Hello from Alabama

[summerswelter]

We have had our pool for about 6 years now and have had off and on issues with green algae. Up until 3 weeks ago, we have always been able to get control and have crystal clear water. We have shocked and shocked to no avail. Our pool used to be shaded and now we have full sun ( we cut the tree down).
I tested the water this morning using our K-2005 test kit

pool size is 20X40 lagoon style in ground vinyl liner

FC .5
TC 1
CC .5
PH 8
TA 150
CH 290
CYA 90
Temp is 85

We are just really stumped, we have put in algaecide, shocked the pool, backwashed the filter, added water. We have had several weeks now of high temps, high humidity and a fair amount of rain.

Any advice is appreciated.
Thanks

 

[Butterfly]

Welcome to the forum

Based on your test results, your pool is overstabilized - CYA is too high. I suggest that you do the water dance (series of drains/refills) to replace about 44% of your water to lower the CYA to about 50ppm.

After that, you can retest everything and see what else needs adjusting prior to starting the shock process.

 

[Bama Rambler]

Welcome to TFP fellow Bamian.

As BF said, your cya is too high and your FC is way too low.
Read pool school and pay attention to the chlorine/cya chart.

 

[Samantha_in_AL]

Howdy neighbor. When you shock your pool are you using bleach or a storebought "shock" product?

 

[summerswelter]

We have been using a store bought shock but after reading on this forum, we will be switching to bleach. AFter reading about BBB, we were only using one of the "B".

 

[Bama Rambler]

I only use one B I never have to add borax or baking soda. A little bleach every day and some acid once in a great while is all I ever need.

 

[linen]

Welcome to tfp, summerswelter

I am not using any of the B's right now since I have a swg (well I did top off my borates this year...but that was boric acid and 3 months ago)

 

[summerswelter]

Well it's been almost a month and just yesterday the water finally turned blue again!!! I am sure some bells were ringing somewhere. So here is the latest numbers:

FC-6
TC-3
PH 7.4
Alk 70
CA hardness 200
CYA 40

We have a 36000 gl
vinyl liner

Do you think we are finally stable now, it seems so but thought I would ask. Thank you for this site, it was a life saver in getting rid of the algae.

 

[linen]

Can you check your chlorine values? FC cannot be higher than TC.