Pool Rookie w/ a Green Pool

[BigDave]

I'm still chuckling. How much Botox will I need to get the wrinkles out of my liner?

[lindley]

Alright so I've been working my tail off trying to figure this chemistry crap out and I'm getting it. I guess I shouldn't say crap as it is key. Thanks for the BOTOX...lol I mean Borax jokes btw. So after measuring my pool, and speaking with my buddy (Chemical Engineer) I am getting somewhere. The 6 gallons of bleach however did nothing. Unfortunately I had to go to liquid chlorine to get this under control but I want to use the BBB method so for now below are my findings and my numbers for my 15,000 gallon pool.

Chlorine: 15 PPM
TA: 150
PH: 7.8
Acid Demand: My tester only indicates referral to a chart which is telling me to add 3 pints Acid to my pool.
Bromine: 25 (why is this so high)

Pool is a little cloudy but how do I clear it up. I have added acid, liquid chlorine, but have yet to test today. Again, I want to do the BBB method but its 110 degrees here in AZ so the green algae was getting outta control. Now, all is blue.

What do I do now?

thanks
david

[PoolDoc]

1. Bromine test is IDENTICAL to chlorine test; there aren't any field tests that can tell the two apart. With a chlorine test result for 15 ppm -- if it were accurate -- you should show a bromine level of 2.2 x 15 or 33 ppm bromine. The fact that you show 25 ppm is just a measurement error. In actual fact, you probably have ZERO bromine in your pool.

Let me put it another way. If you have a pool with zero bromine, and an actual free chlorine level of exactly 1.0 ppm FC, and then test that pool for bromine, your test results will show 2.25 ppm bromine. Likewise, if you have a pool with zero chlorine, and an actual free bromine level of exactly 4.5 ppm FC, and then test that pool for chlorine, your test results will show 2 ppm chlorine.

Clear as mud?

Short version? Ignore the bromine test results!

2. Ignore the acid demand results, too. (At least for now!)

3. Household bleach is 8.25% sodium hypochlorite. "Liquid chlorine" -- if it's fresh -- is 10 - 16% sodium hypochlorite. Another name for 'liquid chlorine' is "commercial bleach".

4. You still need to measure your pool. It's probably not 15,000 gallons, either.

5. If everything is blue AND the chlorine is still high, BRUSH the pool. There are probably still pockets of algae, and you want to expose them to the chlorine while it remains high.

6. Run your pump 24/7. Do NOT backwash, till you see a 5 psi pressure increase above whatever the 'clean' pressure was. (This assumes that your gauge works properly).

7. Have you ordered a K2006? You're gonna need it. Actually, you need it now. Or rather, along with your pool dimensions, I really, really need to know what your actual alkalinity, calcium hardness, and especially, CYA levels are.
Test strips do NOT count!! Test strip accuracy is often bad, and CYA test results are normally horribly inaccurate.

[lindley]

1. Got it ignoring the Bromine test

2. Ignore Acid demand got it!

3. Commercial Bleach is the same as pool store liquid chlorine just in lesser concentrate

4. My pool dimensions are 30x14 8.5 ft in the deepest, 3.5 ft in the shallowest. I used a pool calculator online and they stated it was 17k so I just rounded down. What do you think?

5. Will brush the pool and redo my numbers right when I get home. I want my pool to sparkle!!!

6. i have only backwashed twice as my psi increased twice in a 72 hour period from 10 to 15. My sand filter is brand new and the gauge is working properly.

7. Yes I have, but It may be a week till i get it. I ordered from Amazon.

Thank you thank you thank you again!!!!

david

[PoolDoc]

17k is possible, though I'm surprised that that would constitute a diving pool. But don't round down. PF is 7, so 1 lb of stabilizer will increase your CYA level by 7 ppm and 1 lb of dichlor (55% chlorine) will add about 4 ppm of chlorine (0.55 x 7).

Then, backwash at 15 psi. It's good that it's increasing that quickly; that means the dead algae is not 'leaking' through the filter, which can happen.

Get a cheap OTO (yellow / red drops) test kit locally, and use it for now. Maintain chlorine levels in the dark yellow to orange region. If you reach 'orange' let the chlorine drop to dark yellow before adding more.

Brush. Vacuum.

Once the pool clears a bit, make sure the chlorine is high, and then turn the pump off for 24 hours. Much of the algae *may* settle to the bottom. If the algae settles, make sure the pool returns direct water AWAY from the bottom, turn the pump back on, and began vacuum algae off the bottom. 'Walk' bleach around the pool if the chlorine level starts to drop while the pump is off. If the algae does NOT settle, just turn the pump back on and continue filtering.

[lindley]

thank you Ben, but what is "PF" again?

-david

[PoolDoc]

PF = Pool Factor.

It's just a tool for calculating doses quickly, or in my head. It's the ratio of the weight of water in your pool to a pool with 1,000,000 lbs of water (~120,000 gallons).

A 120K gallon pool has a PF of 1, so a pound of added CYA will result in a 1 ppm increase in CYA levels