How do you get enough nutrients to color up SPS without exploding nuisance algae?

[PedroYoung]

This may be a better question for the chemistry forum, but I've always "struggled" with low nutrients (can't get NO3 and PO4 above 0-0.01). I still have persistent turf algae. My SPS don't color up as well as I'd like and I'm convinced it's due to low availability of NO3 and PO4. I've tried to increase those values by discontinuing export methods and even adding supplements. At the most I got NO3 up to 3 ppm and PO4 up to 0.04 ppm but had explosion of hair algae that overtook the corals I was trying to color up (they did color up before being overwhelmed). Not sure what the answer is. How to feed corals and not Algae????

Tank Details
200G mixed reef
3x Radion G6 Pro's running modified Blue + at about 350-400 PAR in SPS zone
Alk typically 8.5
Ca typically 450
Mg typically 1400
NO3 typically undetectable
PO4 typically 0.1 - 0.2 ppm
Run fuge about 8 hrs/day
skim fairly dry with Verex A200
run GFO in reactor
Currently using Red Sea salt

TankPAR by Peter Young, on Flickr

Untitled by Peter Young, on Flickr

Untitled by Peter Young, on Flickr

 

[Lavey29]

Why run GFO if you are trying to raise nutrients? How much do you feed your fish daily? Frozen raises nitrates, pellets raise phosphate. Have you done a recent ICP test to check everything? Trace elements can affect coral color to. What does your cleaner crew consist of?

 

[Reefer Matt]

I keep a lot of cuc like urchins and snails.
NO3 is always >25 ppm, but PO4 has to be dosed to keep it from bottoming out. It is kept around .05 ppm. Just gotta have mouths to eat the algae before it grows out, in my case. I feed high protein flake food to the fish.

 

[PedroYoung]

Why run GFO if you are trying to raise nutrients? How much do you feed your fish daily? Frozen raises nitrates, pellets raise phosphate. Have you done a recent ICP test to check everything? Trace elements can affect coral color to. What does your cleaner crew consist of?

When I stop the export methods (refugium and GFO) the turf algae explodes. I do Triton 4x year and everything is always in green. CUC is mostly snails and tangs

 

[PedroYoung]

I keep a lot of cuc like urchins and snails.
NO3 is always >25 ppm, but PO4 has to be dosed to keep it from bottoming out. It is kept around .05 ppm. Just gotta have mouths to eat the algae before it grows out, in my case. I feed high protein flake food to the fish.

What urchins do you keep? Any crabs? I’ve thought about bumping up my CUC

 

[Reefer Matt]

What urchins do you keep? Any crabs? I’ve thought about bumping up my CUC

I have pincushion urchins. I don’t like crabs because they would usually eat my snails.

 

[exnisstech]

IME high N and P have nothing to do with nuisance algae. Any time I have nuisance algae it has been in a tank with low levels of N and P, at or close to 0. I wish I new exactly what the causes are but it has never been elevated N and P. I have one tank that runs NO3 25 - 40 and PO4 0.4 - 0.9+ where my tester maxes out and i have zero nuisance algae.

That tank is a move from a 180g that ran similar levels with no algae problem.
That said in my SPS tank I have to dose ammonium bicarb to keep N above zero and PO4 runs 0.02 - 0.03 but I have had to dose PO4 also when I see test results of 0. No algae in that tank either.

I'm still trying to figure out why I have an algae problem in this tank. It too runs very low N and P requiring I dose to keep levels above 0. Algae grows on corals, clam and snails shells and it loves the back wall. I scraped the back a few days before tanking this pic.

I don't have an answer as to what all the causes of nuisances algae is. I think all dry rock can contribute as well as lack of herbivores and I'm sure other things but in my tanks it has never been related to higher levels of N and P

 

[rtparty]

Have enough herbivores to handle the algae

 

[bobnicaragua]

As soon as I start seeing algae, I add more snails, hermits, and long spine urchins.