Algae loves my pool

Opened my pool about a month ago. Shocked it once a week and have been vacuuming. Noticed debris on the bottom a few days later after vacuuming where it didn't even look like I vacuumed. We have had no rain since January, and thought it may just be really dusty and that is what was settling to the bottom. Water has always been clear. Then started to notice algae growth.
I have an AG 24' 13K gallons. Sand filter. Sand brand new last year.
I pumped to waste because the algae would come right up with no scrubbing. I shocked with 4lbs of chlor brite from Leslies only to have the algae back on the bottom by the next night. My water levels have all been within range. No phospates, pH 7.4 is fine, hardness fine, CYA is now at 80. Sorry I have no other numbers. Have had my water tested several times and all have been ok. This last time I pumped to waste again, put an algaecide in it, and shocked with another 5lbs of shock only to have the pool green on the bottom again. Leslies pool supply doesn't know what to do at this point and I am sick of spending all this money!! I don't want to ruin the liner with all that shock either. The chlorine is way above normal, and the test kit I have only goes to 5ppm.
What can I do at this point? What kit can I go buy to give ya'll proper readings? The water is clear, not cloudy. The algae keeps coming back really fast. Never had this problem before.
Thanks and glad I found this site!

Hi Mrs;

If you'll look at the Best Guess chart (link below -- but it's no longer a guess) you'll see that with a CYA of 80 you need normal chlorine levels of 5 - 10 ppm, and that the low end of "shock" levels is 20 ppm. It's not uncommon to encounter algae that is not killed till chlorine levels are 2x the shock level.

The test kit you need is the K2006, available via Amazon (link below) for around $60 delivered.

You have three options:

• You can run higher chlorine levels to adjust for your high CYA, or
• You can add sodium bromide via a product like "No-Mor Problems", or
• You can drain 2/3 of your water and refill, lowering your CYA to ~30 ppm.

High chlorine with high CYA is no more likely to bleach your liner than regular shock levels of chlorine with low CYA . . . but there's no way to tell in advance whether your liner's colors are chlorine stable. We've found, in conversations we've had with vinyl sheeting engineers, that liners that look identical have very difference color fastness, and that once the sheeting leaves the manufacturer, there's no way to tell which sort you have.

Sodium bromide works by making your pool a "bromine" pool, at least for awhile. Bromine is not affected by CYA -- which means lower levels can kill algae, but it also means your chlorine consumption will go up.

Draining is straight forward -- unless you have a sunken pool. Most above ground pools can be drained 2/3 with no problem. Most inground LINER pools cannot.

Good luck!

Ben

Thanks Ben,

After reading numerous threads on your forum I was coming to that conclusion. I've had a high CYA in the past and had to drain most of my pool. Should I try to get rid of the algae first? Or go ahead and drain? And...how can I avoid a high CYA in the future? Is liquid chlorine better to use? Been reading lots. Sry for all the ?'s.
I am having a girls weekend (hell yea!!) in a couple of weeks and want my pool ready.

Thanks again!!

Ok last question...Does liquid chlorine or bleach have stabilizer in it? Also, when I get my pool back to normal levels, what do you recommend as an inexpensive weekly maintenance? Just the chlorine or bleach? It gets super hot and humid here and the water temp gets in the high 80's at times. I'm also ordering that kit today!!
Thanks a bunch!!

If you plan to drain and refill some water, go ahead and do that firt. Then test for CYA again and shock based on the chart and new level. The key to killing it all, though, is to sustain that shock level until the pool is blue and clear-- and until you dont lose anh chlorine from sundown to sunup. To keep your CYA down, use bleach or cal hypo for chlorination--no trichlor or dichlor.

Janet

To answer your question, No. Bleach and Liquid Chlorine (which is the same thing, only more concentrated) do NOT have stabilizer. They don't affect pH, add stabilizer, or add calcium. That's why Bleach/LC is the perfect chlorination tool.

Carl

So I am done draining my pool and am now filling it back up. I went ahead and pumped to waste to clean out what I could. Pool looks pretty good.
Anyway, I found 2 gallons of LC named SHOCK that I bought last year. It contains 10% chlorine and doesn't list what the other 90% is. Is that ok?
Also after I get my pool back to normal, should I still use the tablets I have that are trichlor or use something else? If I use bleach all the time, how do you maintain the chlorine that way and how often do you put it in?

Thanks for all your advice!

How much did you drain? Does the shock that you have list sodium hypochlorite as the ingredient? If so, you can go ahead and use it in the pool, but I doubt very seriously that it is still 10% after that much time. Unless you did a total drain and refill (and I hope you didn't!!!), you do NOT want to use the trichlor tabs. Just use bleach. If you use bleach, you just have to test it every evening or at least every other evening and add a little bleach. How much to add depends on what your cya level is. I usually check it every evening and add a little bleach. It takes me no more than 5 minutes at most.

Use the "Best guess chlorine chart" in Watermom's and my sig to determine where your chlorine needs to be, based on your CYA level, and add your bleach accordingly.

Janet

10% liquid Chorine "Shock" is really just 10% bleach (it usually is actually a little higher). Regular bleach is 5.25%, "Ultra" (now the standard) is 6%.

What's the other 90%? Salt water! Yup! Bleach is made from brine (saltwater) as the formula for salt is NaCl...Sodium Chloride. So don't worry about it. If you use nothing but bleach/Liquid Chlorine for 10 years you still wont approach the salt water levels necessary for a pool that uses Salt Water Chlorine Generation (SWG,or SWCG).