Need help ending vicious stain-chlorine-cycle!

[jenings]

First of all thank you to everyone who has pool problems! (and answers :-D ) :-D The pool store people make you feel like an uneducated jerk when you ask them anything....

Last year you helped me clear some nasty iron stains from my tea stained liner. Put in new sand and shut 'er down for the winter. This year I pulled the cover from my pool in April, liner was mostly fine, water was slightly cloudy buy no green and some debris on the bottom. I started the filter, vacuumed the pool, backwashed and pretty much left it circulating on filter for about a month until I was ready to balance.

CH 0, PH 7.1, ALK 80, CYA 0 (fishy since last season the pool store said it was 300 in August)

So I figured what the heck, while the CH is at zero, might as well finish off those remaining stains. I used the AA method, added Jacks Pink, liner was beautiful for a whopping 2 days. The minute I poured any bleach in the third night, the next morning my liner started to turn. So I added more sequesterant and waited another 2 days to add more bleach. At one point, I think the third cycle, I said the heck with it, I need chlorinated or we can't swim over the holiday. So in 6 weeks, I have been through 4 pints of AA, 1 pint of Oxalic Acid, 8 pints of pricey Jacks sequesterant, and a whopping 60 bottles of bleach Clorox brand. I am not counting the muriatic acid and cyanuric acid since I don't think that's my problem here.

So I guess after I wrote this book my question is - how can I get to shock level with my chlorine without dissapating all of the iron onto my liner? My PH is 7.1, ALK 80, I am religious about those levels, but....All that Clorox, and my FC is .5 and my CC is .5, and I am so invested now, I want to win the stain battle!!!!!

Things I know about my pool - vinyl liner, approx 28000 gal, sand filter, in-line vacuum, and would make a better garden filled in!

 

[JasonLion]

If you use enough sequestrant, and your CYA level is appropriate, you can shock the pool without the stains coming back.

If you haven't already done so, bring your CYA level up to around 40 to 50 as soon as possible.

Figuring out how much sequestrant to use can be tricky. The more metals there are in the water, the more sequestrant you need to use. Sequestrant also wears out and needs to be replaced regularly. It takes some trial and error to figure out the correct level.

 

[duraleigh]

jenings,

Welcome to the forum. Have you tested for metals in your pool water so you know what you're dealing with? That would help you develop a more systematic approach rather than tossing in all the ingredients hoping something will work.

If it tests high (and it sounds like it might) have you priced trucking in metal free water? That's not an instant cure but can take you down a path that will eliminate your need to fight this every year.

I assume your source for water is a well...is that correct?

 

[jenings]

My water tested "trace metals" which makes me suspicious since AA and sequesterant both eliminate my stain problems pretty immediately. I've considered trucked water, but the fire company hauls it from the river which I think is more gross than what's in there already.

I guess I can just plug away at the sequesterant until it seems to level out, but does this eat chlorine? I am baffled because I have not used any clarifier, nor algecide at all this year and my pool has been sparkly, clear, and doesn't smell like socks, fish, or even chlorine but I get minimal to no reading. Does bleach perhaps not register on a OTO CC test or a Aquacheck FC dipstick? My water has been holding around 80 degrees for over a month, its rained, and I've topped off twice with well water, so you would think with no chlorine it would be a swamp? Also, if I am using this forum correctly, it seems suspicious that my CYA could go from 300 to 0 in one winter, and maybe this reading is wrong and the reason I can't get shock level Chlorination? I really don't trust my newbie instincts to attack this, but I am willing to try whatever you would do if it were your pool.

 

[JasonLion]

It is quite possible that you have a fairly substantial ammonia level from all the CYA going away over the winter. Depending on just how much ammonia there really is, this might be very simple or it take a substantial amount of chlorine to get rid of it. If you can, you might want to get an ammonia test from a aquarium store and see if you have a significant ammonia level.

You need to get the CYA level up above zero. With CYA at zero you are losing all of your chlorine to sunlight, if you aren't losing it to ammonia, so there is no way to make any real progress.

 

[chem geek]

If the CYA truly was 300 ppm and now it is 0 ppm and most of this was converted to ammonia that didn't dissipate, then it could take up to 750 ppm FC cumulatively added to clear the pool so in this case it would be far better to replace the water. Do a bucket test to determine the chlorine demand where 1/4 teaspoon of 6% bleach in 2 gallons of pool water is 10 ppm. You could also test for ammonia using an inexpensive test kit from a fish/pet/aquarium store.

 

[frustratedpoolmom]

Here's Jason's step by step instructions for doing the bucket test:

There is a test for extreme chlorine demand that you can do with a bucket, but it is not The Bucket Test, which tests for leaks.

If you have been adding lots of chlorine and FC is always zero (or close), you can do a test to see how much chlorine it will take to be able to hold a FC level.

1) Put five gallons of pool water in a bucket.
2) Add 1 oz of 6% bleach
3) mix throughly
4) wait one hour
5) test the FC level
6) If FC is 10 or higher you are done. As long as FC is less than 10 repeat steps 2 through 6.
7) If FC is 10 or higher on the first round, repeat the entire test with fresh pool water and use teaspoons instead of oz of bleach.

Each oz of bleach is equal to 96 ppm of chlorine. Each teaspoon of bleach is equal to 16 ppm of chlorine.

This test is most useful when you have CC, ammonia, or fertilizer in the water. The results will not be accurate for baquacil, which reacts too slowly, and are only approximate for algae, since you can't safely add chlorine to the pool that quickly and with algae speed matters.

 

[jenings]

Thank you for the insight everyone. I will try the bucket test and test for ammonia when I get home and let you know! The fertilizer comment has me browsing through the forum now though, since I have a gentleman's farm, but it is surrounded by active fields which are regularly sprayed via helicopter in the spring and early summer. I know it gets in my yard because my car is always covered with goo after they fly over...