HELP - High TA ph CH

[eddman]

Opened pool up major algae. 0 TC, pH - 7.8, TA - 170. CYA <10.

So i looked here and did a super shock with about 8 gals of 6% bleach then ran filter for 18 hours, retested FC about 5 still green tinge so added 16oz calcium hypo - 73%. Ran filter 18 hours more.

Algae hasd disappeared but now I am getting the following readings:
TC < 1
pH 7.9
TA 220
CH 360
CYA < 5

Additionally, the pol is cloudy and some sort of clearish scum floating on the top.

Advise?

Pool:

20x40
39,000 g
Sand Filter
Polaris 360

[AnnaK]

Welcome to the Pool Forum!

I have some questions for you:
What kind of pool do you have? Vinyl liner? Concrete/gunite?
How do you test? Pool store? Strips? Test kit? If you use a test kit, what kind?


According to Ben's Best Guess Chart you need to maintain FC = 10 ppm at the very low level of stabilizer you currently have. You cannot fix a green pool with one or two doses of chlorine. It's a process and takes some time and patience.

If you have a vinyl liner you don't need the calcium so just use bleach as your chlorine source and never mind the cal-hypo.

Please take a look at the Pool Calculator. It will tell you how much bleach to add to maintain the FC at 10 ppm. Keep the pump running, brush your pool, backwash/rinse the filter when the pressure goes 8 or so points above normal. You are done shocking when an overnight chlorine test shows a loss of 1 ppm FC or less.

Keep filtering, brushing, and adding chlorine, and get some stabilizer in there—if your current test results are correct the chlorine you add is being eaten up by sunlight and not doing much good. Use the Pool Calculator to tell you how much CYA you need to get to 50 ppm, then add half that amount to start with.

Let's clean the algae up first, then we can drop the pH (and the TA). The cloudiness of the water indicates the algae are not yet all gone.

[eddman]

My bad..

It is a concrete/gunite pool, 39,000 gallon, pacfab/pentair 30"sand filter, 1hp hayward pump, polaris 360.

The algae and green is gone..there is no green tint and I have been feeding bleach to keep TC up about 5 but it just drops everyday. The cloudiness appears to be suspended particles.

For testing I use a drop and titrate kit, just purchased, yea a cheaper hth kit but it does do TC, pH, TA, CH, and CYA.

[polyvue]

My bad..

It is a concrete/gunite pool, 39,000 gallon, pacfab/pentair 30"sand filter, 1hp hayward pump, polaris 360.

The algae and green is gone..there is no green tint and I have been feeding bleach to keep TC up about 5 but it just drops everyday. The cloudiness appears to be suspended particles.

For testing I use a drop and titrate kit, just purchased, yea a cheaper hth kit but it does do TC, pH, TA, CH, and CYA.

Sounds like progress. Of course, it's tricky to know how much chlorine you're shocking with if your test kit only measures up to 5 PPM... and with no measurable CYA the sun may be burning it off faster than you can add it. That's why AnnaK's advice about shocking until an overnight chlorine test shows LESS than a 1 PPM drop is so vital.

The overnight test is really two measurements - the first test of chlorine should be taken after the sun sets and the second, before the sun hits the pool in the morning. Don't add chemicals, especially chlorine, between the tests. If you start off at 5 PPM chlorine and the morning's test shows 3 PPM chlorine, the algae is still in the process of being purged.

You might want to supplement your test kit at some point with a FAS/DPD Chlorine test. Its measurements are more precise, easier to read and have a wider range. It's available from any number of on-line web sites -- the best $25 you'll spend this year.

(I wish I could get a commission for the number of times I promote this test.)

[CarlD]

"(I wish I could get a commission for the number of times I promote this test.)"

YOU do? We mods could all retire if that were true!

Seriously, you need to increase your CYA levels to at least 30 ppm, and decrease your pH and maintain your FC.

You can do it by adding acid and stabilizer and maintaining your daily bleach additions.

Particularly with stabilizer, you want to go slowly. If you follow the recommendations on the container, you'll go 'way too high too fast. Add about 1/3 to 1/2 of what you think you need. You can put it in an old sock or, better, panty hose and hang it so it doesn't land on the floor of the pool. It will take 2 to 7 days to dissolve. Patience is the key to adding CYA (stabilizer). If after that it's not high enough, add more.

Adding acid doesn't take so much time, but, again, don't try to do it all at once so you don't overshoot. Still, your chlorine will work better when pH is in the 7.2-7.5 range than where it is now.

When your pH is lower, measure your T/A again and you'll see it's lower. Do not use anymore Cal-Hypo at this point.

Temporarily, as an alternative, you can safely use either di-chlor powder or Tri-chlor tabs as both add CYA and acid, lowering your pH. If you test regularly, you can use these until you hit your target pH and CYA levels, then stop using them.

[aylad]

Just wanted to add one other comment--remember that the chlorine kills algae, but your filter is what removes the dead stuff from the pool. If you're still having overnight chlorine loss, you need to get the chlorine back up there to 1 0 and keep it there, as Anna pointed out. Keep the pump and filter running, backwashing as needed, until all the cloudiness is gone.

Hang in there, it will clear up, but the key is to maintain that 10 ppm chlorine level until it does.

Janet