Pre-opening algae treatment

[Water_man]

One of my fellow snow-belt pool owners hasn't listened to my warning about the need to perform a spring pre-opening partial drain because snow and rain replenishment raises the water level above the cover, and the result is a mildly green pool. The issue was discussed here.
I want to help the poor guy before the pool pro comes and opens the pool and starts the pump. Also, pool season here doesn't start until the end of May, so it may take some time before they actually open. Here's what I have in mind:
First we're pumping water out so that the cover, which is infested with leaves and other organic products, is no longer touching the water. Then we are going to shock to 20 PPM (I have no idea what's his CYA level, so I'm assuming 50) and use two submerged pumps for circulation. Is anything wrong with this plan, until the pool is opened? What else can be done?

 

[frustratedpoolmom]

I see nothing wrong with using pumps for circulation...however, I would put the pumps in first and let them circulate for several hours, then test the water. I wouldn't advise shocking without knowing what the CYA level is, or the PH level as well....I mean if his CYA is over 100, 20 FC won't do much...

And if he has very low CYA, 20 could be too much....

 

[Water_man]

Well, this was a classic case of improvisation under pressure. Thew weren't ideal conditions.
A test kit wasn't available - the owner just ordered one, and CYA could be estimated at around 50 because of previous habitual use of trichlor. The cover not only had a "jungle" on it, but also a green paste of algae. Something had to be done quick before this pool becomes a swamp. A stitch in time saves nine, but you gotta do the single stitch.

 

[frustratedpoolmom]

If he used trichlor it could easily be higher than 50.

What? We get no pics?

 

[Water_man]

Thank you, frustratedpoolmom, for following this thread.
I didn’t think about pics when it happened, so I don’t have good “before.”
After 18 hours of circulation, the water is clear and the bottom is visible. Water clarity isn’t bad, although not perfect. We stopped the “green devil” in time!
Also, since the bleach was spread through the mesh cover, the algae gunk on top is gone!
Test results: FC: 13.5 CC: 0.5 pH > 8.
Plan of action until this pool is opened: Get muriatic acid and lower pH, keep FC above
10 (test every 3 days) increase circulation by adding a third submersed pump. Can’t test for CYA yet because of shortage of reagent. Any comments?

 

[frustratedpoolmom]

Yes. High FC makes the PH read a false-high. Don't adjust ph when FC is above 10, wait until the FC drops below 10 to retest the ph it may be at a normal level.

 

[Water_man]

Yes. High FC makes the PH read a false-high. Don't adjust ph when FC is above 10, wait until the FC drops below 10 to retest the ph it may be at a normal level.

This is a good one, thank you for the reminder. How much does high FC affect pH? More than one pH unit?

 

[frustratedpoolmom]

Yes. High FC makes the PH read a false-high. Don't adjust ph when FC is above 10, wait until the FC drops below 10 to retest the ph it may be at a normal level.

This is a good one, thank you for the reminder. How much does high FC affect pH? More than one pH unit?

That I don't know...I just repeat what they tell me. Seriously, there is this explanation, but I'm on a need to know basis and all I need to know is don't test and/or adjust PH if FC is above 10.