Yes I think your nutrients are out of balance. I also think if you were to dose nitrate (potassium nitrate for example) your phosphate would drop. Your tank is nitrate limited according to the Redfield ratio.
I keep nitrate near 5 and po4s near .02. I have experienced dosing nitrate to lower p04. There are others that have to dose p04s to lower nitrate.
Feel free to pm me and I'll give you my number if you want to talk about it.
I use Hanna ulr and Salifert for p04 and Salifert for nitrate.
This probably explains one of the reasons why some corals don't do well in my tank. Hearing that some nitrates are important has been a real eye opener for me.Ideally, I keep nitrate on my stick tank 5-10 and phosphate less than .05. I currently have zero nitrate and .03 phosphate, along with some stubborn cyano. I'm increasing feeding a touch and syphoning the cyano as I can.
The RR is just too complicated for my hobbyist brainMeasuring things that closely and guesstimating all of the processes/numbers is next to impossible for me.
The slime coat seemed to coat most of the stuff in the sump. Perhaps I was too aggressive with the bio-pellets instead of adding them slowly. Reminds me that nothing good happens fast in this hobby.My guess is the slime coat is secondary to bio pellets. Carbon dosing with vodka, vinegar and other carbon sources leads to these slime coats, IME.
I'm glad to hear that the UV cleared up your tank. You said earlier that your bio-pellet reactor was a recirculating but then you said if you slowed the flow the pellets would not tumble enough. If it is recirculating that will not be an issue. A recirculating reactor has a pump that simply recirculates the water in the reactor and keeps the pellets tumbling. Then there is a secondary pump or tap on your manifold to supply water to the reactor. You then regulate the water coming out of the reactor. Mine is at a slow trickle otherwise it wipes out my nitrates. This would be for ongoing nitrate control. Like you found out you do not want it to be zero and with higher flow across the bio pellets you may struggle to keep nitrates in your tank.
I misspoke, I am using a Skimz bio-pellet reactor. I mistakenly thought it was a recirculation reactor, but it doesn't function in the manner that you described.