SPS struggles

[mseepman]

I was wondering if any of you SPS specialists had a tip for me on ways to better keep Acros.

I have a 70G mixed reef...and there are a variety of softies, LPS and SPS in the tank. My SPS usually does quite well, but I understand that mixing them with softies can make the job tougher.

Here is my issue and this only happens to my Acros. They will grow well for a while and then out of the blue, I will come down to my tank and see that the tips are growing algae. Eventually it will take over to the point where I need to trim back the coral and then things will be okay for maybe 3 weeks and it will start over.

When I get a new Acro, they might be fine for months, but then the algae on the tips happens.

I have a variety of other SPS and all of them are growing well and have been for over a year.

Here are my numbers:
water quality
SG 1.025
PH=8.2
Po4=0.01-0.05
No3=1
KH=8.5
MG=1200-1300
Ca=400

Any suggestions would be graat Thanks.