pH keeps creeping up and can't keep chlorine level up

[JoannaB]

FC: 0
CC: 0-1
PH: 7.6 (was 7.4 yesterday after dose of pH-down)
TA: 80
CH 190 (maybe, sample turns pink and violet instead of red/blue--- so not sure i'm interpreting results correctly)
CYA 33

I spent all of last summer draining and refilling to get the CYA below 100. I added 240 oz of bleach 2 days ago. For the first 6 years after building the pool, the pH was always low and had to keep boosting. Since going TFP, it's the opposite. Always having to lower. If I don't add pH-Down every week it will creep up to 8.0. Advice?

 

[justinc]

240 ounces of 6% bleach would raise your chlorine level 7.2 ppm. Over 2 or 3 days that will all be consumed. You have to check and add chlorine daily. The reason you never had to keep lowering pH when you used tablets is because the tablets are very acidic so they added acid constantly (which is why you used to have to raise your pH). Try running your total alkalinity 10ppm lower and see if that does not slow your pH rise. You should/could also make sure you do not have excessive aeration of the water from spillovers, waterfalls, bubblers, etc. If you could turn those down or off etc. it would slow down your pH rise as well.

Since your chlorine has now hit zero, you may want to raise it back to normal and either run an overnight chlorine loss test or just go ahead and SLAM the pool until you meet criteria. When your free chlorine hits zero you don't have long before algae grows and you may not be able to see it...yet.

Also, can you give more info where these results came from? Your Taylor kit? How did you get 33 CYA (there is only markings for 30 or 40)? And what do you mean combined chlorine 0 or 1? How many drops to from pink to clear after adding the DPD 3 reagent?

 

[JoannaB]

I'll try lowering the TA a bit. I guess I thought that since the pool is getting little to no use, there would at least be a smidge of chlorine left after 2 days. The pool filter is on about 4 hours a day right now. We are still easing into summer here. The more I run the pool, the higher the pH gets; I guess that's because of the additional aeration. No water features. Yes, my results are from my Taylor test kit. The dot at the bottom of the test tube disappears just below the 30 mark, so I'm estimating it at about 33. I know it's not precise. For the combined chlorine the 10mL sample turns very pale pink after the 5 drops of R-003. Then it goes clear after 1 drop of R-0871. Maybe my math is off on that one. In past years I've had chlorine demand because we get a lot of worms and debris in the pool over the winter (even tho covered). I was hoping that wouldn't be the case this year since when I closed it last October it was about 75% fresh water from all the draining/refilling.

 

[justinc]

If you are using a 10mL sample and after 5 drops of R-0003 it only takes 1 drop to go back to clear, your combined chlorine is 0.5 and not anything to worry about.

If you are seeing your chlorine be consumed quickly, I would recommend performing the overnight chlorine loss test. If you fail that, you need to SLAM the pool. If you pass that, then your chlorine is being consumed by UV light and you may benefit from increasing CYA to 40-60.

Perform the Overnight FC Loss Test (OCLT)

The Overnight Chlorine Loss Test tells if the SLAM is finished or if you need to start a SLAM. This article says how to do the OCLT.

www.troublefreepool.com

SLAM - Shock Level and Maintain

We’ve all had to deal with a green pool. Clear algae from your pool with a SLAM! Read here to use shock level and maintain to clear your pool.

www.troublefreepool.com

 

[JoannaB]

Ok I'll give it a try. I used the TFP app to calculate the amount of bleach to bring it up to 4, but it only brought it to 1. Not sure what's going on. There is no sun on the pool at all. Water is crystal clear. Aggravating. Got it up to 3 with another 120 oz. That's the best I could do before bedtime. Will check it in the morning.

 

[justinc]

I'm going to guess if you're adding bleach and not hitting your targets either your math is wrong, your bleach is weak (old, outdated, left outside in heat or sunlight) or you have organics in the water from letting your chlorine drop so low. I would get ready to SLAM pending results of the overnight chlorine loss test.

 

[mmcwhorter]

I had a similar issue last year with TA at 90. My TA is around 68 now (per pool store print out and it matches my TFT-100 kit)....And the Ph is far more stable, less bounce. Never goes much above 7.8 whereas last year it would creep into the 8 range if I was not watching it. Less acid wasted. And my SWCG works fine to keep it around 7 PPM with CYA at 62.

 

[ajw22]

Your CYA is 40 if the dot disappears between 40 and 30. We round CYA up. That puts your FC target at 5-7 and minimum FC of 3. See FC/CYA Levels

If your FC dropped below 3 there is a good chance some algae took hold.

Needing to lower pH once a week in a plaster pool is common. You just never saw it before when using your tabs.

 

[JoannaB]

Checked just now. FC is at 2 after overnight test. Curious what it will be when I come home. probably zero again (cloudy cool day, no bathers). The bleach is from Walmart, their BASIC BLEACH. I just bought it but of course it could have been sitting on pallets in the sun. Who knows? I am very tempted to go buy a bucket of cal hypo. Buying the bleach in these quantities and frequency is getting cumbersome and I think a large quantity is going to be needed to try to break out of this.

 

[ajw22]

I do not understand why you are leaving your FC at 2 with CYA 40. Pour as much bleach as it takes to get your FC up to 7. And then try and keep it above 3 with daily chlorine additions.

 

[justinc]

Yes, OP you are running your chlorine too low. I would honestly SLAM the pool and then let it go down to 7 and try and maintain it there with daily additions.

You must feed your pool chlorine daily in amounts of 1-4 ppm at least during normal times. If you SLAM the pool and then routinely hold the chlorine around 7 afterwards and you are STILL dropping into the 1 and 2s still by the end of each day I would verify your CYA level is what you think it is.

You have a little wiggle room to use some Cal Hypo because your CH is 190... but don't go over 250 with the calcium.. Do the math in pool math to see how much each pound will add in terms of calcium hardness and stop once you get at or near 250

 

[ajw22]

I think Joanna can go uo to CH 350-400 without a problem. Depends what her fill water CH is.

 

[JoannaB]

I have been adding bleach constantly since I opened the pool. The only time I was able to get it up to 7 was when I added the last of my cal hypo. I'm out of bleach now. Will have to go get more. That's another issue. The amount of time and effort to get the quantity of bleach needed is becoming cumbersome. I'm no spring chicken! I will try to get it up to 7 with bleach before I go get more cal hypo. It's going to take a lot!

 

[ajw22]

Try and find Pool Essentials Chlorinating Liquid - Walmart.com or 10% chlorine in Home Depot or Lowes.

 

[JoannaB]

Our Home Depots and Lowes don't stock it for pickup OR delivery. Guess there isn't enough demand here. Walmart currently has some in stock online so I am ordering 10 jugs now. This isn't a good permanent solution though because they don't deliver and I have to pick it up at a Walmart that is inconveniently located. Will suck up my entire lunch hour today. ugh.

 

[ajw22]

Get a SWG and be done with the chlorine runs

 

[JoannaB]

I've been thinking of converting to SWG. I don't think it's too expensive but we have some taxes to pay first. Good news. Still had some FC in the pool when I got home. 1.5ppm. This is of course on a cloudy day with zero bathers. but that's better than I thought it would be. I got the 10% chlorinating liquid at Walmart today. Should I still SLAM or just bring it up to 4?

 

[justinc]

Since night will come in several hours for you in Oregon, let's raise it to 7 tonight right after darkness and then perform a FULL overnight chlorine loss test in the morning before any sunlight hits the pool... after you add.. test again 30 minutes later with the pump running and confirm you at least hit 7 or 8.

 

[JoannaB]

FC is 8 right now. We'll see what the morning brings. Thanks y'all

 

[JoannaB]

Little change. 7.5 this morning.