Nutrient balance struggle.

[bfortune76]

I’m really struggling with getting a balance with nutrients. I can’t seem to crack the nut on this one. My reef is a 4 year old mixed reef. Save for one LPS that I struggle to get to color up my LPS are all fine. Easy SPS like birds nest are also fine. Acros are hit and miss. Some are thriving with PE and others are just “ok”. For filtration I have a 40g sump with a reef octopus 150 classic, a turbo aquatics algae scrubber, and a reactor with carbon. I have 70g total water volume and about 150 lbs of live rock. I’m dosing BRS 2 part, I feed 1/4 teaspoon of reef frenzy every 4 days, I feed 1/4 teaspoon of pellets and 1 teaspoon of homemade frozen blend daily for fish. Until recently I struggled to get N and P to readable levels. Now that I have a better No3 test kit I get slight N readings and since starting with reef frenzy I’m starting to get P readings as well. Here are my numbers

2x OR T247, 20 white, 90 blue

79 degrees F
1.026 (Milwaukee refractometer)
CA 420ppm (Red Sea)
ALK 8.4 (salifert)
MAG 1400 (Red Sea)
Po4 .04 (Red Sea)
No3 1.5 (Red Sea)

My red monti is my indicator coral. When it starts looking bad I know something is off. And both are starting to turn white in the center. I normally attribute this to alk swings but my alk is dosed in increments through the day so it’s pretty solid. All I can think of is my N is too low but I can’t get it any higher with out dosing and I prefer not to dose nitrate. I have some acropower amino acids coming this week and I’m hoping that will help but I’m out of ideas. Just another note, since my P has started rising my nuisance brown hair algae has started going away and is nearly gone completely. Which I thought was interesting. I also have a lime green and reddish brown cyano bloom I have been trying to get rid of. It has also gotten better since the P has gone up from 0 readable to .04.

 

[reefgeezer]

IMO, any available (measurable) N & P is sufficient. I wouldn't chase a nonexistent "balance". The reduction of your "brown" hairy algae could be due to the competition for limited dissolved organics with the Cyano. That might indicate that the dissolved organic (DOC) level is too low. Your corals need the DOC also. Skimming & GAC are pretty effective at limiting dissolved organics if the input isn't very high.

I'd feed more for a while and see if that helps. Reducing the GAC and running the skimming drier can also make the filtration less effective and allow a little higher DOC level. Amino acids can help also, but get kinda pricey.