adjust cya before or after shocking

[Kateyru]

sorry to report that I am back with algae problems. My test results at 6:30 pm today were FC= 6, CC = .5, pH = 7.4 and TA = 70. I've been adding CYA through stocking since the time I thought I had previous algae problem resolved. I was out of town for a week but tested on 5/4 and pH was 7.6. I starting dosing again with CYA on 5/5. I'd turned my SWG on again when I thought algae problem was taken care of but FC had stayed high 11, 10, then 9 on 5/5 so I turned SWG off. So,without SWG, FC was coming down and was at 6 today. But now I have algae again): What caused it? Is it because I forgot to test pH and keep it at 7.5-7.6? Should I have left SWG on? Trying to figure out where I went wrong. Also, do I need to raise pH before I shock again? I plan to use bleach to shock.
Thanks.

[aylad]

If you have algae again, it's because you either 1) let the chlorine get too low, or 2) never killed it off completely before allowing your chlorine to come back down. It has nothing to do with your pH. Your pH is fine where it is--you just need to raise your chlorine back up to shock level (best to do that with bleach instead of your SWCG). How high shock level is depends on your current CYA level. Do you have the test kit yet so you can test your CYA?

[Kateyru]

The chlorine has not been below 6 in at least a month so I guess the algae wasn't completely dead...tho I tested and went back and forth with the forum experts till we thought it was.
So, I will test CYA in the morning then check pool calculator to find amount of bleach needed to shock then test and keep at shock levels and test and on and on. Does that sound right?
Thanks.

[Watermom]

Yes. That is the correct plan. Don't test CYA too often, though, or you'll waste the reagents. Did you get the K-2006 kit yet?

[BigDave]

You ( and Watermom of course ) are right. Is the algae in the water or on the walls and floor? Brushing the pool will help get the chlorine to the algae stuck on pool surfaces.
So, the recipie is:
Bring your FC up to shock level for your CYA and keep it there as best as you can by testing and dosing as often as you can.
Shut off the SWCG and run the pump 24/7.
Backwash the filter when pressure climbs 8-10psi over clean pressure.
Brush the pool, especially where algae is visible.
When you have less than 1 ppm FC loss overnight and minimal CC (less than 0.5 if using the 10ml sample size), keep the FC at shock for one more day.
Please use the "Edit your signature" link in Watermom's sig to add your pool's particulars to your signature.

Be patient.
Don't worry, you'll get this under control.
Keep us up to date.

[PoolDoc]

I scanned through this thread, and could not find a reported CYA level . . . .

[BigDave]

On 04-15-2012 at 05:02 PM on page 7 of this thread OP posted CYA of 30, since then has been adding CYA in a stocking.

[Kateyru]

CYA = 40 this morning so according to "Best Guess" I need to shock at FC = 15 and stay there or above.
Dave, algae is mostly on the bottom and lower sides of pool. Thanks for recapping the steps.
I'll edit signature.
Thanks!

[BigDave]

Do you still have the dichlor? You can use that to move toward your shock level and your CYA goal but remember as CYA goes up so does your FC goal for shock and normal operation.
How much dichlor do you have on hand?
Is there still CYA in the stocking?
Do you bleach / Liquid chlorine on hand? How much?

[Kateyru]

No more dichlor on hand. There is still CYA in stocking but I have removed it from the pool. I don't have any bleach on hand so was heading to the store. Should I use dichlor or bleach? I haven't done a cost analysis. If I use dichlor, do I need to raise pH to 7.6 before I start?