Pocci poor PE, low mag? K+?

[ultreef]

Everything is doing well in my tank, SPS have great PE except for 2 pocci. Is that a sign that i'm low on something? The usual parameters are good. I can never get a consistent reading with my Elos Mg test kit so I gave up on that. Never testing K+. I do weekly 10% water change.

They were doing great with good PE before, but now when lights are on, the polyps don't come out at all. At night, there is some, but not great PE.

Any ideas?

Thanks.

[jer77]

If your doing WC's once a week I wouldn't be too concerned with low levels of minor elements. If you have a lot of sps i'd just check the cal/alk to make sure. Mg is important with lots of calcification, so getting accurate measurements I say is more important than dosing K. Pocilloporas need strong light and flow. Its sometimes hard to give it the flow it requires while taking care to still use random flow and not blast it all the time.