If you poured untreated tap water into you filter media the chlorine will most likely have killed the majority of your bb and crashed the cycle.
If this is the case do 20/30% daily waterchanges until the tank cycles again. Your going to need a test kit.
We've conversed on a different thread about this issue, so here things to fill in the gap:
1. OP is on well water, so no chlorine/chloramine
2. Fish were moved from 30gal to 75gal with inadequate bb from original tank....so, probably new tank syndrome.
3. He's been treating tank with Melafix, chemical clarifier and bottled bacteria.
OP we've discussed in length about your issue and I gave you my recommendation. I still strongly believe that you have a bacterial bloom and not an algae bloom. With all the unnecessary chemicals you've added to the tank, you've brewed yourself a decent chemical cocktail. You need to stop adding all this crap, including the Stress Coat, and start purging that nasty water. 20%-30% daily w/c, while may work, it will take too long. 50% every other day will make a significant impact without altering the chemistry too much that will affect your fish.
I know there's a lot of information and opinions for you to make sense of right now, but if you hang out here long enough, you'll be able to put together what will work best for you. Experience only comes with time and learning from mistakes made. Good luck