Am I doing something wrong? (SPS Coral, pic)

do you have a sandbed?

I am thinking phosphates but I also think they are being absorbed fast enough by the sandbed to not be an issue for the acros. even without testing for phosphates you cant tell when they are high or low by algae growth alone. PO4 levels should be kept at .003 ppm or below

 

The bulbs may be the issues as I am still running my stock bulbs on my Aquatic Life 6-bulb, will be replacing the bulbs here in the next few weeks. Bulbs are about 4 to 5 inches from the water(standard mounts) No Glass lids.

I do have a sand bed.

I am running bio-pellets. But even before bio-pellets i was running GFO/Carbon and the coral had the same issue, growing well but only purple tips.

 

I'm thinking nutrients too...the pink BN's looks a little more brown to me than it would in an ULNS. That said, blues and purples can be the hardest to work with...purple tips may or may not mean the rest of the coral could be purple...getting the base to turn purple will require very low nutrients and most likely some specific dosing of amino's and possibly some potassium...purple acro's also seem to prefer higher K lighting...many of the tanks I've seen with stunning solid purple acro's are more in the 20K range.

 

Could be Phosphates or you might need more of a blue spectrum of lights would help as well. But a lot of times if the tips are bright and the base is brown it could just be a brown acro.

 

I think you'll get better color with your purple acro by switching to better lights. I suggest ATI Blue+ in three of your t5's. Nutrients probably arent much of an issue look at your blue and green acros but you might want to try a little GFO in a reactor if the new bulbs dont help.

 

Also from an uber technical aspect some reef enthusiasts maintain increased levels of Iodide and Potassium for purple SPS. Way too much input for me. Theres are great article on SPS coloration out there I dont have any links off the top of my head though. All being said they look really healthy and for me thats usually enough ;-)

 

Thanks for the input! Waiting for the BRS group buy to fill up and new bulbs will be on the way.

 

Dude, that is definitely your bulbs. I have an aquaticlife fixture as well. And those stock bulbs are terrible IMO. Way too much WHITE overload. Not saying you won't get good growth, but moreso the colors of your corals. I switched to geissmenn bulbs, and my once brown looking corals suddenly looked different. You will be amazed at the difference if you go with the ATI's.