Algae or something becoming an issue real quick

Water params are stable, this tank has never really had any major issues except for diatoms in the beginning tanks over a year. It seems it's starting to grow and aggravate the corals

I run Gfo & do twice a month water changes of 10 percent I can up this, just never really had a need to

Temp 79
Salinity 1.026
Ammonia 0
Nitrate 0
Nitrite 0
Phos 0
Mg1300
Ca 460
Alk 12

I did in the last month rid the tank of hermit crabs but have a fairly large crew of snails twice reefcleaners recommendation

Only new thing is been feeding new era algae pellets once every few days fish love it

Where do I go from here? Add more cuc? Up water changes? New Gfo or something like phosguard

 

Forgot to add pics and describe it

The algae is like a light brown and on the sand and rocks . Most of it popped up in the last 2 days

I also last month added 2 additional koralia 1400s there was a lot of adjusting and a good deal of the sand was kicked up

Also I use ro/di and this is the only tank of mine having the issue.