Algae; not sure what to do

[Toomchfun]

7.5 FC (just added 96oz. to bring it to 10.5)
7.5 pH
100 TA
CYA ?

My pool has has had light green film on bottom for about two weeks. I think I let the FC go below 3 ppm for a couple of days and did not vacuum for 2 weeks. I brought the FC up to 10 as soon as I saw a light green area (two weeks ago) and ran my kreepy krawly. The water became cloudy. pH was at 8.0 to 8.2, I bought ph down from box store to get that back in order. I began running the vacuum 3 to 5 hours a day every day since last Thursday (6 hours on Saturday and Sunday). Raised FC to 10ppm on Friday and kept it there Saturday, it fell to 9.5 Saturday evening so I added the recommended amount on the pool calculator to bring it back to 10 ppm. I ran pump non-stop from Friday night to Sunday night. This afternoon (Monday) it was at 7.5 and a lot of green on the bottom. Kreepy Krawly began sticking to bottom today, I have never seen that, but it tends to miss some spots. It seems to be getting worse, not better. I'm at a loss as to what to do. Pool has been crystal clear since June by keeping ph, TA, FC and CYA at recommended levels. I'm thinking I need to get in daily and scrub bottom and sides.
A green cloud comes out of the return when pump is turned on. We have had a good amount of rain here in North Texas for a couple of weeks now. Does that contribute to the algae?

Any advice is much appreciated.

 

[linen]

We/you need to know the cya level to move forward with the shocking process that your pool needs.

 

[Toomchfun]

Thanks linen.
I'll check it in the morning. Water is relatively clear then.

 

[fast1971chevelle]

the reason it is getting worse not better is most likely because your not at shock level per your cya level thus letting the algae grow, please post up a full set of test results so we can help you get your pool sparkly clear again, also the ph test will show falsly high for fc >10 ppm i would let fc drop below 10 ppm so you can get a accurate reading on ph and lower it to around 7.2 prior to starting the shocking process...jmo.....Mike

 

[Toomchfun]

Updated test results: 12:15pm Tuesday

FC 8
CC > .5
pH 7.6
TA 100
CYA 40

CYA test - as I slowly add drops per instructions, the dot at the bottom is gone briefly at 60. Less than 1 second later it is visible. It disappears and stays gone at 40. Am I reading this correctly at 40?

 

[Bama Rambler]

I would say it's probably close to 50. But anywhere between 40 & 50 is fine to use.

 

[Toomchfun]

JasonLion posted that a pool should be at 7.2 to 7.4 pH before beginning the shock process. At 8 ppm FC can I trust my reading of 7.6 pH and begin to bring it down or should I let the FC drop more and take another pH reading?
With a CYA value of 50, the pool calculator says my shock level is 16ppm. A value of 60 the shock level is 18ppm. Is it ok to go high?
How long do I keep the pool at shock level?

 

[jblizzle]

pH test is affected once the FC > 10ppm. Lower you pH a bit before starting the shock process.
From the more aggressive Chlorine CYA Chart, shock level is 20ppm for a 50ppm CYA. You will not damage anything if you stay below the mustard shock level listed in the calculator (if that is what you are worried about). Just pick something between 16ppm and 20ppm as your target.

You stay at shock level until you pass the 3 test to stop: Shocking Your Pool

 

[Butterfly]

JasonLion posted that a pool should be at 7.2 to 7.4 pH before beginning the shock process. At 8 ppm FC can I trust my reading of 7.6 pH and begin to bring it down or should I let the FC drop more and take another pH reading?
The pH test is accurate with the FC below 10. So, yes, trust your test.

With a CYA value of 50, the pool calculator says my shock level is 16ppm. A value of 60 the shock level is 18ppm. Is it ok to go high?
Shock level for CYA of 50 is betweel 16 (Pool Calculator) and 20 (CYA/Chlorine Chart).

How long do I keep the pool at shock level?
Maintain the shock process until you meet the three criteria that show you are done. See red lines in my sig.

ETA:Jason is fast.

 

[duraleigh]

How long do I keep the pool at shock level?

That is the answer that eludes many, many newbies and that answer is the key to shocking correctly.

Read the article in Pool School on How to shock your pool and you will find you need to keep the FC high much longer than you think.

YOur pH result of 7.6 is close enough....I would shock without lowering the pH. It is also a valid reading you can trust.

Don't get your FC too high. That's why there are guidelines. 16ppm is fine but do not assume you can put in an unlimited amount of FC. Use 16 as your target if you like but retest often so you can replenish FC back to 16.

(Jason and Butterfly are BOTH fast)

 

[Toomchfun]

Thanks for all the feed back! A few more questions before I begin.

My AGP has no deck. How do folks brush while at shock level without getting in? Is it safe to enter?
How many minutes do I backflush and rinse my sand filter and how often during this process? Usually I go until the water is clear, is that the same for the shock process?
Should I run my Kreepy Krawly vacuum during this process?

 

[jblizzle]

Brush as well as you can ... actually getting in is not really a problem ... since you will not be putting your face in the water. We do not typically recommend getting in the water when FC is greater that shock level and you can not see the bottom (if you slipped under the water ... no one would be able to see you).

You should backwash when the filter pressure goes up 20-25% of your clean pressure. Then backwash until the water is clear. Do you have a multi-valve? If so some people alternate between backwash and rinse a few times.

There should not be a problem with running the vacuum during the shock process.

 

[Toomchfun]

I'm not sure what a multi-valve is. The top of the filter has the options with a notch at each one. I turn the pump off, push down on the lever and turn to the desired option, then turn the pump back on.

 

[jblizzle]

That is a multi-valve. Some filters only have a push/pull valve with only the backwash option.

 

[Toomchfun]

This is my valve[attachment=0:3fylp8fn]untitled.bmp[/attachment:3fylp8fn]

 

[jblizzle]

If it has a rinse/clean option, then alternating between it and backwash a couple times will clean things out a little better.

 

[xiaobulu]

May I please ask a related question here? Does it mean it is not safe to put your face in the water when FC is greater than shock level? I did that multiple times while shocking my pool.

I yet to clean my lights. Shall I let FC come down and then do that? Thank you!

Brush as well as you can ... actually getting in is not really a problem ... since you will not be putting your face in the water. We do not typically recommend getting in the water when FC is greater that shock level and you can not see the bottom (if you slipped under the water ... no one would be able to see you).

You should backwash when the filter pressure goes up 20-25% of your clean pressure. Then backwash until the water is clear. Do you have a multi-valve? If so some people alternate between backwash and rinse a few times.

There should not be a problem with running the vacuum during the shock process.

 

[jblizzle]

May I please ask a related question here? Does it mean it is not safe to put your face in the water when FC is greater than shock level? I did that multiple times while shocking my pool.

I yet to clean my lights. Shall I let FC come down and then do that? Thank you!

Ugh ... I never should have said anything. It is not so much the high FC that is a problem ... but if you have higher CC since you are in the shock process, they could be more irritating. Or there could be other things in the water that required the shock process.

Easiest to just say ... safe when FC is below shock level, CC is not more than 0.5ppm, and you can see the bottom ... Because that implies that you have completed the shock process.

 

[xiaobulu]

Alright. Thanks!

Ugh ... I never should have said anything. It is not so much the high FC that is a problem ... but if you have higher CC since you are in the shock process, they could be more irritating. Or there could be other things in the water that required the shock process.

Easiest to just say ... safe when FC is below shock level, CC is not more than 0.5ppm, and you can see the bottom ... Because that implies that you have completed the shock process.

 

[Toomchfun]

Tuesday evening:
FC 8 ppm
Cleaned skimmer basket
Cleaned lower basket
Backflush and rinse
brushed sides and bottom of pool
Raised FC to 18.5 ppm

Wednesday 7:00am
FC 18 ppm
water cloudy

Wednesday 12:00 noon
FC 13 ppm
Raised FC to 18

Wednesday 6:00 pm
FC 13 ppm

7:00pm
FC 20.5 ppm
Water looks better
Ran vacuum 7:00 pm to 10:15pm

Pump running non-stop