sudden diatoms.

Good morning,

The tank is a 75 with a 30 sump, the rock is from my old 55, and the sand is new. It is roughly 5 months old with the only new additions being 48" reefbreeder light from marine land marine pro(both added 1 month ago). The marine land had 4 54w ati blue plus and 4 leds I didn't run the 2x250w hqi's. The other addition was a brs gfo reactor, running both carbon and gfo, that is currently out of the tank. I started to read 0 ppm on my phosphate test so I took it out as not to strip to much nutrients. I do a 20 gal water change every 2 weeks. I vacuum the sand and take about 5 gals out of the sump vacing any detritus, and clean my skimmer neck every week. Top off water is Ro/Di made from my spectrapure unit. I read 0 tds out of the unit and out of my storage container. Skimmer is a reef octopus sro-1000, and I run a oxydator. my photoperiod is from 9am to 8pm, with my peak being 45 blue and 35 white. the feed schedule is a small piece of nori once a day and Mysis Tuesday and Thursday, and reef energy once a week. I have had a diatom outbreak since I added the brs reactor, change the light schedule to the current one being the previous schedule was like 14hrs, and feeding was reduced as well. The only two thing I have going on is the diatoms and my couple pieces of xenia are shriveling up and dyeing. Any ideas?

Fish
1 one spot fox face
1 melanurus wrasse
1 Leopard Wrasse
1 Coral beauty
2 chromis
1 cleaner shrimp

Coral
xenia
green leather
monti
acans
favia
chalice
lobo
open brain
torch
blasto
hammer
frogspawn
zoas
mushrooms
gonipora

Parameters
SG 26
temp 78
phosphate 0
Nitrate 4ppm
nitrite 0ppm
ammonia 0ppm
calcium 400