Shocking is no longer effective

[gdeboor]

Hi everyone. Just found this site and found it to be refreshing and enlightening. After mediocre success over the last 3 years with my pool I’m ready to leave the ‘dark side’ and give this a shot.
Here’s my situation:
My pool (see signature info) this year after encountering open season woes of green cloudiness has basically been crystal clear all summer up until about 2 weeks ago. Inadvertently ran out of tabs in the chlorinator and pool went from clear to cloudy in a matter of a few days. My normal method of checking chemical balance has been using check strips and an occasional trip to Leslies for a water analysis. According to the test strip I had zero FC and zero CYA. So I turned up the dial on the chlorinator and started shocking with a couple bags of CalHypo (Power Powder Plus) with little success. After a water sample test from Leslies they said FC was 2, CYA OK and to shock with 2 bags every 24 hrs. After 4 days and 8 bags of shock, the water again looks clear but FC reading according to strips each time is around zero.

After reading this forum it sounds like I have a looming algae issue as basically it is just eating my chlorine as FC is not rising. So I decided to go all in and ordered a TF100 test kit yesterday, but not arriving until mid next week. Understanding now the importance of CYA, I realize I need this number before I begin my shock process. For the heck of it I went to Leslie’s again last night and they said CYA was OK and at about 100 but ‘he was not quite sure’. How nice. My strips indicate zero. So basically I have wait until my TF100 comes as I have no idea what CYA is at.

My question to this forum. In the meantime (until mid next week) should I do anything? If my CYA really is 100 or more I expect I will be draining off part of the pool. If not, I will begin the bleach dump to try to sustain the shock level. However, if I have to drain I assume adding bleach now is just wasted effort.

Interested in thoughts. Thanks to all.

 

[Bama Rambler]

Since you know that your CYA is high and since Leslies has it at 100ppm I'd go ahead and drain a couple of feet of water a time or two while waiting on the kit to arrive. That way at least you'll be ahead of the game once the kit does arrive. Heck, you might even have the CYA to an acceptable range by the time the kit gets there.

 

[gdeboor]

Just to clarify. My strips say CYA is zero. Leslies says it's high. So I really don't know if it is high or low.
Thanks.

 

[Ohm_Boy]

If you've been using tabs for 3 years, as well as all this year, your CYA is doubtlessly sky-high, unless you've been doing a lot of water replacement. And with a cartridge filter, there is no backwashing, so there's been no water removal that way. Your CYA could be over 200 easy.

Here's my thinking - taking, as an example, a swim season of May through August = 123 days. If you only had a chlorine loss of 2ppm per day, you'd have needed 246ppm of chlorine. Using tabs, for every 10ppm FC they provide, they add 6ppm CYA, so you would add 246/10*6=147.6ppm CYA just over the season. So the low baseline is around 145 CYA.

Strip testing is useless. Or less than useless. You really could benefit from a good CYA test, but realize that most drops-based CYA tests only read to 100, so even if your CYA is 300, the test would show 100. Dilution would be needed to get a usable reading. Wal-Mart usually has an inexpensive 5 or 6 way test kit which will have a CYA test, but they may be hard to find this late in the season. Are there no other pool stores around?

Ordinarily, I'd suggest to go ahead and dump bleach in it, but in all honesty, in your case, I think I'd start replacing water.

 

[anonapersona]

You can dilute your water sample with distilled water and let Leslies retest. 2 parts distilled water and one part pool water might be a good start. Just to see if you get into a readable zone. Multiply the test value by 3 for approximate level in the pool.

 

[gdeboor]

Thanks for the replies. I finally got my TF100 test kit and was really surprised when I tested the CYA. Came out to about 20 or a little less. So the good news is I won't have to bring the FC up as high. I did go ahead and turn the chlorinator back on. This way I figure I can use the triclor to not only add some CYA but also help with the bleach shock which I plan to start tonight.