Not sure what this is, cyano maybe?

[ficertyn]

I'm really not sure what's going on with my tank.

I went out of town for a few weeks. Most everything is automated. When I returned, the sandbed looked like the attached photo.

After the water change today, my params were:

Nitrate: 28.7 (this appears to be spiking, but the red stuff was there before)
Phosphate: .21 (minor increase over last week)
Alk: 6.8 (dropping for some reason)

This is in a 15g aio setup. Two clowns, a branching gsp, ricordea mushroom and a small zoa are the inhabitants, aside from a cleanup crew.

Any ideas of what I'm looking at here, and how to deal with it?

Edit: Of course my photo isn't attaching...

https://imgur.com/a/is-this-lPFdSNp

 

[BanditMan15]

It is so very hard to keep water parameters in check on such a small tank and you be gone weeks at time. Now you can get away with it in something 200g. You just won't have a lot of fluctuations. I see a lot of people do wc every week if not daily on smaller setups. Not saying it can't be done bc we all have seen georgious small setups.
What Biofilter you using?
What size WC ?
You need to do at least 50 to 60% wc to help bring those numbers down. That would be the natural way, keep chemicals out of it. Again all this is imo

 

[Mr. Mojo Rising]

There are no pics attached. If your nitrates are almost 30 after the water change, they must have been higher before, phosphate also high, I would do a couple more water changes. I always come home to an algae problem after leaving the auto feeder on a couple of weeks.

 

[ficertyn]

It is so very hard to keep water parameters in check on such a small tank and you be gone weeks at time. Now you can get away with it in something 200g. You just won't have a lot of fluctuations. I see a lot of people do wc every week if not daily on smaller setups. Not saying it can't be done bc we all have seen georgious small setups.
What Biofilter you using?
What size WC ?
You need to do at least 50 to 60% wc to help bring those numbers down. That would be the natural way, keep chemicals out of it. Again all this is imo

I've got some ceramic balls in the back that came with the setup (it's the helloreef deal).

Water change was 10%. I can easily bump that to 20%. It's hard to get to 50-60% without draining most of the water out of the display.

 

[ficertyn]

There are no pics attached. If your nitrates are almost 30 after the water change, they must have been higher before, phosphate also high, I would do a couple more water changes. I always come home to an algae problem after leaving the auto feeder on a couple of weeks.

Yeah, for whatever reason when I attach the pics, they don't stick, and when I try to include it in the body it says "something went wrong".

I added a link to the pic on imgur since that seems to be working ok for me.