Help! Algae and ferts and levels!

[Puddle]

I am currently struggling with a hair algae problem - my PO4 was 0.25 to 0.5 and nitrates 10-20 ish. I have been using Nutrition + liquid from tropica for at least 6 months with no probs until now. My plants are also looking yellow/light and have seemed to stop growing? Anybody have any suggestions? I have a 180L tank with a few fish and I think enough plants, not rammed but full! Thanks

 

[Atl300zx]

How many watts of lighting and what type of lighting (Normal output floros, Compact Floros, etc)?

 

[Puddle]

I have a juwel multilix system with warm light and bright day lite tubes, both 30W.

 

[Jchillin]

Sounds like your not getting enough potassium, though I'm surprised that you are using Tropica and still getting hair algae. What is your current dosing regimen?

 

[Puddle]

I use 2X 5ml twice a week and about 7ml once a week on 3 separate doses. Went well on that for about 6 months, then got algae and tried reducing dose to 10ml/week which seemed to make it worse... I use the one with N and P, as I have few fish. I started using this as I got some cyano cos my N levels were very low and it really helped. The only other thing - the bottle is almost at its end - does this stuff go off?!!! Thought perhaps it was just old...
Thanks