Why is my hammer coral doing this?

[Just John]

Even though it has not been in heavy flow, the tentacles on the back/downflow side are growing longer. Why?

 

[Dread Pirate Dave]

Even though it has not been in heavy flow, the tentacles on the back/downflow side are growing longer. I have another next to this and it has done the same thing. Why?

It seems like there is a lack of decent back and forth flow. Maybe that would help.

 

[Just John]

Unfortunately, I don't think I can put in something so my tank has back and forth flow. it's just13 gal.

 

[Tikki]

Pic isn’t loading for me but could it be fighting/sweeping?

 

[Just John]

Pic isn’t loading for me but could it be fighting/sweeping?

It doesn't look like it, On one side the tentacles are just longer. If the flow stops, they just hang down below the others.

 

[Mr. Mojo Rising]

I don't think it is getting enough water movement, my hammer polyps jiggle non stop.

 

[Just John]

I don't think it is getting enough water movement, my hammer polyps jiggle non stop.

I agree that the flow is low-ish compared to others I have seen, but this one appears to be growing as if the flow is too strong since the tentacles in back keep getting longer. It makes me reluctant to give them more. I have no clue what is going on.