algae problem in a 3.5G Tank ...need some help, please

Hi everyone,

My name's Alessandro and I'm from Italy. It's one year I came back to the hobby after many many years. It's long time by now that I'm attending the forum and picking a lot of precious informations up. But now I'm stucking with an algae problem. Below you find the aquascape details:

Tank Size: 13 x 8.5 x 8 in

Volume : 3,7 US gallons

Substrate: 1 1/2 in potting soil + 1in gravel

Plants:Rotala rotundifolia, Pogostemon helferi, Hemianthus callitrichoides, Staurogyne sp, Micranthemum umbrosum, Hygrophila polysperma.

Fish/Animals 5 Neon Tetra, 3 Hyphessobrycon flammeus, 1 Otocinclus Affinis, 3 Red Sherry Shrimps, 1 Neritina natalensis, 1 Apple Snail.

Lighting: 1 CFL 25wts 6500k (mounted vertically 11 inches over the substrate)

Filtration: Aquaclear Mini with some ceramics and sponge

Fertilization: EI 1/2 dosing + DIY Co2

Decorative Materials:rocks

The tank was set up in October 2012. Every week I change 40% of water and clean the glasses.

My problem is that I always have Green Dust algaes and some Green Spot algae on glasses and on leaves of the plants (mainly on Staurogyne sp). I never was able to get rid with this algae problem. For months I tried to find the right equilibrium between light, Co2 and fertilizers.

The light is on for 10 hours with siesta regime: 5on-4off-5on. I use this regime to low the level of Co2 after the night because I cannot switch off at night the injection.

Since I have a canister filter, I inject the Co2 directly into the inlet such that the impeller breaks up the CO2, allowing it to dissolve in the filter chamber. To check the level of Co2 I use the Drop Checker (4dh Solution). It is bright yellow but fish and shrimps are all fine and active with no strange behavior. The plants all grow fine with (apparently) no deficiencies. Just the Hemianthus does not grow very fast. The tank is only 30% plant stocked.

Please find the following questions:

1) Is the tank fish overstocked?
2) Is the light to much?
3) Is the EI dosing to low?
4) any other comment and remarks?

Many thanks in advance for your attention and help.