Black Algae - adjust params

[northfish]

Need some guidance for dealing with an algae problem (black)

I know I need to clean my tank and remove anything with the algae on it, but I need some help with water params.

I have the following at the moment:

GH 9-10
KH 3-4
PH 8.5ish
NO2: less than .3mg/l
NH3: 0
CO2: .3ish

From the little I know I think my PH is high and water is too hard?

How can I go about getting these numbers within a better range.

I'm seeking the most natural way of adjusting my numbers.

Tank is about 2 years old and I think I live in an area with hard water (coffee machine needs regular cleaning) and PH must be added.

I have shut my lights off completely and just letting the natural daylight in the house into the tank for now. (I have blue LED's that are on at night).

Thanks everyone.

[Cliff]

from my experiance, keeping your nitrate (NO3) and phosphate (PO4) low and limited light is key to reducing any type of algae. I would test those levels and see were your tank is at right now

I would start there before even thinking about adjusting PH or hardness of the water

Do you have any plants in the tank ?

Dose you tank get any direct sunlight ?