Now I am starting to get this stringy type algea stuff on the glass of the tank and on the leaves of the plants...
Will an oto eat this? If not, how can I get rid of it?
You can remove most of it by hand as it does not really attatch to things well, but rather gets entangled in them. As Cavan said you need a good carbon source, wether it be Flourish excel or DIY CO2 or a combination of the two. DIY co2 is very easy to make using an old 2 Liter soda bottle. If you search DIY CO2 on this forum you should be able to find all the info you'll need.
I've been using Flourish Excel about 3 times a week. Should I use it more. I just don't want to add too much... I aslo have Flourite as a substrate, and use Flourish comp, trace and iron...
I have an Oto, will that eat any of it?
For your 10 gallon tank dose 1 ml every day as is stating in the instructions. You don't really have to worry too much about overdosing excel. Every time you do a big water change dose 5 ml. That should start to clear things up. If not, then up your daily dosage to 2 ml. Also, try and manually remove as much as you can to give your tank a jump start in getting rid of it.