Combined Chlorine Issues

[hobie0]

I've been following the pool forum for 4 years and utilizing all the recommendations.

I have a 21,000 gallon plaster pool.

I have a Salt Water Chlorine Generator. But utilize bleach for my shocking. So, most of my pool maintence is done with just muriatic acid for ph and pressurizer for keeping alkalinity in check. For some reason once a year my phophate levels get extremely high. Greater than 3000 range. So I actually do use phosphate remover once a year.

I let my pool get low FC for about a month before I opened it when the pool water was above 50 degrees.

Although I still had crystal clear water.

My first readings were as follows 8 days ago:

FC: 3.0
TC: 6.5
PH: 8.1
TA: 180
CA: 200
CYA: 41
phosphates: >3000

I shocked the pool and adjusted with muriatic acid, calcium, including aerating. I also used phosphate remover and got these readings 3 days later.

FC: 20
TC: 23
PH: 7.0
TA: 80
CA: 280
CYA: 30
Phosphates: 500


After reading some other posts, I figured I was losing Cyanuric acid and getting ammonia, so I would up my shock level. So, I kept my shock level between 40-50 PPM FC for 4 days. I've let the chlorine come down a little now.

I just retested and have the following numbers:

FC: 20
TC: 22
PH: 7.2
TA: 82
CA: 280
CYA: 0

What should my next step be?
How high should I get my FC?
How long should I keep it there?
Should I add Cyanuric acid up to 60 ppm before or after I shock my pool.

Thank you in advance for your advice!!!

[aylad]

Hi, and welcome to the forum!! We're glad to see you here.

My first question is--what method are you using for your testing? The reason I ask is that it is almost impossible to go from a CYA of 30 to 0 with clear water. Normally when CYA breaks down into ammonia, it is because an owner has let the pool go into a thick, green swamp. In any event, there are ammonia tests, similar to those you use in aquariums, that you could use to check your ammonia levels.

You can go ahead and add your CYA, either by diluting and putting it into the skimmer slowly, breaking up clumps, and let it dissolve in your filter (don't backwash or retest for at least 4-5 days if you do it this way) or put it in an old knee hi or tube sock and hang it in front of a return to dissolve that way. Check the owner's manual for your SWG--most of them require a CYA of 60-80 ppm in order for the SWG to work as efficiently as possible. Since CYA dissolution is a gradual process, you can go ahead and shock the pool at the same time. For the time being, I would get it up to at least 15 ppm, but in a plaster pool it wouldn't hurt to take it up to 20 and hold it there until you have no chlorine loss overnight and your CC is less than .5. Of course, as your CYA level rises, so will the shock level (see the Best Guess chart at http://www.poolforum.com/pf2/showthread.php?t=365).

Janet

[hobie0]

Thanks for the Reply.

I use Lamotte ColorQ Pro 7 test kit. It has always been fairly accurate and I have never had any problems with the numbers. To test for FC above 10, I use the shot glass method. I use chlorine neutrilizing drops when testing pH and Alkalinity at high chlorine levels.

I already have my FC at 20. It was at 40 or more for 4 days already. So you think I should just keep it at 20 or higher for a longer period of time.

I think I will wait on adding the CYA until after my CC is eliminated.

Thanks!!

[aylad]

Try keeping it at 20 for another couple of days. There have been lots of reports this year of unusually high chlorine demand, as well as unusually high CC's. Don't know why this is suddenly happening, but the only thing you can do is keep hammering it with chlorine until you eventually break down the CCs. How much chlorine loss do you have overnight? (By that I mean testing after dusk, then again in the morning before the sun is on the pool). Anything swimming in it at night that you know of?

Janet

[hobie0]

I'm having a little chlorine loss at night. My chlorine levels have been so high, it is more of a guess at how much chlorine loss I am actually having. But, I am having some.

Hopefully, nothing is swimming in the pool at night. On second thought, maybe it would be fun to having something swimming in the pool overnight.

I do have a pool cover that I use. I have been leaving it partially open to let the chloramines air out at night.

Thanks for your help!!

[hobie0]

After reading some posts on the Lamotte Color Q Pro 7 and some issues with testing accuracy. I went ahead and purchased the Taylor K2006 Test Kit. I ordered online so I probably will not get it for a couple of days. I will keep my chlorine levels above 20 and then repost when I get the new test kit.

If I should be using higher chlorine levels, someone please let me know?