Acropora in moderate nutrition water

[zsxking]

3 weeks ago, I got some pink acropora and acropora nana frag in my nano tank, which water is usually sit around 5~10 nitrate. It is only running a Lee counter current protein skimmer, efficient but surely not considered heavy skimming. I was planning to upgrade to a better Skimmer, probably BH-1000.

But since last week I notice both of the acropora are start growing. That should be a sign that they are doing good, right?
Acropora nana:

Acropora pink:

But one concern is the nana never extended its polyps. I watch it at night everyday, never. Is it normal that it never extend but growing?

As my understanding, ultra low nutrition system is just one of the ways to run a reef tank, but not the only way. Does anyone has experience with SPS in a not so low nutrition system? I am thinking leaving the tank how it is, as it is working fine. What you guys think?

 

[Jettareefer]

I have had some acro's that take a few weeks to fully extend, if they are growing they are happy!

 

[Reefer54]

that acro pink in the second pic looks like it has some tissue loss at the base and tips....or are you showing that the white is growth.....i hope i do not offend you, i am curious.


but fwiw, sps can be kept in all sorts of conditions. ULNS have become a proven way of keeping them as the water quality tends to be more stable and predictable....more nutrient laden systems fall subject to specific nutrient buildup and become harder to control when "x" threshold is crossed. And yes, if your corals are growing, that is often accepted as a "good" thing around here......if they were spawning, sometimes better, sometimes worse.

 

[zsxking]

Actually I am not sure if the tip is new grow, forgot to take picture when got them. But the bottom surely is. Because it was wrapped in epoxy when put into tank, but now it's over the epoxy. As they look the same, I think the top is grow too. On the back side there are two small heads rising too.