Lime green pool after using Ecoklean Maintain

Hello, I live in NJ and have owned my Doughboy above ground pool (32X16 10,000 gallons)since I bought the house in 92. Every year I get it going without too much trouble. Sand (Hayward) filter.

This year I opened a little late, water was brown, shocked and used algaecide, had it where it was getting better, could see the bottom, all coming along nicely.

A few years back I had a cloudy water issue and a pool store sold me Ecoklean Maintain(cellulose I believe). Since then I have read a few threads here already regarding the product. After installing the product (as per instructions on bag..two scoops), my backwash was a bright green, and the water may have been getting better. At one point though, I added a little extra Ecoklean and let the pump run for over 24hrs, woke up on morning and it was bright green..just like the back wash was prior.

Long story short, the chemicals were right on but I could not get rid of the green. Used two clarifier brands thinking I had a bad batch, no luck.

Seeing as how the bright green corresponded with the Ecoklean use, I assumed I had gummed up the filter head mechanism and I was recirculating the water not filtering. I bough an entire upper section for the Hayward filter..the entire mechanism. It has been running a few days now, no help, I have brushed, vacuumed shocked again etc.

I am now thinking to replace the sand itself. After finding the forum I have read experts advise against using cellulose products. Too late for me I guess.

My Chlorine is at 10, Alk. around 90-100, ph around 7.5 CyA around 100.

When I back wash it is not the lime green it was with the Ecoklean in use.

Any advice appreciated.