I'm going to give credit to Tom Barr (plantbrain) since he has helped me big time in getting my planted tank from an algae infested jungle to a much better display with unmatched clarity.
First off those Hagen ladders are terrible at diffusing CO2. I had trouble getting 10-15 ppm in my 29 gallon with those units. I now run them into tom's venturi diffuser system and easily make 30 ppm+ CO2. If I used the kH-pH method of testing, my tank would have over 65 ppm of CO2!. Same Hagen system different diffusion method. CO2 is so high actuallly that the clear silicone tubing powering my airstone (for night time CO2 degassing) has been etched white. This never happened with the ladder system.
Next off, you need to get your nutrients much higher. In my 29 gallon 2.1 wpg tank with CO2 I dose the following 2x a week.
1/4 Tsp of Potassium Nitrate (KNO3)
1/16 Tsp of Mono Potassium Phosphate (KH2PO4)
1/16 Tsp of Potassium Sulfate (K2SO4)
5 mL of Seachem Flourish every second day
1 mL of Seachem Flourish Iron daily
Tank gets a 50% waterchange weekly. After a waterchange I dose the following in addition to the other fertilizers:
1/2 Teaspoon of Magnesium Sulfate (MgSO4 * 7H2O)
1/2 Teaspon of Calcuim Chloride (CaCl2)
Ever since I started this routine, my plants have gotten much much greener and algae has been dying back. My black beard algae so far has turned red and is being picked away at by my fish. I expect it to dissapear completely within a couple weeks. Contrary to popular consensus adding phosphates to your tank does not promote algae. Poor CO2 and fertilizer shortages do.
To buy these fertilizers go to
http://gregwatson.com He has excellent pricing and the dry fertilizers will last you over a year. To read up on Tom's Venturi CO2 design, go to
http://www.BarrReport.com His newsletter is very interesting though a bit on the complex side (I am saying this as a person who has a background in biology). I've learned a heck of a lot and would reccomend subscribing in a second. The venturi information though is in the free section under DIY Articles.
Good Luck