Super low pH (and other problems)

Hello,

I've been working on getting my just opened 30,000 gal pool to go from black to blue (current status - blue green and cloudy).

My pH is reading REALLY low. It doesn't even put any color on my multi-test pool strips (which start at 6.8).
I have two sets of homebrewing strips I tried out in the pool - 0-14 & 4.8-5.8. The 0-14 strips put the pH roughly in between 4 & 6, and it looks like the 4.8-5.8 strips are reading 5.0. (These strips are a few years old - what's their shelf life?)

So, after reading this site, I dumped in two boxes of borax and got no reading this morning (mutli-test 6.8 min only, I was in a hurry) on the pH again.

Could my pH really be that low?

If so, what should I do? More borax? Bite the bullet and pay for Soda Ash? Lye?

Thanks,
Matt

(I've also dumped probably over 50 lbs of Cholrine shock in over the last couple days, and still can't hold a non-zero free chlorine reading - could the pH mess up the strips?)

1. Get a good testkit -- the HTH 6-way is available locally at some Walmarts; otherwise buy a cheapie OTO kit. Regardless, order a K-2006 (info page in my sig)

2. A pH READING of 6.8, on your kit does NOT mean "6.8 exactly"; it means "6.8 OR BELOW". You'll get the reading with pH 5.0, 6.0 and 6.8.

3. Use borax, 4 boxes at a time, added slowly to the skimmer every 4 hours. Drop back to 2 boxes at the first sign of pH increase. You can also buy "Washing Soda" -- soda ash -- at most Walmarts. Borax is preferable, but soda ash is a stronger base and you should use it if you clean out the store's borax before you get your pH up.

4. We have seen many, many cases of biodegradation of CYA (stabilizer) to ammonia this year. The leftover ammonia creates a HUGE chlorine demand. If you have an ammonia strip, you can get an estimate of how far you still have to go, but we've seen pools take 120 ppm of chlorine to clear the ammonia. (The only other option is drain and refill, which is usually NOT an option for inground liner pools.) Try to use an unstabilized chlorine for clean up. On your pool, 7 gallons of PLAIN 6% household bleach would be about 15 ppm of chlorine. That's a reasonable nightly dose for you. Test your chlorine in the AM; when you hold chlorine over night, you are getting close to being done.

Got the HTH 6-way, 12 boxes of Borax and 20 Gallons of clorox.

Ran the HTH pH and cholrine tests, and, surprise, surprise, the pool held 2 ppm chlorine all day (after the strip read 0 this morning, I put about 2 lbs of shock in, so I'm thinking the strips were wrong all along), and the pH was so low I could barely tell the difference between the pH solution and the chlorine solution (it was that yellow). Added 4 boxes of borax, waited a few hours, and retested - pH had moved to almost 6.8, maybe a bit lower. I just added two more boxes of borax, and 4 gals of bleach (I didn't add the whole 7 because I wasn't starting from 0).

I feel like the pool is on its way to balance - thank you so much!

Post full HTH test results: chlorine, pH, alk, calcium, stabilizer!

Quote:

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Originally Posted by wildweasel

so I'm thinking the strips were wrong all along

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And that, folks, is why we call them 'guess-strips!'

pH = 6.8 (this has actually been making progress - the mixture color now matches the 6.8 color on the kit, instead of being way yellower)
Cl = 2 ppm
TA = 80 ppm
Hardness = 110 ppm
CYA = 95 ppm

Quote:

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Originally Posted by PoolDoc

Post full HTH test results: chlorine, pH, alk, calcium, stabilizer!

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Good deal.

But, with a CYA=95, you need to raise your chlorine level to AT LEAST 5 ppm, and if there's the slightest bit of algae, to 10 or 15 ppm. You'll need the K-2006 to measure those levels accurately, but you can approximate with the OTO test, where orange-y yellow = ~15 ppm, and orange = ~ 30 ppm

After firing in 6-7 gals of bleach in every night for almost a week, my chlorine, which was holding at 2-3 ppm (but never getting above that) dropped to 0.5 today. Water is blue (with a hint of green) and cloudy. My k2006c arrives tomorrow. Should I have upped the bleach dosage while waiting?

Yes. As Ben stated in post #7 above, with a CYA reading of 95, you needed to keep your chlorine at LEAST 5ppm. Since yours was 2-3ppm, that wasn't high enough to keep algae at bay and it sounds like you may have an impending algae bloom. So, now you need to shock the pool up to about 20ppm (per the Best Guess Chlorine Chart in my signature below).

Run a full set of numbers when your kit arrives tomorrow and post them. You'll want to do this before you shock the pool, especially the pH test because it won't be accurate at a chlorine level of 20ppm.

I got the kit, started the new chlorine test, and couldn't get the water to turn pink - I check with the old HTH kit, and got 0 total chlorine and a pH of 6.8. (strangely enough, the pool was noticably clearer though)

So I added 4 boxes of borax, 9 gals of chlorine (per The Pool Calculator) and waited 5 hours.
Then I got the following k2006c results:

FC: 3 ppm
CC: 1.5 ppm
CYA: 110 ppm (slightly more than 100?)
pH: 7.2
Alk: 80 ppm
Cal: 100 ppm (I do have a plaster pool)

So more chlorine? 8 gals by the calculator (3 -> 20 ppm)?
More borax too?

If you add 2 scoops of powder and it does not turn pink, then you have no chlorine.

Yes to adding more bleach and keep an eye on the pH. You are ok at 7.2 but don't want it lower.

Can you dilute a water sample (1 part pool water, 1 part distilled water) and then run the CYA test with that mixture and multiply the result by 2. Then, post with that result.

@ 9 AM:

FC: 12 ppm
CC: 1.0 ppm
pH: 7.2


@ 7 PM (and a trip to the store for some distilled water)

FC: 7.5 ppm
CC: 0.5 ppm
pH: 7.2
CYA: 110 ppm

I can see the bottom, though the pool is still just a bit cloudy.
Gonna go dump in a box of borax and 4 1.4 gal jugs of bleach.

Pool History Entry Form for wildweasel
Pool History Results for wildweasel

Quote:

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Originally Posted by PoolDoc

Pool History Entry Form for wildweasel
Pool History Results for wildweasel

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I like those forms, especially as often as I'm now checking the pool.

It looks great - not quite crystal, but I can see the bottom easily.

When I do the CC portion of the chlorine test, and add the 5 drops, it's clear (no change at first) and after it sits for 20-30 sec it gets a real slight pink tint, that one drop of the other solution clears right up. Does this mean I've gotten rid of the the CC, or that there's somewhere between 0-0.5 left?

Thanks,
Matt

Don't worry about low CC residuals. The DPD test is not perfect. I'm not sure what some of those residuals are, but I've seen them on pools I was running, when there was NO problem with the water -- crystal clear, no irritation, etc. Remember the goal is not perfect numbers, but a great pool -- and they are NOT the same thing.

Pool looks good, not perfect, but close.

So I can back off from shock to maintenance chlorine levels?

Give it a try.