Mustard Algae keeps returning

[Jason G]

We shocked the pool ,let it settle and then vacuumed it to waste. The pool was tested and everything was perfect,.The algae came bac within 2 weeks.It was recomended to me to treat it with copper sulphate which seem s to have killed the algae at this stage. The pool has changed to a more blue clour but is very cloudy. How can I fix this ? I also think my filter is not doing its job, it is 11 months old but has been spitting out this brown mustard for 6 months straight after you backwash it and start your filter again.

[mr_clean]

We shocked the pool ,let it settle and then vacuumed it to waste. The pool was tested and everything was perfect,.The algae came bac within 2 weeks.It was recomended to me to treat it with copper sulphate which seem s to have killed the algae at this stage. The pool has changed to a more blue clour but is very cloudy. How can I fix this ? I also think my filter is not doing its job, it is 11 months old but has been spitting out this brown mustard for 6 months straight after you backwash it and start your filter again.

you can start by letting us know your chemical readings,
FC-free chlorine, TC-total chlorine, CC-combined chlorine, PH-reading,
TA-total alkalinity, CYA-conditioner, CH-hardness levels.

The water has turned blue do to metals in water "copper" & adding a bottle of sequestering agent/metal remover will get rid of it. Remember to use a bottle every 6-months as a preventative as it will break down & can happen again.
You did not say the type of filter you have, If DE filter you need to clean it so all algae is out of it. If Sand filter you need to open & inspect for clumps/debris in sand, they do have chemicals to add which also help clean it.
What type of chlorine are you using? When using tabs your CYA level can get to high as tabs have it in them with chlorine. When CYA goes above 100 it makes chlorine less effective instead of protecting it from breaking down from the sun. The correct level for CYA is 60-80ppm & when high the way to lower it would be to drain some water & refill until it's in this range.
Also having no CYA can cause algae as chlorine would not be protected & you can buy some at a pool store & add.
When shocking pool you need to raise chlorine level above 20ppm & keep it there with filter running 24/7 until gone. You would need to check chlorine level 2-3 times a day & add liquide chlorine as needed to keep it boosted.
Make sure you are running filter long enough so you are turning over/filtering all of pool water. You never mentioned where you are so not sure how hot or cold it is outside. Here in So Cal pools are running 4hrs per day sense it's cold.