Green pool despite lots of chemicals, working pump and new sand. HELP please !!

[esfcandm]

Water is passing through the filter and the pump. The only unusual things I notice are that when backwashing (a) dirty green water is visible at the top of the filter for a while, and (b) the sight glass stays completely clear, almost as if it was empty.

There's loads of chlorine, flocculent, and algicide in the pool, but it has turned green. The only change this year from last, other than the 2 points above, is that a friend of mine changed the sand in the filter.

Any ideas what I can do ? At present the pool is being filtered 24h a day... with no improvement in the water. In fact, it may be becoming even greener !!!

[Denniswiseman]

Let's have your numbers (CYA is very important) Use a pool store if you don't have a FAS/DPD kit
FC:
TC:
pH:
TA:
CH:
CYA:

[Teapot1]

You cant filter live algae, you must kill it first. That requires chlorine. How much depends on the water test as Dennis has already said.
We can help you as we have hundreds of others but please stop putting algaecide in your pool it doesnt work its a pool industry lie.

[heamicdan]

its not that the algea/silt has become too fine for the filter?

[Teapot1]

No its not.

[Paul Land]

This time of year (Heavy heat and rains) before our pool turns green like my neighbors does every year. I use 8oz. algicide with copper as algae preventative . Works every time.

[Teapot1]

Whilst copper algaecides work unlike the others care is needed as plaster/tiled/ pebble finishes can easily stain. Not so bad in plastic/vinyl pools but year after year the copper builds up and can cause issues. Better to examine why the water turns green and algae blooms, sometimes the chlorine is just too low for the CYA level, sometimes the phosphates are building up and phosphates are like caffeine for algae, a rich source of food.

[Denniswiseman]

I don't understand when some one asks for help and we say "let's have your numbers" they don't respond
Do they think there is a magic bullet that will cure all with no effort on there part

[Teapot1]

Yes frustrating isnt it Dennis, we take time out of our lives to help people and only a few come back to report or say thank you. We try to build a community to help others and then that can spread the word around but by and large all we get are selfish people who are after 1 off free advice. I would rather those people went to the pool store and got royally ripped off.