red algea on sand

[nicetanknofish]

I have red algea growing on my sand bed, the red/purple algea seems to be spreading very quickly on my rocks in the last couple of weeks.
75g tank, 2 1/2 months old, 60lbs lr, 40 lbs ls, 2 fire fish, 1 lawnmower blenny, 1 cleaner shrimp, 1 peppermint, 10 nasarius snails, 10 hermit crabs, 1 star, 10% water changes once weekly.
Here are my readings S/G 25, Ammonia 0, Ph 8.2, Alk 4.5, trite 0, trate 0, Ca 400.
Please advise as to whether this is normal or how I might get rid of it.
Thanks

 

[taznut]

what do you have for water movement??? this is most likely your problem with the red slime algea...

 

[nicetanknofish]

I have 2 power heads, don't know what size (hubby knows) but I know they are bigger than we need and also the power head coming up from the filter that mainly moves the water on the top, the other 2 are more in the center and pointing toward each other.

 

[tomato clown]

Do a search here for red algea, I had that problem long ago, and sill do for now. It's mainly caused by topping off with tap water.
You can blow the algea away and catch it in a net, then simply toss it out.