I think this one is going to be pretty tough. What are the parameters for the water currently in the tank? I wouldnt make any moves until that’s answered. Don’t put any water in until you test.
I’d do a slow drip for like 6 hours a day over multiple days until the tank is filled. Then if you want aesthetics you can clean the glass of algae with a scrapper
This looks like an awesomely healthy tank to me. Even if you think it’s unsightly, your remaining (and future, fingers crossed) shrimp are probably loving the “grime” and overgrowth. As others have said, I’d just slowly add new water to the tank and keep an eye on your parameters. If you can get your parameters stable, I’d leave the rest alone. Maybe scrape algae just in the front of the tank & do a light “vacuuming” along the bottom with a turkey baster.
You can just scrape the glass and fix the water Params otherwise leave it. I found the hard way trying to over-clean a tank tends to lead to bigger issues
Winter_Economics2809 
I think this one is going to be pretty tough. What are the parameters for the water currently in the tank? I wouldnt make any moves until that’s answered. Don’t put any water in until you test.
I’d do a slow drip for like 6 hours a day over multiple days until the tank is filled. Then if you want aesthetics you can clean the glass of algae with a scrapper
Hold up, clean it?
Clean what? The water spots?
There’s no algae on the glass, the plants look fine. The moss on the rock is a little intense, but would look nice with water.
What am I missing here?
EDIT: Wait, that little bit of algae on the little rock on the right? Is that what we’re talking about?
This looks like an awesomely healthy tank to me. Even if you think it’s unsightly, your remaining (and future, fingers crossed) shrimp are probably loving the “grime” and overgrowth. As others have said, I’d just slowly add new water to the tank and keep an eye on your parameters. If you can get your parameters stable, I’d leave the rest alone. Maybe scrape algae just in the front of the tank & do a light “vacuuming” along the bottom with a turkey baster.
You can just scrape the glass and fix the water Params otherwise leave it. I found the hard way trying to over-clean a tank tends to lead to bigger issues