Why is my sand bed getting reddish brown algae?


Reefing newb
Never had this problem before and its only my sand bed not my LR. I sifted my sand with my fish net and
my sand was back to its normal color but, a couple hours later reddish algae started showing up again on top os the sand

Kessil 350a Blue light 90% white light 30-40%
ammonia & nitrites 0
nitrates 0.00
ph 8.1


P.S. I know you guys will need more info just let me know what you need to solve this problem
I am guessing either diatoms or red slime.
Was it kind of a mat or dusty?
If you can get a pic, that would help.

What kind of water are you using?
RO water is the best as tap water can introduce impurities that can feed algae.
i use Ro/DI water.
photo-15 1.JPG
Looks like diatoms to me. Have you tested your RO water TDS? When was the last time you changed the filters on your RO system? It could be that they need changed and there are extra silicates in the water.
Diatoms react greatly to silica and then nutrients; your substrate will have abundant silica in it.

Try some GFH/GFO,it will help remove over abundant silica and reduce the diatoms via starvation.

The brown is their “silicon from silica” husk that they leave behind when they go into their planktonic stage.
I have a TDS meter on my filter and it says 25 going in and 0 coming out I also changed the filters about 2 months ago so there good.

I don't know what diatoms are so I will have to research that.

What is GFH/GFO? pkc

Thanks for the help guys
Diatoms are algae that are a very important part of the planktons phytoplankton and are closely related to protists and GFH/O is granulated ferric oxide-hydroxide,rowa phos is one.

Phosphate sponge will take out some silica as well.
Hey guys,
My phosphate coming out of my 5 stage ro/di filter is somewhere between .04 and .08 could that be contributing to my
reddish sand bed? Also what is a good way to clean it? I took out the reddish sand from the top rinsed it with tap water I was going to let it dry the rinse it with ro/di water and replace it. Will that get rid of the reddish stuff?

Also my Peppermint shrimp molted thats good right?
The shrimp molting is indeed a good sign... but the algae on your sand looks like diatoms to me. Taking the sand out and rinsing it (especially in tap water) is going to hinder more than help you.

Just let it runs it's course. They're ugly but not harmful.