Treat water or drain?

[jimk0512]

Here are the numbers for my 10,000 gallon above ground vinyl pool, using Walmart/HTH 6 way test kit:

TC: 3.0
pH: 7.2
TA: 200
CYA: 100+ (could not see black dot with water level at 100)

Checked these numbers with an AquaCheck test strip, and got:

FC: 3.0
pH: 7.2
TA: 180 to 240
CYA: 100 to 150

The pool water is green.

I have read several postings, and don't think most people have this much stabilizer. I believe these numbers are real, and are caused by chemicals from local pool store.

Should I pour in gallons of bleach and try to treat this apparent algae? Or drain out most of the water, and refill with city drinking water?

[duraleigh]

Hmmm, that's sort of a tough call. A WAG on bleach costs would probably be $40-$60 and you'd still have that really high CYA as a lingering problem.

If 5000 gal of city water was reasonably priced, I'd drain 1/2 of it. A 2/3 drain would be even better. You'll still have to use quite a bit of bleach (to get rid of the algae/green water) but most likely not as much and you'll have gotten your CYA manageable.

[waterbear]

I have to agreee with Duraleigh. If you get your CYA level down the pool will be much more managable in terms of treating the algae and also in normal chlorination. Shoot for a CYA level in the 30-50 ppm range if you can.

[hulla]

Another vote for draining half or more.

[mbar]

me too - if possible drain at least half, it will be much easier to clear up the water and keep it that way.

[jimk0512]

Thanks for your advice!

[jd.pool]

Hi All,
I have the same exact problem...
Can I ask though if it is ok to drain 1/2 the pool with a vinyl liner?
I thought I read somewhere that was bad for the liner.

Also...if you do drain 1/2 of pool is it best to shock remaining water before adding new water (to kill algae)?

Thanks.
Joe

[kalan]

Hi, I remember a thread before the crash that dealt with a guy that had a weekend home with a pool. Since he was only there on the weekend he was running a high cya pool and basically shocking before he went home on Sunday. The chlorine lasted all week and he was good to go when he got there on friday. I also remember there was some thought that this maybe an ok way to run pools. Add chlorine once a week and keep it high enough so it doesn't go below the minimum on the best guess chart. Just a thought.
Ken

[duraleigh]

Joe,

AS long as you only drain about half your pool, the liner will be fine. As you drain, observe for any wrinkling or movement of the liner that might not come out when the water refills. If you observe something you don't like, stop at that point just to be safe.

I would suggest you refill completely and then shock. Your pump probably won't circulate once you drain below the skimmers. Additionally, you'll only have to shock once instead of twice

[jd.pool]

Thanks Dave. Good point. I'll try that.
Thanks again.

[jimk0512]

Just a note, to let folks know how things ended up with my green pool (with high CYA of 100). I talked with the City about the water. They asked me not to drain half the pool, because of the drought, and the water restrictions they are currently enforcing. Since I was going to be out of town for a week, I decided to let the algae go and see if it would consume the CYA. When I came back on 7/25, my numbers were:

TC: 0.0
pH: 7.8
TA: 210
CYA: 100

The CYA didn't drop, although the pool was really green the entire week, according to my kids.

I went to the local Sam's, and bought as much bleach as would fit in my car. I started pouring it in, until I reached 20 to 25 ppm using an OTO kit with 4 parts distilled to 1 part pool water. And then I kept it there, three times a day, and brushed once per day. After using 11 jugs of chlorine bleach (6%, 1.4 gallon each), the pool water is clear. First time I've seen the bottom in I don't know how long (years, probably, since I used to use Bacquisil, so the pool was always a bit milky). My only issue is that I still have 7 jugs of bleach left, and my wife wants it out of the kitchen ...

My numbers this morning were:

TC: 20.0
pH: 7.0
TA: 180
CYA: 100

Currently, I'm using dry acid to try and bring the TA down a bit, which is why the pH is lower.

I'm planning to let the TC drop by itself to around 10.0, and then keep it there.

Thanks for the good information on this forum. Sorry I didn't take your advice and drain half the pool. I'm thinking about draining early next year, when I open the pool, if the CYA is still at 100. Unless we are still under water restrictions ...

[duraleigh]

Jim,

Thanks for the update. You did what you had to do and reached a successful conclusion. I partucularly like that you recognize the need to maintain the 10ppm Cl level. I doubt you'll have another issue all Summer.

Read Ben's Sticky "Lowering Alk...." in that forum. Dry acid is not very successful. His method is. Happy Swimming.