You should do everything in your power to move your tank. Direct sunlight from the bay window will cause wild temperature fluctuations throughout the day which can be extremely stressful to your newt. It will also probably lead to higher average temperatures, another source of stress which may prove fatal.
As to the algae, ditch the treatments, most don't work and the ones that do can be toxic if used incorrectly. In this case, prevention is the best method of keeping algae out of the tank.
Algae is alive. For it to thrive it needs the same thing every living creature does: food. Food for algae includes nitrogenous compounds that come from newt wastes and food/living matter that decays, light and a few other nutrients. The easiest way to stop algae from growing out of control is to reduce the food sources.
Sunlight provides huge amounts of energy to algae, so tanks should be arranged so that sun doesn't strike them. It is virtually guaranteed that any tank that gets direct sunlight will have algae. For your fish tanks shutting off aquarium lights unless fish are being observed can also be useful. Keep light to a minimum. Newts don't need it and either do fish generally. Use aquarium lights only if you are there to observe.
The other source of food can be removed by feeding only what your animal can eat immediately. Remove all uneaten food as soon as possible. A turkey baster works wonders for this. Remove all newt poop as soon as you notice it. Both of these easy tasks will limit the amount of nutrients available for algae to feed on. Perform regular weekly water changes. These will make the water better for your newt by reducing the buildup of toxic chemicals and it will also remove potential algae food.
By limiting the two sources of algae food with the methods I mentioned above you can help ensure that your tank has very little to no algae. Any additional algae can be left to grow, because as said above, it can be rather beneficial by removing some chemicals before they can hit toxic levels. Algae can also easily be scraped off with a new toothbrush or a washed razor blade. Most razor blades are coated with oils to prevent rusting before they are sold.
Let me strongly urge you a second time; move your tank to a different part of the house so the newt doesn't have to deal with the many problems of direct sunlight.