algea in pool

[tara15]

Hello,

I have a 15,000 gallon above ground pool. I have had many algea problems this year. i have used the polyquat, shocked it and no luck. it was blue for one day, and then green again. here are my test results as of 10 minutes ago

ph. 6.8
fc 7
ta 80
cya 100

ive tried shocking all the time, we have the chlorinating tablets in the pool. i just dont know what to do anymore. any help will be appreciated.

thanks

[ivyleager]

With a CYA of 100, you're going to need to shock (super-chlorinate) up to the 20-25ppm level and hold it there until you no longer have any combined chlorine (CC). I have a feeling you've been yo-yo'ing w/ your shocking. One gallon of 6% bleach will raise the chlorine 6ppm per 10,000 gallons. So, on a 15K gallon pool, one gallon should raise you 4.5ppm. You'll need about 5 gallons of bleach in your pool to initally raise it up to 20-25ppm level. Make sure you're running the filter 24/7 during this process. Backwash as needed as algae can gunk up the filter.

Also, your pH is too low and may be lower than 6.8. Most test kits don't test below this level, so I'd do this first. You'll need to bring that up to 7.2 at least.

Stop using the chlorinating pucks. They drive up CYA and drive down pH. Begin using bleach only for chlorinating. You'll find a lot of information in the chlorinating section http://www.poolforum.com/pf2/forumdisplay.php?f=132
as well as tons of tips to get you started http://www.poolsolutions.com/tips/10things.html


Good luck.

CaryB

[tara15]

ok. so i first added about 4 pound of baking soda to the pool and retested about a half hour later. the readings are as follows

fc 10
ta 120
ph 7.2
cya 100(still)

i added about 2 gallons of bleach for now since that is all i have on hand until i go to the store. do you still think i need 5 gallons? also, we noticed when we didnt have the pucks in the floaters, the algea problem got worse and we were shocking more. how often should i add bleach to the pool? when is it safe to go back in the pool?

[Watermom]

You say "still 100" when referring to your cya reading. It isn't going to come down - unless you do a partial drain. If you use more pucks, it is going to continue to rise which you don't want. Take a look at the Best Guess chart in the following link.

http://www.poolforum.com/pf2/showthread.php?t=365

Yes, you need to shock up to 25 since your cya is so high or you won't get rid of the algae. How often? Test at least 3x a day (more won't hurt!) and EACH TIME add enough bleach to get your cl level back up to 25. The key to killing algae is to sustain the high reading and not let it yo-yo up and down. In a pool this size, each quart of 6% bleach will raise the cl by 1 ppm. Also, run your pump 24/7 for now. After your algae problem is gone, you'll need to keep your cl between 8-15 all the time because of your high cya or you'll have another algae bloom.

Another option is to do a partial drain and reduce your cya to about 50 which would be ideal. It is up to you. Partial drain or just run higher than normal cl readings. Either way will work - it is up to you.

Your ph and alk are OK now. If your ph drops any, you'll want to use Borax to raise it instead of baking soda.

[tara15]

the only reason i said still 100 for cya was that the test strips said that the ph and alkalinity affected the cya reading. also, where can i get test strips that give you a number higher that 10 for free chlorine? do i have to buy them at the pool store? i also have a dog who like to swim in the pool. is it safe for her to swim if she doesnt mind slightly green water or should i wait?

thanks

[Watermom]

We don't recommend teststrips because they aren't very accurate. Most of us use the kit that Ben sells at the sister site to this forum www.poolsolutions.com. It WILL test high cl levels which you're going to need to be able to do if you decide to keep your cya of 100. At the very least, buy the 5-way drops based kit at Walmart for about $15. It won't test cl higher than 5, but you can dilute the sample and make it test higher. However, just be aware that with each dilution, you do lose some accuracy. To dilute - take one part pool water and two parts distilled water, mix them together and then test as usual. Then multiply the result by 3. (If it were my pool, I'd do the partial drain and lower cya to 50. Just my opinion.)

About the dog - dogs swim in green ponds all the time so............. but, I probably wouldn't let it swim in the pool when it had been shocked so high.

Hope this helps. Keep us posted how things are going.

[tara15]

ok here we go again....

I took some water to the pool store for analysis. these are the results

fc 5(thats all they go up to so it could be higher)
ph 7.6
ta 150
cya 50

so now what? i added 2 gallons of bleach, waited a while and brushed and vacumed the pool. do i wait and see now?

thanks

[Watermom]

Your cya level is drastically different than before. We are always leery about pool store readings and test strips so I don't know which one to believe. Also, since it could be 50, I am now skeptical to tell you to shock up to 25 as we suggested before when we thought your cya was 100. Can you go and buy the drops based kit I suggested above and test the cya yourself? We put more faith in test results that we do ourselves. You should also run the cl test yourself and use the dilution method I described above. Then repost and we'll go from there.

[tara15]

ok....

i got the test kit with 5 drops and the strips as well to compare...i know you dont like the strips.

here are the results

total chlorine(by diluted it the way you told me to) 15 or even higher
cya 70
ph 7.2

test strip
free chlorine over 5
ph 7.6
ta 150
cya 100


ok so now what?

[Watermom]

I'm more inclined to go with the results from the drops based kit rather than teststrips, so we'll assume the first results are somewhat accurate. Keep your chlorine level between 15-20 for a few days. Test and redose with bleach as often as practical to take it back up to that level instead of letting it drop much. Run your pump 24/7. That should clear your pool. Keep an eye on your ph. Don't want it to go lower than 7.2.

Keep us posted how things are going.

EDIT: I'd still consider a partial drain to lower that cya level.

[tara15]

ok. so things are ok so far. pool looks a little less green i think. i backwashed this am and a lot of green came out so thats good. levels are still holding. ph is at 7.2 and i dont want it to drop so how much borax would i add to increase it if needed? I might just leave the cya alone for this season since only about a month or so left. once i get the pool blue and cleared up, do i still need to maintain a fc at 15-20? if so, is that safe for people to swim in? thanks

[Watermom]

PH is OK at 7.2, but if it drops any, add Borax slowly so you won't get it too high. I'd probably do no more than a fourth of the box at a time.

Keep your chlorine at shock level. Glad it is looking better - but keep hammering it with bleach. Test it at least 3x a day and each time, take it back up to shock level.

After the pool is cleared, keep the high cl for one extra day as insurance and then you can let it drop back down. But, with cya of 70, you'll want to keep it between 5-10 ppm all the time and yes, it is safe to swim in at that level.

[tara15]

ok...so ive been testing the water at least 2 times a day. the ph is staying at 7.2 and the fc is at least 15. i tried diluting it a little more and multiplying by 4 and it was still very yellow. the pool cleared up dramatically where it is now clear, but still a little green. ive been adding 1.5 gallons of bleach daily, backwashing daily and vacuming daily. I got up A LOT of algea. so, how much longer do you think before the pool is blue again? also, how do you guys feel about the phos free solution to keep algea from feeding? thanks for all of your help.

[duraleigh]

Tara,

I am pretty sure you are not using enough bleach. 1.5 gal daily will only raise your pool 6ppm. I don't know where your chlorine level is now but, if you'll post that, someone here will advise you on how much more to add so your pool will clear more quickly. My guess is the delay in clearing your pool is not getting your chlorine high enough.

Save your money on that Phos Free stuff...you don't need it....you need chlorine.

Oops! I misread your post. I see now where you say your Cl is around 15ppm. That's good. Be sure to check it again this evening and add enough to bring it right back to 15ppm...a little higher won't hurt....Did you ever determine a more accurate CYA level?

[tara15]

according to the walmart drop set, my cya is around 70-90. i just tested the water, this time diluting 4:1 and multiplying by 5 and it is still very yellow. so, probably at least 20. i dont know how unaccurate it becomes the more you dilute it, but it is not getting any less yellow. with a vinyl liner, im afriad to put too much bleach in the pool.

[duraleigh]

Yeah, you don't want to go crazy with the bleach. It sounds like you are just about at the right level.

Do your best to keep it right at that level and I think you'll see some pretty dramatic improvement in the next day or so. As a reminder, keep running your pump 24/7 'til your water is nice and clear.....I think you're pretty close.

[tara15]

sorry, but i have yet another question. the pool is slowly clearing up as i said before, but it seems to have stopped. its clear, but light green. when i vacuum, it gets green again, and cloudy but then clears up. In the past, we have used first aid to help clear up the pool. We have the blue stuff now. should i use that to help things along or just wait it out? I seem to be adding 1.5 gallons of bleach daily and just maintaining this color now. what else can i do? im getting frustrated!!!!

[aylad]

Adding other stuff isn't going to help it clear up faster, and it's going to cause you more problems. Save the money on the other stuff, and spend it on the bleach--chlorine is what will kill the algae!! When you vaccuum and it gets green again, you're seeing algae that isn't dead yet. Keep the Cl level up to 20 ppm, and it will clear....

Janet

[tara15]

hooray....the pool is blue and clear. its not sparkly yet, but that will come next i hope. thanks to everyone for all of your help and patience.

[tara15]

hello everyone again.

just a quick question.. my pool is looking great thanks to all you guys. the only problem is that my chlorine is now down to zero. I let it drop down to the 8-15 range, and then i havent added bleach since the other day. do you add bleach daily? all my other numbers are still the same. thanks

[aylad]

Yes, you need to add bleach each time it drops below 8. IF you'll test for chlorine daily for awhile, you'll soon start to get a feel for how much you lose in a given day, and will be able to anticipate when to add the bleach.

Glad the pool is looking good!

Janet

[tara15]

im back again. everything was fine until i went on vacation. I had my mother in law watch and bleach the pool to no avail. the pool is now completely green. she said she put a 3 quart bottle of bleach in the pool per day but im not so sure. And now, my drop test kit is missing, and walmart doesnt have anymore pool supplies. Im using the test strips and they say the free chlorine is 10+. I also forgot to mention that my pool is covered at least 50% by a tree with leaves and debris falling in. I have spent so much money in this pool, that i feel like draining it completely, cleaning up the remainng algea and starting from scratch. I dont know what to do anymore. do you think the tree could be the problem? any help would help

[aylad]

Three quarts of bleach in your pool is only enough to raise your Cl by about 3 ppm daily. With a tree constantly dropping stuff in your pool, and with your CYA level as high as it is, your chlorine demand is much higher than that. You need to get your pool back up to shock level until it clears up again, and it will probably take a few days.....and then when you let it drift back down, don't ever let it go below 8, or you are going to have continual algae blooms.'

Janet

[threekittens]

You are using distilled water as instructed right when you do the dilution?

[tara15]

yes, i was in the past. But like i said in my last message my drop test kit is now missing, so i can only use the test strips. I will order the test kit here, but it might take a while.

[tara15]

hello again. so after about a week of shocking to about 25 my pool is now blue and clear. its been like that for about a week and im keeping my fc at about 15 to be on the safe side. i just have one more question. even though my pool is clear and blue, it does not have that sparkle that it used to have in the past. is there anything i can do to acheive that?

also, thank again for all of your help. I now have an understanding of my pool

[Watermom]

Do you have a sand filter? I quickly scrolled back through this thread and didn't see where you told us what type of filter, although I might have just missed it. Many of us with sand filters have been adding a little DE to it to help catch the really fine stuff that the sand filter might not get. If you decide to try it, premix it with some water and pour it in the skimmer while the pump is running. You only want to add a little - enough to raise the filter pressure by 1 psi. Add a cup or so and then wait 20 or 30 minutes to see if it rises. If not, add a little more. Continue slowly until you see the pressure rise by 1. This might help you get your sparkle back! Good luck.

[tara15]

I have a sand filter. The only problem is that the pressure guage is broken. My mother in law didnt bring in the filter last year and it cracked and broke in the ny winter. Is DE earth? should i try to add some anyway? Its been so cold and rainy here on long island that i might just close up the pool anyway. If i do, should i try to change the sand next year and if so, do you reccommend any type of sand? I heard of this stuff called "zeobrite". Have you heard anything about this type of media? sorry for so many questions.

[duraleigh]

Tara,

Before you invest in zeobrite (or anything else), replace your pressure guage. It is a valuable tool in pool management and will cost you less than Ten bucks.