a 30 gallon cube and has been running for 3+ years. It's always been a low nutrient system.

Most recent readings;

Calc-340
Alk-7
Mag-1350
Ph-8.1
Salt-1.024
Nitrate-0
Phos-0.59

 

[smitten with ocean life]

@Randy Holmes-Farley

 

[Randy Holmes-Farley Verified Community Expert]

I would dose sodium nitrate, calcium if you have confidence in that test, and do other things to help with dinos, such as uv, silicate dosing, mechanical filtration, reduced lighting, etc.