Fixing chlorine levels

[Cantabridgian]

Argh! I've had a 3,000 gallon Endless Pool for about 6 years and I never had any trouble balancing the water until I recently had to leave the pool alone for a month (the pool has separation anxiety, apparently). Ever since then, it's been nothing but trouble. I've gotten most of the levels under control, but the chlorine simply won't behave. I get high combined and low free no matter what I do. Just now I got .12 free and .45 combined. I decided to add the amount given using the TFP calculator, and that was 1/4 cup of 8.25% bleach.

Can someone tell me the right amount of bleach to burn off the combined and leave me with some free chlorine?

 

[linen]

Welcome to tfp, Cantabridgian

Can someone tell me the right amount of bleach to burn off the combined and leave me with some free chlorine?

I am sorry, but that is impossible to tell you, since we don't know how much sanitizing and oxidizing your pool needs.

Did the FC go to 0 when?:

I recently had to leave the pool alone for a month

If so, you likely have algae and need the SLAM process. See: http://www.troublefreepool.com/pool-school/shocking_your_pool

Is this endless pool inside or out?
Is it covered?
Do you keep it at a raised temp, and if yes, what?

Please post a full set of test results. See: http://www.troublefreepool.com/pool-school/read_before_you_post

 

[jblizzle]

Welcome to TFP!!!

I agree with what linen said.

What are you using to get your test results?
If the FC will not remain, the answer is always add more chlorine and follow the SLAM Process.

 

[pwrstrk]

Another vote for SLAMIng !!

 

[Cantabridgian]

I love you guys! How did I not find that SLAMing page? To answer your questions, I'm using a ColorQ photometer with brand new reagents. It is an indoor pool, so no CYA.

Chlorine readings are FC: .12, CC: .45. I had a pH of 7.6, TA of 116 (Endless Pool recommends 80-120), and calcium hardness of 141 (recommended range 175-250). Before I posted, I corrected the pH and calcium, and added what I now know is an inadequate amount of chlorine. Temperature is 82 degrees. I will test and start SLAMing tomorrow morning at 7 a.m., and I can retest and dose starting at about 4 p.m.

I did have some algae, but it disappeared a week ago. I was adding chlorine and brushing the pool every day. Can someone let me know how to interpret the shock level chart when there is no CYA?

And if I haven't taxed your patience past the breaking point, what can I do to protect the pool water the next time I have to be away? These Endless Pools seem to need daily attention, which is not a problem when I'm home. I swim every day and add chlorine according to the formula of 1 cup per bather-hour, i.e., if I swim for 30 minutes, I add a half cup, and so forth. Until this recent disaster, all the other levels stayed right on target except the pH which needed minor tweaking about once a week. Even the saturation index was perfect.

 

[jblizzle]

I am not really sure what SLAM level is with 0 CYA. Are you sure it is 0? Never used any Trichlor tablets or Dichlor powder?

If it is truly 0, you may not want to go above 5ppm (guess? )

We usually recommend 30ppm of CYA for indoor pools. Not for protection from the sun, but for the buffering ... making the FC much less aggressive.

We don't think very highly of the digital testers. No way to know if they are correct and they have been proven to be pretty bad at some of the tests. Do a search of the site and see.

 

[Cantabridgian]

Thank you, Jason.

Yes, the Endless Pool people are clear that CYA should not be used. On the other hand, I never asked why, and I will.
I switched to the photometer after having consistent problems reading the color changes. I'm not entirely color blind, but I obviously have some deficits. When I started using the ColorQ, I checked against the Taylor K-2006, having a friend read the color changes, and I found it was spot-on.

I've read pool school from start to finish, and I only have one more question about SLAMing. Assuming I calculate shock level at 5 ppm, it would be okay to swim. But will it interfere with the SLAMing process if I do?

 

[jblizzle]

With 0 CYA, getting in at a 5ppm might not be a good idea, that is a much higher active chlorine level than the slam levels with CYA. In fact 5ppm may be high than you want to go. You would find the pool much less harsh with the use of a low CYA level. There is no good reason not to use it. Most of the pool industry is clueless about the FC/CYA relationship.

So you have never used any solid chlorine? Only liquid?

 

[Cantabridgian]

That's right. I've followed the EP instructions pretty closely, which means using small amounts of chlorine bleach. It never occurred to me that CYA would serve a function other than protection from sunlight degradation. CYA is recommended in outdoor Endless Pools, so it obviously isn't a contraindicated. Can you get me started on how to introduce it? I haven't SLAMed yet since I was waiting til the weekend when I'll have time to check obsessively. Keep in mind that I'm only dealing with 3,000 gallons!

How often must I clean/replace the filter cartridge? My filter pressure gauge never goes above the level shown when you put a brand new cartridge in. No real surprise there, since nothing falls into an indoor pool. I replaced mine while beating back the algae on the theory that algae must have been happily growing in there. But in the absence of an algae outbreak, would I be correct in guessing that the cartridge can be left alone longer? How long?

 

[jblizzle]

Use PoolMath to determine how much stabilizer to add to get to about 20-30ppm. I think CYA is one of the tests that your tester is not good at. Just get it dissolving in a sock in the skimmer if you have one.

Then SLAM with a FC level of 10ppm, which I think also maxes out your tester.

Clean the filter when the pressure rises 20-25% over the clean pressure.