Need some advice... Tank not doing well.

[Oxymoron]

Long story short, I have been out of town working all winter and have had someone else looking after my tank for me.

After returning home my tank is in horrible shape..
Over the winter I had several losses including a mandarin goby, sixline wrasse and a pseudochromis that jumped to his death.

As far as corals I have lost a toadstool, and all of my zoos and mushrooms are in horrible shape.

Everything has a layer of green algae over everything and the sandbed looks like crap with spots of cyano.

I have performed 2 large water changes over the last week of 45 gallons each and have hand harvested as much of the crap i can get out, by constantly blowing it around and catching what I can with a net.

There is a fair bit of hair algae built up and the rocks still have all of they're coraline algae covered with green algae.

Any ideas where to start on this?
Ill be adding water parameters shortly and have another 45 gals mixed up in the basement. Going to be bringing carbon and phosphate remover online tomorrow.

Am I going in the right direction here or am I already too late?