Low nutrients slowing LPS growth?

[Mebbid]

I currently have a 20g mixed reef and have abysmally poor growth rates on most of my LPS corals. My Duncan looks great and healthy but hasn't grown a new head beyond it's first since september. My torch and frogspawn that were bought at approximately the same time are in the same boat with the duncan.

I first thought it was my alk, calc, and mag (which it was) but now that I have those levels under control the growth rate is still really poor which is making me think about other things that could be the cause.

My parameters hover around:
Nitrate - 0
Phosphate - 0
Calcium - 400ish
Alkalinity 11dkH
Magnesium - 1200
Salinity - 1.025

Equipment:
120w LED light
10g refugium w/ grape caulerpa and chaeto
no reactors or skimmer

Stock:
Snowflake blenny
2x Occ clowns
Kaudern Cardinal


Using an API test kit I haven't had a single positive reading for either nitrate or phosphate in nearly a year. However I recently bought a salifert phosphate kit and it tested at 0.0. The other readings are taken with a red sea test kit.

I feed 4 - 5 times a week with frozen mysis and twice a week with some nori for the blenny.



Would you think that it's my low nutrients that's the cause or should I look at other things?

 

[54seaweed]

shut off the skimmer a few days see if you see any difference
how often you do water changes

 

[Macscale]

shut off the skimmer a few days see if you see any difference
how often you do water changes

Doesn't have a skimmer.

 

[Mebbid]

shut off the skimmer a few days see if you see any difference
how often you do water changes

I change about 20% every other week.

 

[Redwolf91]

Stupid question, but is there proper flow on your corals?

Sent from my Z750C using Aquarium Advice mobile app

 

[Mebbid]

Yessir.. I have about 30x the tank volume hourly in flow.

 

[Redwolf91]

Ah, then yes, you have enough flow. Tried moving them into higher/lower flow to see how they respond? I have had to move some multiple times to find their happy place

Sent from my Z750C using Aquarium Advice mobile app

 

[BigRedsReefs10]

I've always found lps seem to like the water a little dirty, try brodcast feeding some mysis a few times a month and let your trates and po4 climb a little (~ 5ppm ish and .05ppm ish respectively) is about what I keep my lps systems at

 

[Mebbid]

I've always found lps seem to like the water a little dirty, try brodcast feeding some mysis a few times a month and let your trates and po4 climb a little (~ 5ppm ish and .05ppm ish respectively) is about what I keep my lps systems at

I actually feed my fish half a cube of mysis 3 times a week with flake food in between. My macros keep my nitrates and phosphates bottomed out.