High CYA and algae

[drband]

I don't have a good test kit yet, but I will post what my Wal-Mart test kit is telling me. I have a 30,000 gallon in ground pool with a vinyl liner and I am a first year pool owner.


Total Chlorine is between 5 and 10
PH is 7.2
TA is 110
CYA is 100

All my levels where good, but my water was cloudy so I shocked the pool and added 4 or 5 chlorine tablets (both bought at Sam's). My PH was actually a little low (7.0), so I added some PH booster. Now my CYA is really high and I can't clear up the water because of algae. What would cause the CYA to spike like that?

We have had the pool open since the beginning of May. We finally had the water clear about three weeks ago and have been fighting it ever since.

This used to be my grandparents', then my sister's and now mine. Their answer is to shock the heck out of it, but that just doesn't seem right to me.

Please help!

Your CYA may very well be HIGHER than 100. My understanding is that the turbidity (black dot) CYA test is only good up to around 100... over that, and it may be much higher than the test can show. If it is... you may need to dump some water to get it to a manageable CYA level. I'll let others-- more experienced-- recommend a course of action for that. My concern is that it will be difficult to maintain high enough CL with a CYA of 100+ and you will likely get recurring algae problems. Happened to me years ago before I found this forum and the BBB method. Good luck with this-- it is fixable and then your pool will be much easier to maintain.

[tyandnikki]

Thanks so far for everyone's input. When my grandparents had it, they would just keep shocking it until it cleared up. Once the water was clear, their weekly process was to shock it every Sunday night or when it rained. I think that was their only source for chlorine in the pool I don't remember then using the tablets. So, I guess the chlorine from the shock would deminish over the week. Kinda of an up-down pattern in the chlorine levels. I would think that a steady amount of chlorine would be better. They used the same brand that I have been buying from Sam's and I have to say that their water was almost always clear. My sister followed the same routine when she ran it for about 5-6 years without much of a problem. They very rarely had a algae problem.

So, I have both my grandparents and my sister telling me that I need to add more shock and to keep shocking it until the pool clears. This goes along with what you all are telling me on here, but it also seems that I already have or I am developing a CYA problem. Is there another way to test the CYA besides the black dot test to make sure what level it is at?

Thanks again,

Ty

[Watermom]

The disappearing black dot test is the only reliable test for CYA.

[CarlD]

Algae is the canary in the coal mine telling you your water isn't safe to swim in. Algae itself isn't dangerous, but it means there isn't chlorine to fight the bacteria and viruses that get into the water. Each person in the water brings in some fecal matter. That sounds really disgusting even though it's usually a trace amount...But Chlorine blasts it apart to make the water safe. No chlorine, no way to kill bacteria. Plus, at high CYA levels like yours, you need far more to kill all that nasty stuff.
I'm sorry: There is no way around this.

"Shock" is a word to describe powdered chlorine and is usually Di-Chlor. With your CYA level you should not use Di-Chlor or Tri-Chlor (the tablets) again unless your CYA level is low. Both dump tons of CYA (stabilizer) in your pool and that makes YOUR situation worse and worse.
The other powder called "Shock" is Calcium Hypochlorite. You CAN use that but unless it's 60% or higher (48% and 68% are the usual levels) I think it's more trouble than it's worth. Cal-Hypo, the stronger stuff, CAN clear up your pool, but can also make your water cloudy (milky cloudy isn't so bad. Green cloudy is VERY bad).

You can listen to your relatives or us. Not both. Your odds aren't good if you keep tossing in packs of "shock" and it's di-chlor.

If you don't care about fading your liner, you CAN raise your chlorine level very high by adding 15 gallons of 6% bleach immediately, which should raise your chlorine level to about 30ppm (you need to get it to 25ppm just to reach shock level).
Or you could get 12.5% Liquid Chlorine and add 7 or 8 gallons, again, you may bleach your liner a bit.

It's your choice. If you want to protect your liner from fading, you need to keep FC at 25ppm for several days. If you don't mind it fading (like me--my liner's old) you can over-dose it with bleach or LC. By the time all the algae is killed, your FC level WILL have come down.

Still, it's very hard to take care of it this quickly.

If you get it cleared up, you should look at our B-B-B method of pool care. I haven't shocked my pool since early May and it's now July. Why? I understand and follow the B-B-B method. I don't think ANY of the Mods here, or our senior members, shock unless they have a reason to.


Carl

[tyandnikki]

I didn't think you should have to shock that much. How much water would I have to drain out of my pool to get the CYA to an "acceptable" level?

Why do manufacturers put stabilizer in chemicals if it is going to do this to my pool? Hmmm...It sounds like a conspiracy to me.

Again...Thanks for everyones help.

[PoolDoc]

There may have been conspiracies among pool chemical manufacturers, but CYA based chlorine is not the result of one of those, if they existed.

You can operate your pool with your existing CYA level, but you need to
#1 - find out what that level is, by doing the CYA test on pool water diluted 1:1 with distilled water from the grocery. Multiply the result by 2. If the adjusted number is near 200, dilute 3:1 and multiple the result by 4.
#2 - Order a K2006 or K2006C kit so you can test high chlorine levels.
#3 - Use the Best Guess page in my signature to determine what your chlorine levels should be.
#4 - Stop using stabilized forms of chlorine.
#5 - Drain your pool if that's the option you prefer, but ONLY IF you can do so safely. It's not an option, without professional help, on in ground liner pools, or on concrete pools in low wet areas.

Whether you can swim safely this weekend is hard to say, when you don't know what either your stabilizer level, or your chlorine level is. Keep in mind, too, that you don't want to make the news the way that Boston area public pool has, by having found a mom lost for 2 days 'hiding' in the bottom of THEIR cloudy pool.

[tyandnikki]

Well, I drained about a fourth of the water out of the pool and refilled with city water...went to check the CYA level and I didn't have enough reagent. The dip test though looks like it has come down a good amount. It's not down to 50, but it looks to at least be below 100 now. I will let you know all of the readings when I get some more reagent.

When I go to get more reagent, I was going to look for some un-stabilized chlorine and/or shock. I thought about the bleach, but it just seems more conviniant to get the dry form in a bucket instead of having 50 gallons of bleach. What should I be looking for?

Thanks again for everyone's help. I finally feel confident in what I am doing with the pool thanks to you guys and gals.

P.S. I know I need to order the Taylor testing kit. We have to replace our diving board, too, and we were hoping to order both from the same place to save on shipping.

[Watermom]

Many of the granular chlorine products are stabilized. *If* your calcium hardness reading is low (you didn't report it), then you could use some cal-hypo for awhile but not forever. Too high of a calcium reading in a pool can cloud the water. So, even if you do use cal-hypo for awhile, at some point you will have to either switch to bleach or liquid chlorine.