Cloudiness is often dead algae, which has to be filtered out. But if you don't have enough chlorine (shock level), it will re-bloom.
So, you added algaecide (which one?) last night, and today there's a change. I'd hazard a guess that the algaecide contributed. The algaecide likely killed some algae. And now, you see dead algae in the form of cloudies. Sounds about normal to me. At this point you're going to have to keep filtering and I'd say raise to shock level till it clears out.
Chlorine is really the best algaecide though, and while it's in the seasonal pools information to go ahead and use algaecide, you do not have to. If you chlorinate properly, you really do not need it.
I'd suggest adding the FAS-DPD reagents to your 6-way HTH test kit, and also the cyanuric acid reagent. Then you'll be able to shock the pool properly, filter out the dead stuff and move forward.
Since you spent so much time dealing with iron, maybe draining isn't the answer. You can do it like everyone else with larger pools, and shock it, maintain shock level, and filter till it's clear. If you can find one of the 800gph or 1000gph filter/pumps that will help as well. You can use the Walmart brand filters (the paper/media in these looks like it has little dots) which will catch a lot more of the fine particles than the standard or OEM cartridges (that look like a dryer sheet). They do plug up faster, but it's worth it to get the water cleared out.
I'm confused over your CYA level, being that you didn't say you added any CYA, nor did you say you used trichlor or dichlor to shock or set up. So, if you haven't added CYA or used powdered or solid chlorine, you don't have any in the water. It'd be a good idea to add that right away, to about 40ppm.