Chlorine Block?????

I am so frustrated. My husband is ready to fill in the pool. This "chlorine block" has happened 3 years in a row. We always open to a dark green pool and it takes a while for us to get it clear. It is now sparkling clear but very little free chlorine level.

I have 24.000 gallon vinyl pool with a DE filter.

FREE CHLORINE 1
TOTAL AVALIABLE 4
PH 7.8
TA 70
CYA 20
CALCIUM 250

The pool store said to add dry acid, alkaline Up, and 2 bags of fresh and clear oxidizing shock.

I have already dumped so many chemicals in the pool this season ($400 plus). I am afraid to do anything else.

Last year we dumped 30 gallons of bleach in the pool to break down the combined chlorine and it bleached some of the liner.

Help!

How did you get those numbers? What are the ingredients in the fresh and clear oxidizing shock? Don't add anything else to your pool right now except chlorine. If your CYA reading is correct, then you can either use bleach for your source of chlorine and add some CYA separately or you can use dichlor which will add chlorine and CYA at the same time. If you decide to use dichlor, get it from Sam's. Most other places do not sell plain dichlor but instead sell stuff that has other ingredients that you do not want.

Welcome to the Pool Forum!

A local pool store tested it. The fresh and clear has potassium peroxymonosulfate.

Joyce,
Below is a cut and paste about something Ben wrote previously about potassium peroxymonosulfate:

"Your pool store is creating a problem . . . and then selling you more stuff to fix the problem they've just created. To be fair, they probably don't know that they are creating the problem. Potassium monopersulfate tests as "combined chlorine". So, when your chlorine is low, and you add MPS (monopersulfate), you appear to have the very "combined chlorine" you were trying to get rid of! Glory be! Better add some more MPS; you've got the dreaded "chlorine lock" . . . whatever that is. (It varies from store to store, and region to region.) "

Get some plain, unscented bleach and add enough to get your chlorine up to around 8ppm. Continue to add bleach each evening until your pool can hold chlorine. Don't add any more products right now except bleach.

(If you want to read more, go to www.poolsolutions.com and use the search there to search for potassium peroxymonosulfate. You will have to be logged out (until your registration is completed) to be able to read the search results.

I kind of thought that was the answer. I just can't believe this has happened year after year. Althought I havn't tested for ammonia this year, the last two years I did, and it was very high. My gut thinks it is probably high again.

Why does this keep happening: Could it be "tired water" - I have had the pool for 10 years? Could it be that I use a mesh loop-lock cover? Would it be worth it to invest in a solid one? Would it be worth it to do a partial drain?

Thanks for all the support!!!!

Do you know what your CYA reading was when you closed the pool last fall? A lot of pools have CYA degradation over the winter which results in ammonia which takes a lot of chlorine to break down.

As far as it being the fault of the cover, all covers have their inconveniences. Another option is to not cover it at all in the winter. I don't and neither does Poconos (another of the mods). He has really cold snowy winters up in NE Pennsylvania maybe similar to what you have. I just keep after the pool in the fall, scooping out all the fallen leaves and then shock the pool and raise my pH up to around 7.9 before I lower the water level below the returns and then disconnect the equipment. In the spring, I do have some dirt on the bottom of the pool but that is easily vacuumed out. The water stays clear. I do hook my equipment back up pretty early because the weather gets hot here pretty quick and I need to start being able to chlorinate. Just throwing another option out there for you.

Hi Joyce!
You got some seriously TERRIBLE advice from your pool store.
If your pH is high, and is trending high, the LAST thing you should do is raise Total Alkalinity. And the stuff they sold you to raise it? It's Baking Soda, in a fancy, expensive box. Sometimes they list the ingredient as "Sodium Hydrogen Carbonate" but that's just another name for Sodium Bicarb...baking soda. Sometimes it's called Citrocarbonate...same stuff.

The BEST shock is simplest: plain unscented Bleach, the stronger the better. Or, Liquid Chlorine which is nothing more than double strength bleach.

Dry acid's OK to lower pH, but I wouldn't mess with T/A yet unless your pH won't stay at a level. Generally, if you notice pH rising, a lower T/A is better, and if it's always dropping, a higher T/A can help.

I think you're back to basics: Shock your pool and keep it shocked until it's clear, using bleach.

Or, given your CURRENT numbers, if you have them, simple Tri-chlor pucks in a floater (not the ones with copper) can help temporarily. It will raise your chlorine level, add stabilizer, and is VERY acidic, lowering your pH, addressing 3 issues at once.

But nothing works without lots of testing.

To Watermom: I never thought to check the CYA levels in the fall. So I don't know if it was high. Do you think doing a partial drain would help?

To Carl: Believe it or not, the first time I brought a sample to be tested at the pool store, I think they used someone esles water because it showed the free chlorine as 5 and a low ph. He told me my testing strips were bad. So I added alkalinity up to raise the PH. I did buy 7 gallons of super concentrated bleach last night. How much should I add at a time?

Joyce, here's a simple rule of thumb: Whatever the strength of the chlorine is...5.25%, 6%, 8.25%, 12%...
One gallon will add EXACTLY that much free chlorine to 10,000 gallons of water.

So...one gal of 5.25% adds 5.25 ppm of free chlorine to 10,000 gallons. One gal of 6% adds 6ppm, and so on.

If your pool is 20,000 gallons, you need 2 gallons to get the same effect.

If your pool is 5,000, you need 1/2 gallon to get the same effect.

Adjust accordingly to your pool's size and the amount of bleach/LC you add.