Help with green pool and numbers

[JenLM]

Hi! My husband pulled back the pool cover this week and found a couple of hundred tadpoles who had taken up residence in the pool, so we decided now would be a GREAT time to go ahead and open the pool. ;)

Anyways, I have forgotten nearly everything I learned last year so could you help me figure out the best plan of attack? My pool stats are in my siggy.

The pool is a little on the green side, but the debris was fairly settled. We jumped the gun and added bleach already. I also gave it a good brushing. Our filter is running as well.

Here are my readings tonight, 3 hours after adding about 10 gallons of 6% bleach.
CYA- 70 (It was high at the end of the season last year.)
FC- 5.5 ppm
ph- 7 (could be a little lower?)
TA 70

So should I stop adding bleach and address the ph first?

TIA!

[Watermom]

You can work on pH and add bleach at the same time with no problem. Add a box of 20 Mule Team Borax (laundry aisle at Walmart) slowly to the skimmer while the pump is running, breaking up any clumps. Retest pH after a couple of hours and redose as needed until you get the pH between 7.4-7.6 (although anyplace 7.2-7.8 is ok).

Keep your chlorine at shock level while you are trying to clear up the green. Shock level is based upon your CYA reading. Take a look at the Best Guess Chlorine Chart in my signature below. Run your pump 24/7 while you are working to clear the pool. Keep an eye on your filter pressure and backwash when you see an 8-10psi rise over clean filter pressure.

[aylad]

Just a comment to add to Watermom's advice....the shock level for a CYA of 70 is actually 20 ppm, and you won't be able to get an accurate pH number with your chlorine that high, unless you're using a K-2006 kit. If that's the case, then you can work on the pH and shocking together. If you're using the regular OTO kit like you get at WalMart, then you'll get falsely high pH readings when your chlorine is over about 10 ppm. So....if that's the case, I would add your Borax, make sure you're over pH 7.0, (because pH below 7.0 can damage your liner) and THEN go ahead and shock your pool.

Janet

[Watermom]

Good catch, Jan. Actually, I think the pH test is accurate with chlorine up to 15 when measured with the K-2006 kit and up to only 5 if using the OTO if I am remembering correctly. But, you are right -- since her CYA is high and thus her shock level will be high, she should raise pH above 7.0 before shocking.

[JenLM]

Thank you! I do have the Taylor kit so I am able to monitor ph. My ph is up to 7.2 so I am going to add about 75 oz of borax according to the pool calculator? We'll keep shocking and vacuuming and hopefully we'll be in good shape soon. =)

Is there anything I can do for CYA?

[aylad]

Your two options for CYA are to just compensate with higher chlorine levels (which might actually decrease your daily chlorine loss, depending on how much sun your pool gets), or to drain/refill a little water to lower it. My personal advice would be to just compensate with chlorine for now (see the best guess chart linked in my sig for more info), don't use any stabilized form of chlorine, and let it lower itself due to backwashes and splashout. By mid summer you'll probably be down to the 50-ish range, where we advise people to keep it, anyway.

I intentionally keep mine in the 80-90 range because that's where I lose the least amount of chlorine to the sun, and it allows me to not have to dose my pool everyday, but my pool is in full sun in 90-110 degree temps during the summer.