My beautiful pool is now yuck

[vbharrington]

After a week of heavy rains and high temperatures, my beautiful pool is now cloudy and greenish. Last night we noticed that it was cloudy, so we added 4 gallons of bleach. This afternoon the pool looked worse! Here are our numbers:

TC - 0
TA - 100
PH 7.2
CYA <20

We have added additional water over the summer, so that may account for the CYA disappearing. I know that I need to shock the pool to get the algae under control, but while doing that, do we need to vacuum to waste or vacuum through the filter? We typically run our filter all the time, with backwashing when needed, so we will continue to do that. Any other advice would be greatly appreciated.

 

[woodyp]

With a sand filter it's easy enough just to backwash after vaccuming unless--------you have tons of green globs.

 

[Richard320]

Just vacuum to filter, You'll be backwashing a lot no matter what, so no point in wasting a bunch of water vacuuming to waste.

 

[domct203]

You will need to get your CYA to 30ppm and SLAM Process the pool.

If you don't mind the water loss you can vacuum to waste to get some of that algae out of the pool.

 

[vbharrington]

So - should I add the stuff and raise the CYA while I am slamming?

 

[Richard320]

So - should I add the stuff and raise the CYA while I am slamming?

Add enough CYA to get to 30ish. Use the sock method described in Pool School - Recommended Pool Chemicals

Then immediately take FC to 12. You don't need to wait for the CYA to dissolve. If the pool is green, the FC will be dropping before you finish adding the first dose. Brush everywhere, vacuum blindly if you have enough light. Retest and redose to 12 FC as often as possible but not more than every hour. It's all laid out in the SLAM Process article.

If you don't have any CYA, then target 10 FC until you can get to the store and get some. It'll be dark soon where you live, so you won't lose much FC to sunlight without the CYA. Get some bleach in there and kill that algae now.