Filter the water constantly. Backwash or clean the filters frequently as dead algae is being trapped in the filter.
Test the water using your test kit. Don't just keep adding chemicals. Balance your pH first by adding muriatic acid if needed. Let it run at least an hour after adding the acid then add more chlorine shock if needed. If the water is stil green my bet is that you will find that the chlorine level is still low.

Chlorine level needs to be raised to shock level and maintained there until there is no more combined chlorine in the water and the Chlorine level holds over night. Shock level is dependent on the stabilizer (CYA) level. This is the only way to kill the Algae.

We had a pool that looked like that - we had been using Baquacil for a long time when we started to get an algae bloom.

I'm still not convinced that the pool store didn't give us something with chlorine in it while we were still on Baquacil. It went from some algae to dark green overnight.

We ended up switching from Baquacil to chlorine -- that was the only way to get rid of it.

Here pics of set up

Pipes

Filter

More

How is this for pressure

Still need help

Looks like too much Mutator acid to me. :)

In all seriousness, if this is a Chlorine pool: Get a good test kit like the K2006. Test CYA. Forget all the other chemicals and get a bunch of bleach. Get the CL up to 20PPM (Won't know where you really need to be without a CYA reading). Hold it there for a few days and it'll clear up. Then worry about ALK, PH and CYA.

If it is Baquacil then you are in trouble. Google Baquacil to Chlorine conversions and good luck.