Excel will help control many types of algae. I use it in my heavily planted aquarium in conjunction with pressurized CO2. Are you EI dosing? If so, don't forget the VERY IMPORTATN 50% water change weekly. After the water change dose 1 capful of Excel per 10 gallons (as instructed on the bottle), then dialy dosage following instructions. I have corkscrew val in my aquarium and they are doing just fine with the excel.
I am doing 50% water changes twice a week. I have also modified my EI dosing by cuting potassium nitrate to 1/8 teaspoon, and cut out adding phosphates. I must have a lot of decaying plant mass because it doesn't go down at all unless I do a water change while the nitrates are being used up.
The diatoms if anything are getting worse rather then better I just want to correct what I can before it gets out of control. I added a lot of plants some died off one being myro I believe it was labed as foxtail at the fish shop. The only two plants that have noticible growth is the amazon sword and the ambulia.
Just did a 50% water changed nitrates were at 5ppm so dosed 1/8 potasium nitrate. Phosphates were around 2-3ppm so adding nothing. added 1/16 teasponn potassium sulfate and 3ml of seachem iron.
I might add some excel too drop checker is yellow ( surface agitation provided by an aquaclear 50 and spray bar is turned up a little on rena xp1)