Monti Cap not growing

[Jmcg89]

Hoping for some insight why my montipora cap isnt growing and the acropora right next to it is?
Tank is fairly new 4 months but the acropora in that pic was a plain stick when i put it next to that montipora.
My alc was a little hard to pin down but has been stable a couple months.
Have a gha problem that is getting better but had nitrtates and phos undetectable with salifert test.
Acans, anemone, acro, pocillopora, digitada all grow and zoas and this montipora cap struggle.

Ph. 8.2
Mag 1260
Calcium 390
Alk 8.2
Temp 78 to 79
Nitrate and phos. Undetectable

I feed a decent amount with rods and mysis.

Thank you!

Its under a reefbreeders 24 at 75 percent blue and 20 white max. Hung 10 inches high with the coral maybe 18 inches underwater.
It gets high flow from a crossflow wavemaker

 

[Jmcg89]

I wouldnt be suprised with a lack of color from the low nutrients but could that cause very slow growth too?

 

[Dkmoo]

Calcium is a bit low. Also you want a little bit of no3 and po4 for nutrient.

Do you have actual par numbers? Generally speaking montis need less light than acro. Looks like the monti you put higher than the acro? So if that acro is growing well then maybe its too much light for the monti. It does look a bit bleached, but not sure if that's bc its getting too much light, or not enough no3/po4.

 

[Jmcg89]

I dont have par numbers unfortunately,
The tips of that acro are like mid level of the monti so its very similar light

 

[Dkmoo]

Also, are you sure it's not growing? Not all montis grow that "cap" and even the ones that do often don't grow the way you want them to (depending on the light and flow". It looks to me like that monti has grown "downward" and already encrusted the frag disk and made its way to the rock underneath? This might not be the "shelfing" kind

For ex, here are my 2 montis. The red one is supposed to be the "shelfing" kind but it decided to just grown curve down and grew a "skirt" around the rock edge. The green one just encrusts in the rock base and that "shelf" you see hasn't changed in 3 months.

 

[Jmcg89]

Also, are you sure it's not growing? Not all montis grow that "cap" and even the ones that do often don't grow the way you want them to (depending on the light and flow". It looks to me like that monti has grown "downward" and already encrusted the frag disk and made its way to the rock underneath? This might not be the "shelfing" kind

For ex, here are my 2 montis. The red one is supposed to be the "shelfing" kind but it decided to just grown curve down and grew a "skirt" around the rock edge. The green one just encrusts in the rock base and that "shelf" you see hasn't changed in 3 months.

It is actually growing very similar to that red one you have. It's just insanely slow

 

[vetteguy53081]

Calcium a little low (take it to 440) and elevate it higher in the tank. Moderate light and water flow and assure Phos and nitrate are Not high