Brown slime algae?!

[Aussiemarine]

Hey everyone

so I am battling the brown slime like algae and I’m struggling to figure out what it is and how to get rid of it.

It doesn’t look like diatoms or Dino’s - it kind of looks like cyano but just brown as it’s slime in some places but on the rocks looks less slimy.

parameters
Phos 0 (was up around 0.08 recently but using phosguard to remove that and any possible silicates)
Nitrate 10ppm
Calc 430ppm
Mag 1320ppm
Alk 8.2
PH 8.3-8.5
Salinity 1.025

My TDS is 0 for RO and for mixing ASW.

Im running an auto filter roller, 36w UV sterilizer, dual pump skimmer, refugium, ATS, carbon reactor, polyfilter (in case of metals) and phosguard (for phos/silicates)

What could it be possibly feeding off?
Lighting is 2x 2ft Orphek gen 1 lights plus three kessil a360s - tank is 5x3x2.

Corals and nems all seem fine but have had some polyp bail out from the euphylia recently...

 

[Oregon Grown Reef]

That looks like dinos, but hard to confirm without a microscope. Pick one up on Amazon for less than $100. Why are you trying to remove phosphates when they're at .08? That's a perfectly acceptable number. I wouldn't worry unless you're getting algae growth. Did you test the tank for silicates as well? Were you having issues with diatoms prior to adding the phosguard? Super low nutrients is exactly where dinos thrive.

 

[Oregon Grown Reef]

Remove the phosguard for now. Unless you have high phosphates, ie. .15 or higher, there's no reason to try to lower them.

 

[Aussiemarine]

Remove the phosguard for now. Unless you have high phosphates, ie. .15 or higher, there's no reason to try to lower them.

Was 0.41 at one stage so added 500g of phosguard and the lowest I got it to was 0.07-0.08 I just added a bit more which has brought it to 0 but will be retesting every other day to see.
I was getting insane GHA hence the reason to add phosguard. I am still getting loads of GHA even with the phosguard my fish can’t keep up, it’s covering the back wall.

I had diatoms when I first set the tank up 9 months ago but nothing since then it went away pretty quick.

Photo of the backwall

 

[Aussiemarine]

Yep looks like you are right - Dinos... I had Osteropsis before but UV wiped it out. Not sure if this is still osteropsis or a different type???

Video:

 

[Oregon Grown Reef]

Yep looks like you are right - Dinos... I had Osteropsis before but UV wiped it out. Not sure if this is still osteropsis or a different type???

Video:

That does appear to be ostreopsis. Start off by blowing off all of the rocks. Run a felt sock in your overflow so it catches most of it. Then use a hose to suck up the rest that you can. Drain it into the filter sock so you're not doing a water change, further lowering nutrients. You seem to have an issue with higher nutrients, which will help you in this case. With the UV sterilizer on the tank, just keep blowing off the rocks and scraping the glass to suspend it during the day. The UV sterilizer does wonders, as long as you have the correct glow going through it, if you put in just a little bit of effort. I went from a losing battle to victory with relative ease by doing this.

 

[thedon986]

Looks more like Large Cell Amphidinium to me. A closer, clearer photo would clear it up but it’s definitely presenting like Large Cell all over the sand. Possible little Small Cell guy running around in the bottom left. The tend to move faster. I have both in my aquarium, mostly LC.

 

[Aussiemarine]

Looks more like Large Cell Amphidinium to me. A closer, clearer photo would clear it up but it’s definitely presenting like Large Cell all over the sand. Possible little Small Cell guy running around in the bottom left. The tend to move faster. I have both in my aquarium, mostly LC.

Thanks yep it’s large cell - I have decided to live with it really and not do anything drastic at this stage. I have added a few more sand sifting clean up crew and they do a good job of clearing up a lot of it overnight and it doesn’t have time to cover too much during the day before they mow it again. Hopefully it will just not get out of control. A bit of red cyano is coming back on the sand so I’m going to let that grow out and cover what I can and hopefully that will pass too.