What Should I Do?

[discusfishies]

Hey guys, i have a few queastions.first of i set up my 55 gallon tank about 3 months ago and bought flora max as a substrate...WORST MISTSKE EVER!!Its looks terrible so i went to the store and bought some cheap black sand to put over top of it and it looked fine until little red chunks started comming up again recently ive been debating to slowly start taking out the flora max/ sand mix over the course of maybe a month? and after i get it all out ill get a few bags of eco complete and put it in to replace it.Is this a good idea? will it do any noticible harm to the benificial bacteria? My tanks fully cycled and the parameaters are Amonia:0 Nitrite:0 Nitrate: 5-10

My second queastion is my 55 gallon is facing towards a window so it gets a little bit of direct sunlight every now and then and recentyly ive been having major problems with algae! Im not sure what algae it is but above i attempted to post a picture of it. Im not exactly sure how to poste pictures on here yet. Its gotten alot worse since it was taken its taking over my dwarf sagg and my crypts and covering my amazon sword. Anyone have any ideas on what to do or even what it is? i heard putting in h2o2 into the water but after reading up on it, it sounds risky..thanks!!