If the tanks are planted, how well are the plants growing? If your having algae problems chances are is that your actually missing a nutrient or metal in teh water column, leaving excess of others for the algae to grow off of. I would really suggest doing a full test for a planted tank, this will test your disolved oxygen, CO2, iron, ph, KH, GH, ammonia, nitrate, nitrite and I am sure there are a few other things that it will test as well.
On the 10 gallon, how often do you feed the DPs snails? (I found in my planted tank, that I could actually have the tank understocked and would get major algae blooms, and then once I fully stocked it, or overfed the tank, anything to bring up the ammonia being put into the water, the algae would go away)