Dark brown stained rocks.

[mbmikebray]

I have tried scrubbing the stains with a toothbrush but cannot remove the dark brown stains on the upper surfaces, the tank has been set up six months now - coroline algae is growing spots of green, red and blue, also pineapple sponges and lots of stringy sponge in different areas including the sump. Diatoms on the sand for a long time now and also on the rocks, however the rock surfaces are very dark brown almost like coroline algae which covers the entire surfaces but not the sand.
I have been reading on reef central and elsewhere for a while but cannot find much info about the dark brown stains..they only appear on the dry rock not the original live rock.
I decided to add some extra pink arrogonite sand a cple months ago and quickly had a severe diatom bloom on the sand which doesn't appear to be clearing at all, only a few pounds of extra sand on the surface at the sides of the tank.
I will post parameters a bit later with some pictures..
My apologies, l didn't intend to create such a long post. The dark brown stains are my main priority at the moment, thay didn't happen in my previous tank 75g which had very clean rock with colourful coroline algae, this tank 90g looks terrible at the moment.
Thank you for any info.
Will post extra details/pics later.

 

[mbmikebray]

Parameters

Parameters

Nitrate, Nitrite and Amonia all 0.
Mag 1320
Cal 430
All 8.3
Sg 1.024

Reefbreeders photon 48' led's.
2 × turbelle nanostream 6055 power heads.
95g with 30g sump.
Plenty of flow from the return into Dt. Danner 950 return pump.

My main concern is that the dark brown stains on the rocks seem like Coroline algae, embedded into the rock and could be permanent. Also a fussy short white fine hairy growth on top of some of the dark stained areas.
Any help would be appreciated.
Ty...

 

[mbmikebray]

Tried uploading pictures, will not upload at the moment - will try later!

 

[Ab129]

I was trying to upload pics last week with no luck and then I edited the image cropped it saved it and tried again and it uploaded.
Maybe coincidence but easy enough to give it a try.

 

[Icewing726]

Are you inadvertently feeding the diatoms silicates? Im battling them as well and while green algae is showing these guys keep surging and its probably due to me using tap water. I've also heard some salts can import silicates as well. If the growth is severe try a 3 day black out to cripple the diatoms. Then work on the areas that didn't die. I haven't tried this yet but its on my list if this continues. Apparently it works well. As for corals, the poster I read said its like a prolonged storm in ocean terms hiding the sun.

So consider that and consider using RO water.

 

[mbmikebray]

I have been using RODI from the beginning, the tds is zero - all the filters were replaced prior to to setting up the 90g during December last year.The diatoms are not excessive, they just seem to be constantly there mainly on the sand. It's the dark brown staining on the upper parts of the rocks which is my main concern, I can see coro.ine algae but it is overshadowed by the brown and fussy short whitish hairy growth also on the rocks....
I will try post I g pictures again.
Thank you for your reply....

 

[mbmikebray]

Tryi g to attach pictures...

 

[mbmikebray]

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