Brown algae (diatom) outbreak

Hey everyone, I've had my tank up and running for about a month now.
At first I had lil bits of diatoms showing on the sand and non-live rock in very small quantities but that was fixed by adding more sand sifting snails.

Recently I've had a huge outbreak of brown algae on my non-live rock and my sand bed. It has happened after I got my 4 chromis. I have a number of different sand sifting snails as well as astrea snails going around on the tank walls. Also I've been noticing for the past 2 days there is a flaky material coming out of my sump return flow back into the water. They arent micro bubbles, they look like a very very small flake. The green chromis in there seem to pick at it then spit it out.

Just wondering if anyone has any suggestions. I know my lighting is poor at the moment, only 6500k, I am awaiting my 10k/actinic t5 fixture in the mail. I have a koralia 750 and a nano koralia creating flow in the tank. Dimensions are 24" wide x 24 " tall x 18" deep .

Thanks!

also, the chaeto in my refugium doesnt rotate at all, and I can't tell if its growing since I got it a week ago or not. Should I put the nano Koralia in the sump/refugium and try and position it to increase the flow and make the chaeto spin?

tetraking: what type of conditioner are you talking about?
canuck: with the flow in the sump, ive heard mixed opinions about wanting flow to be low in a sump as opposed to fast, but I know its better if the chaeto rotates in the refugium. What do u think? think the nano koralia would work? Ill try and take a pic of my sump tomorrow and post it. THx guys , a lot!

Fleshy, thx for the welcome from Madison. The sump/refugium was not used before, it was custom built for me. I have no idea what the flakes are. Hopefully when my protein skimmer comes in, itll take care of it.

well I tried getting the flow in the refugium to make my chaeto spin using the nano koralia, annnnnd it didnt :/ i moved it all over in different directions and it just moves it around not causing it to spin. So I don't know what to do about that, canuck maybe you could put a picture up of how you did it? Annd the flakes are definitely coming from the bottom of my sump, they are lil white flakes and i can see them in the return area too getting sucked up into the main tank