Green hair algae and Zoanthids not opening

[dougs280z]

My tank has been running for about 2 years and I just recently started getting a lot of green hair algae. It seems about the same time the hair algae came, the zoanthids and leather, and some mushrooms haven't been fully opening. The zoanthids really don't open at all. I've done a few small water changes recently along with removing some of the hair algae, but it didnt seem to help and came right back. I continue to test my water and can't find anything out of the ordinary. My tank is a 29 gallon. Parameters are:

Nitrate <5
Phosphate ~0
PH 8.2
Temp 79 F
Salin 1.024
Calcium 340

Nothing else major has changed. I have seen a lot more of the small white starfish showing up. They only seem to be on the coraline algae, but I don't know if they started thriving because something is off in my system. Any ideas? I read a few things that point to phosphate, but my test is showing 0.

 

[tthemadd1]

Could be old tank syndrome. How long does your tank stay cloudy if you stir up the sand?
Also if you have a lot of algae it could be a false phosphate reading because the algae is digesting the phosphates.

 

[tthemadd1]

Looking back at your old posts I see you have had this issue in the past? Top off water should be RO that should resolve things down the road

 

[dougs280z]

I always use RO water. I have had an issue in the past where the mushrooms wouldn't open. It lasted for a few weeks and then just went away. What exactly is old tank syndrome?

 

[tthemadd1]

Too much waste in the rocks and sandbed. I had my tank up for years and the system was overwhelmed and not able to nitrify quick enough. So the algaes took off.
Not scientific by any means but when I would disturb the sandbed the tank would be cloudy for hours with waste. That's why I mentioned it before.

 

[dougs280z]

I am still unable to solve this. I took a few of my rocks out with the most algae and scrubbed them off. I did find my temperature was higher than it was supposed to be, 83 instead of 79. My heater must have drifted some and I couldn't read my thermometer. I really thought that would have been my issue, but it's been 2 weeks since I found that problem and I think the algae has only gotten worse. I have some phosphate remover pads in my filter that didn't do anything either. Everything still checks out good as far as i know.

PH - 8.1
Nitrate ~0
Phosphate ~0

What else can I do? I've done some more frequent water changes and it doesn't seem to have helped anything.

 

[tthemadd1]

Margarita snails will do a good job munching it down. Also you phos is probably low because the algae is using it. Temp will only help so much. Also a sea hair is a beast on algae.

 

[tthemadd1]

Sea hare.