What’s my phosphate and what do I do about it?

[AquaAggie]

Ok so I have a bit of a green spot algae problem. It probably has to with lighting and fert imbalance but also read that low or high phosphate could contribute. So I got myself a test kit. I hate reading these things. What do you think my level is?  Secondly the instructions say that an established tank should be 0, but this goes against what I read about low phosphate and GSA. I think it looks darker in the picture than in person and would be one of the lowest 2 looking at it. It’s always hard to say, but definitely not high?

All pics are the same test, first one is with flash. 
 

Thanks.

[Markp2483]

I was having similar problems got the test kit and found I had zero phosphate levels even though I fertilize a couple times a week.  I’ve started adding a little seachem phosphorus and noticed a sharp reduction in gsa. Trying to keep the phosphate level in the 0.5 range. So far so good. 

[AquaAggie]

So then why does API say it should be 0 and what’s your take on my level?

[Markp2483]

Not sure, I’m assuming you have a planted tank. I’ve found some sources saying between 0.1 to 1 is ideal for a planted tank.  
 
Hard to say by looking at the photos but if you believe it looks low try adding a little phosphorus.  It should be safe and worst case is you’ll just end up doing a bunch of water changes to lower it again.