Cause / Cure for red slime algae

[jasper24]

I have what I think is red slime algae in my sump. It is a red / maroon film that is slimey and easily rubs off. I do not have any in my display. What is the cause and fix for this? I make my own water using an ro/di that reads 0 tds and use reef crystals salt. I do 7 gallon water changes 1 x per week. The tank is a 58G with 15G sump. In the sump is Cheato (SP), return pumps, Coralife ss, and a powerhead for water movement. Parameters below.

Temp 80ish
PH 8.2
DKH 9.5
Calcium 390
No nitrates, ammonia, Nitrites detected.
SG 1.025 (refractometer)

 

[hangles]

depending if this is a new setup this is one of the things that new tanks go through. keep your phosphates down using a reactor or media pad. phosphates feed this algae so does light. you can blow this off your refug if you have a filter sock to catch it . keep you light cycle short for awhile till this goes away.
hope this helps!