Black algae again

[Srh444]

Hi,

I have this black hair algae on my sand. It's green under white light as the photos indicate. There are strands floating from the coral. I have small clumps between a few rocks which are difficult to remove as they are too short. I've had this for a couple of months. I do a water change ever 8 days or so. The tank is 32 inches and 30g. It's been set up for nearly 2 years (Nov). I mainly have zoas as nothing else seems to survive. Corals I have purchased look great for about 6 weeks, then they start to decline and die. There are two clowns in the tank and a fire shrimp and a few cuc.
My parameters are:

SG 1.028
Temp 25/76
pH 8.2
Alkalinity 6
Phosphate 0.1
Calcium 480
Magnesium 1500
Nitrite 0
Nitrate 40
Ammonia 0.1
I know the Nitrate is on the high side and maybe the salinity. Any advice/help would be really appreciated.


Many thanks

 

[Gumbies R Us]

I would try to lower your salinity a little bit.
How is the lighting and flow in your tank?
Have you considered getting an ICP test done?

 

[Srh444]

I would try to lower your salinity a little bit.
How is the lighting and flow in your tank?
Have you considered getting an ICP test done?

Thanks for your reply.

OK will do that.

I have two double AI lights on the tank. I have the inlet / outlet flow, plus a gyre at one end. I've tried to direct the flow towards the sand but just blows everything.

I don't have a protein skimmer as the tank is small. Do you think it would help? Or should I leave it as it is?