High phosphate, 0 nitrates

[Intheflesh]

Hello friends.
I have a 50 gallon lagoon that I am running Zeovit system. (I've been running Zeovit for about 10 years now off and on)
Any who, I have been neglecting my tank for a few months and trying to get it back on track. For the last few weeks, I'm testing my water weekly, making sure I am dosing my supplements per the schedule, 10% water changes, changing my media, etc.

For the last few weeks, my Nitrate has been testing zero, and phosphates around 0.6 ppm (Hannah Checkers)

I'm dosing my carbon Zeobac and Zeostart at half the recommended dosage because Zeo can be a bit aggressive.

I am wondering if I brought my nitrates down too quickly, and that is preventing my phosphate from lowering. Should I try dosing nitrates?

I did a Zeo media change over the weekend, and have been waiting a few days before I tested. I probably will when I get home today to see if there is any change since the media change.

 

[Intheflesh]

Just for reference - this is not a new tank. it has been running for 6+ years. There is some algae growth, corals are growing (slowly) and if anything maybe a little pale.

 

[Uncle99]

Yup, your biological filter needs trace nitrates so zero is a problem. Dose it up if your certain it’s zero.

Or discontinue zeovit for now, raise nitrate and lower phosphate with GFO.

Phosphate removal is a much slower process than nitrate. While some gets skimmed out with bacteria via your micro-fauna, binding it up with a media is more efficient.

 

[Intheflesh]

I've actually been dosing at 50% the recommended dose because Zeovit can be a bit aggressive if you aren't too careful. And prior to starting dosing regiment again ( this was maybe 3 weeks ago) I hadn't dosed anything in weeks.