Drained 3/4, re-filled and ready to re-start

[markmac]

As in my previous post, my CYA was extremely high. Last night I drained 3/4 of the water, and overnight re-filled it. It's municipal water and oddly, my pool is now greenish.

Here are my measurements.

FC 10
CC 0.5
PH - not sure, it was purple. I assumed it was high as before, and added 24 drops before it came down into the normal range. Does that sound right? Could it be that high with 3/4 municipal water?
TA 130
CH 340
CYA 70 (gives an idea how high. I could not really measure, but if 3/4 is new water and its still 70, it must have been really high.

So, any suggestions on a plan of attack from here?

 

[duraleigh]

Other than the greenish cast, is your pool water looking pretty clear?

 

[markmac]

yep. Not as clear as when I started, but pretty clear. can see the bottom drain clearly at +8 feet.

 

[markmac]

given the greenish tint, I assume I start by shocking?

 

[duraleigh]

Hold on that for a little bit. can you test for iron by any chance? Has the pool been tested for iron at any time?

Have you added acid to get your pH down into the mid to lower 7's?

 

[markmac]

I'm still not sure on the PH reading. Does it sound right that it could be so far off that I had to add 24 drops in the k-2006 kit? It turned purple, and I was not sure which way to go. given it was high (7.8) before I started, I figured it was high and starte working down.

Is there any chance of it being too low?

As for Iron, before the 3/4 draining I had it tested and it was 0.

If I understand correctly, you suggest gettign the PH in order before shocking?

 

[Butterfly]

Is the green a clear green or cloudy green?

When I refilled my pool w/municipal water, as soon as I added chlorine it turned the clear green tint color. Metals. Sequesterant fixed that.

I see your FC is 10. Was the water clear until you added chlorine?

 

[Butterfly]

Did/Can you test the pH on your fill water?

Regardless, yes, the pH needs to be figured out/adjusted first.

 

[markmac]

I've not added anything yet. I was attempting to shock the pool before the drain, but with a CYA so high, I was not getting anywhere.

Just checked the municipal tap water and its 8.0. Should I start with assuming an 8.0-8.5 for the pool? I donlt really want to add the 4 gallons of acid the tables show given my 24 drop count when tesiting the PH.

 

[JasonLion]

One way or another you need to get the PH into range before shocking. That may or may not require a lot of acid, mostly depending on the TA level of your fill water. Fill water with high TA will take a lot of acid to bring down the PH. But if the fill water TA is low, it will be very easy to lower PH.

 

[markmac]

from pre and post TA test, it has not changed 130-140.

I've justed added 32oz of acid, so I'll re-check the PH after 4 hours with the pump running.

 

[duraleigh]

so I'll re-check the PH after 4 hours with the pump running.

The pH comes down rather quickly. Pump running continuously, you would be safe to check and re-add every hour, if not every half-hour depending on your circulation.

Keep adding in the 32 oz increments until it tests in the mid to low 7's.

 

[duraleigh]

There may not be a requirement to shock. As your pH gets into the 7's continue to lower it right on down to 7.0 - 7.2. There is a good chance the greenish tint will disappear once your pH is down.

Credit due here to chem geek and Jasonlion who have been discussing this post (and others similar) with me.

However, if that works, is there anyway I could get full credit?

Of course, if it fails, please refer all legal correspondence to the two folks mentioned above!!

 

[markmac]

thanks. I had to step out for 4 hours anyway. After runnign the DE filter with new DE, its turning blue fairly quickly. Glad I didn;t shock immediatley now.

Just checked PH and its already down to 7.6 with just teh original 32oz dose of acid. Is there a reason to bring it down to 7.0-7.2? Will that help other values?

 

[Bama Rambler]

The only reason I'd bring it down now is to help lower the TA a little. It's a little high for anything but a tablet chlorinated pool.

 

[markmac]

well, running the DE filter and adjusting the PH has made it crytal clear and blue.

My ph is down to 7.2, and my FC is at 7 currently. When the sun goes down, I'm going to tweak the FC to 12 per the CYA table given a 70 CYA. I'll do the overnight check to see if I'm losing anything.

Thanks for all the advice. I'm glad I waited for some feedback befoe just jumping to shocking the pool when it had the green tint to it this morning.

 

[duraleigh]

Regardless of the sequence, I don't think the DE had much to do with clearing your pool. I believe it was iron precipitate turning back to solution.

I would suggest you keep your pH down low ALL the time 7.2 - 7.4 and introduce some sequestrant into your pool to keep the metal from precipitating back out. Jack's Magic "Purple Stuff" is one of the best.