Backwashing and shocking

Good morning everyone,

My baseline filter pressure is 12 psi. I uncovered the pool June 1 and here it is June 22 and the psi has not changed. The pool stays very clean; the few leaves I've gotten I've fished out with my leaf net. Most debris involves bugs and silt coming down from the trees, and of course it gets filtered with my 1 hp Superpump (sand filter, 20,000 gal in ground). I get a small blob of debris in the bottom of the deep end occasionally and it just takes a minute to hook up my vac hose and take care of it. Of course I brush the pool every week.

If we get no crazy tropical storms this season and my psi stays this low all summer, then theoretically I should not need to backwash at all (I know that dirtier sand cleans better and over-backwashing is hard on the system)? And, if this remains the case, should I backwash anyway when I cover pool in September? Although there will be 8-9 months downtime, I will run pump anywhere from 10-15 times in the overnight hours when temps drop below 28 overnight during the winter months so the pump will not be totally inactive during that time (I live in the south).

* * * * *

With a CYA of 50, when I opened to a crystal clear pool after 9 months down time, I shocked to 15 ppm. Since then I continue to find no combined chlorine. Since I lose about 2.5 ppm a day under full sun I bring the ppm up to 4.5-5.0 each night (with household bleach). So the 24-hour range is 5.0 ppm to 2.5 ppm. I am the only swimmer in the pool most of the time, swimming several times a day, but I think this qualifies for a low bathing load.

Conventional pool advice, we know, tells us to shock every 10 days or so (no matter what), but if I have no CC, and crystal clear water, I shouldn't worry about shocking until I have CC (or signs of algae)? My water is completely odorless and in fact even after swimming there is no trace of chlorine smell on my skin.

One more question: if I get .5 ppm CC should I shock, or wait until I get 1.0 ppm? I apologize that I haven't the time here at work to search the archives. Thank you!

Hi Elsie!

Welcome back--I remember you from "before"....glad to see you've come back to the forum.

Second question first, if your pool is clear, showing no signs of a problem, and not using any chlorine overnight, and you're diligent about keeping your chlorine up adequately, then you could certainly wait until you get 1 ppm CC before shocking--I don't remember where you live, but in many cases the sun will take care of a 0.5 CC before dusk sets in. Almost all pools will have 0.5 at some time, mine almost always does for an hour or so after the kids get out (sweat, sunscreen, dirt off the toys, etc) but it's usually gone by dark. You mentioned tropical storms--I do ALWAYS shock my pool after a hurricane has blown through, though, or after a several-day rain event, even if the numbers are good, because you just never know what the rain will drop into your pool.

As far as your filtering goes, if your pool is very clean, I wouldn't expect your pressure to rise, and I see no need in backwashing it until the pressure does rise. I would, however, backwash it before closing--you don't want all the "gunk" in there from a whole season having all that time to grow bacteria and other stuff that you'll have to kill off when you reopen.

Janet

Hi Janet,

All excellent advice, thank you so very much! I'm in central Alabama (a transplant 8 years ago after 47 years in my native Minnesota). As I recall you're in Louisiana and keep a CYA of 100 because of the nonstop hours of full sun on your pool...funny what things stick in our minds (assuming my memory is serving me correctly). Of course these days the mention of LA--at least coastal LA--conjures up very sad thoughts. Tragic beyond words.

Thanks again for confirming my thoughts on the backwashing and shocking! And I'll "see" you around the forum!

Quote:

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Originally Posted by elsie

As I recall you're in Louisiana and keep a CYA of 100 because of the nonstop hours of full sun on your pool...funny what things stick in our minds (assuming my memory is serving me correctly).

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Yup, that's me! Still down here, oil slick or not :p

Janet

Hi everyone! I'm new to The PoolForum so if my post is out of place, please feel free to move it.

We are having an issue with backwashing and shocking our pool it that we have done it more to our new pool installed four months ago, than we ever did with our old above ground pool. It involves an algae issue but after reading the posts in the algae forum, I decided to post here because in the last 15 years we've had above ground pools, we have primarily use a shock product - and an occasional clarifier product... and never checked any water levels! I vacuumed the pool every other day and my husband backwashed every other week or so. We never had any problems like this before.

I am vacuuming the pool AT LEAST once a day, in the morning, and before the sun sets, the bottom of the pool is covered with a fine green/brown dusting as described in the algae forum. And I have to backwash AT LEAST TWICE before I finish vacuuming!

We will try the DE and filter sock (if I can find one) and I will attempt to find a water tester so I can provide you with the levels. Meanwhile, I need to find some kind of primer on pool maintenance and what all the abbreviations mean and how to deal with each.

Meanwhile, can you tell me if I'm destroying our filter by backwashing so much? (The Doughboy documents are very sparse)

Thanks for your time!

Hi, Judi,
Welcome to the forum!!

For right now, backwashing your filter frequently is much better for it than letting the pressure get too high and overloading your pump. It shouldn't hurt the filter; however, if you're having to backwash that often, there are obviously problems with the water that you need to address.

Does your filter have a vacuum to waste mode? That would allow you to still vacuum but to bypass the filter so the frequent backwashings wouldn't be necessary.


By "occasionally using a shock product and a clarifier product and not testing any water levels", you may have created a pool that's going to take some time and patience to fix, but I'm sure we can help you with it.

If you'll have the water tested with a drop-based kit (no strips!) and post numbers for at least two of the three: Free Chlorine, Total Chlorine, Combined Chlorine in addition to pH, Total Alkalinity, CYA (stabilizer), and Hardness, I'm sure we can help you get the algae problem fixed so that you don't have to spend nearly as much time vacuuming.

We also need the ingredients of the chems you've been using in the pool (specific ingredients, not just "shock").

Also, you really need to get a good, drop-based kit so you can do your testing at home and make sure that your readings are accurate. In order to clear up an algae problem, this is going to be key. We recommend the Taylor 2006K, which can be found online. Leslie's also has a relabeled version of that kit on their online site.

In the meantime, read through the "stickies" at the top of the forums--most of the general water chemistry basics and methods are in those stickies. You can also check out our sister site PoolSolutions.com and there's LOTS of information there that will help you understand what's going on with your pool. And, of course, we're here to help!! It will be helpful if you'll just keep all the information regarding this situation in this one thread, so that all the people trying to assist you have all the info in one place.

Janet

OK Janet, got a test kit from Leslie Pools today... here goes:

FC = 2
TC = 3
CC = 1
PH = 7.5
TA = 150
CYA = 70

The pool looked great yesterday. I wasn't able to vacuum this morning and took the readings this afternoon when I got home. Pool's green on the sides and around the base. Now it's raining like mad... we're getting rain bands from the hurricane...

I don't have the filter sock or DE yet.

Thanks again for your time.

Judi

Hi Judi,
Not Janet here, but hope I'll do!

With a cya of 70, your chlorine levels are not near high enough to keep algae from forming much less to fight it!

Stabilizer . . . . . . Min. FC . . . . Max FC . . . 'Shock' FC
=> 0 ppm . . . . . . . 1 ppm . . . . . 3 ppm . . . . 10 ppm
=> 10 - 20 ppm . . . . 2 ppm . . . . . 5 ppm . . . . 12 ppm
=> 30 - 50 ppm . . . . 3 ppm . . . . . 6 ppm . . . . 15 ppm
=> 60 - 90 ppm . . . . 5 ppm . . . . . 10 ppm . . .. 20 ppm
=> 100 - 200 ppm . . . 8 ppm . . . . . 15 ppm . . .. 25 ppm

As you can see in the chart above, you need to keep your cl between 5-10 ALL the time and when you need to shock, you'll need to take it up to 20ppm. Since you are reporting a CC reading of 1, and you have low FC level and you are seeing algae, all these things tell you that you need to shock the pool and try and hold the cl at 20. The more times per day that you can test and add bleach to get your cl back up to 20 the better. The very minimum is twice per day: early morning and in the evening when the sun is off the pool. But, if you can test 3 or 4 times per day it will clear up faster. The key is to sustain the high cl reading and not let the FC yo-yo up and down. When you get to the point where you are not losing more than 1ppm of cl from sundown to sunup and when you have a CC reading of 0 and no more algae, then you can let your cl drift back down to between 5-10. Never below 5 however or you will fight algae again. Also run your pump 24/7 while you are trying to clear this up. Also, brush the sides and bottom of your pool daily.

What exactly have you added to this pool -- meaning ingredients, not just "shock"? Your cya is already high at 70 so you really shouldn't use any trichlor pucks or dichlor powder in your pool. Best to stick with bleach or liquid chlorine.

What is the volume of your pool?

Thanks Watermom!
Our pool holds 8000 gals. We have always exclusively used a product called Shock PLUS (by aqua chem). They are 1 pound packets that treat 12,000 gals. I don't know why we started using an entire packet per treatment, but we did. Like I said before, our problems started three months ago with our new pool. The active ingredient is sodium dichloro-s-triazinetrione (58.2 %). The remaining 41.8% is "other ingredients". The package instructs to use once a week to create sparkling water, reduce chlorine odor and eye irritation, and does not increase pH.

I can work on the pool in the morning and evening, but for the rest of the day, this being Texas, the sun is unmerciful. Could it be the sun? We lost a shade tree and one of our pool umbrellas so we have many more hours of direct sun on the pool this year. In any event, I will start the bleach regime and let you know.
Judi

In your pool, each quart of 6% bleach will raise your cl level by just about 2ppm. Also, with a cya level of 70, you shouldn't use any more dichlor (shock plus packets) as they are stabilized (which means they have cya in them) and you don't want your cya any higher.

Keep us posted!

You bet Watermom! Thanks ever so!

Watermom - I'm really, REALLY, new to this testing stuff, so please bear with me (after you finish laughing).

I started this morning at 7 am; I vacuumed then backwashed; I added 1 quart of bleach which resulted in the following levels: FC - 5; TC - 5; CC - 0; and pH 7.8.

At 2:30 I added another quart of bleach and got the same levels.

The little measuring container has two ports; one labeled Cl Br, and the other labeled pH.

The Cl - Br side looks like this:

Cl Br
5 10
3 6
2 4
1 2
.5 1

The pH side:

pH
8.2
7.8
7.5
7.2
6.8

My question is: How do I measure 10pmm and 20pmm if it's not marked on my container? The kit I got from Leslie Pools cost $47. Is there another kind of measuring container with higher levels on it? Am I making any sense?

Thanks for your patience...perhaps we should move my posts to kiddy/remedial?

Judi

I hate that you already spent $47 on a kit, because you really need a better kit. We like the Taylor K-2006 and it will let you test higher cl readings than just 5ppm. Read more at this link:

http://www.poolforum.com/pf2/showthread.php?t=10006

In the meantime, you can make your kit go higher than 5 by using dilution. Take one part pool water and an equal part of distilled water, mix, and then run your test with this. When you get your result, multiply by 2. To go higher than that, take one part pool water and two parts distilled, multiply results by 3, etc. This dilution method is not super accurate but is better than what you can do now. You really should consider a better kit. It will pay for itself in no time by avoiding problems in your water.

How does the water look? You are not adding enough chlorine at a time to get to shock level. When you test, add enough bleach to take your cl level back to 20. Each quart adds 2ppm so if you test and it is 5, then you need to add 15ppm which would require 7 or 8 quarts of bleach added all at one time. If you don't take it to shock level, you will never clear the pool. Try and test at least two or three times a day and each time raise the cl back up to 20. If you do this consistently until you can go overnight without losing more than 1ppm of cl, then your pool should clear right up. After you can hold cl overnight, then let the cl drift back down to 5-10.

BTW -- Don't worry about asking what you think are silly questions. We were all once pool newbies. You'll get the hang of this and before long, you'll know exactly what to do.

Just a caveat:

If your kit is the "DPD" kit, using the "DPD" test for chlorine, you cannot use the dilution method--that only works on the OTO chlorine test.

But the good news is if you can find an OTO kit that measures to 5ppm (and they are around although most are only good to 3ppm) you can use dilution with that--and they aren't expensive. You CAN use dilution with a 3ppm kit, but you have to dilute the pool water with 4 parts of distilled water to measure to 15ppm. With a 5ppm OTO kit you only need to dilute with 2 parts of distilled water to get to 15ppm--far more precise.

CarlD - Watermom

DPD? OTO? I can just barely see under the sticker on the front of my test kit... it is DPD. I guess I stopped reading when I saw the name "Taylor Technologies" on the label.

I have a headache... I think I'll have a R-0001 on the rocks and go to bed.

Thanks

Quote:

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Originally Posted by jmcrae

DPD? OTO? I can just barely see under the sticker on the front of my test kit... it is DPD. I guess I stopped reading when I saw the name "Taylor Technologies" on the label.

I have a headache... I think I'll have a R-0001 on the rocks and go to bed.

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Phosphates on the rocks. Yummy. :rolleyes:

Does your Leslies kit contain tests for Total Alkalinity, Calcium Hardness and Cyanuric Acid (CYA)? If not, would recommend that you get the Taylor Complete FAS-DPD Test Kit K-2006, competitively priced at Amato Industries and Poolcenter.com.

If your kit already has these other tests, you can pick up a FAS-DPD chlorine test for about $21, here.

Sorry!

There is a learning curve on chlorine tests. There are 3 tests:
1) OTO. This is simple and reliable and comes in the cheap, $5-$10 test kits that test chlorine and pH. But it's got two limitations--the kits usually only measure to 3ppm and a FEW go to 5ppm--we frequently need measures up to 15 to 25ppm. Also it only measures Total Chlorine. The good thing about OTO is the color gets more and more intense with higher chlorine even if you cannot measure it.

2) DPD. This is a test capable of measuring chlorine levels up to about 10ppm--but the test kits rarely go above 5ppm. It can measure both Free Chlorine and Total Chlorine, allowing calculation of Combined Chloramines (which, if more than 0 means something's growing). But above a certain point, the chlorine BLEACHES the tests making them look like you have NO chlorine. For these reasons I don't like DPD.

3) FAS-DPD. This is the gold standard. You don't need to recognize shades of color--you add a powder to get a colored solution and then you add drops until it goes clear again. You can safely measure up to 50ppm of Free Chlorine and it also measures Combined Chloramines. (you get TC by adding Free Chlorine and Combined Chloramines). If you use FAS-DPD testing, you don't need to use any other chlorine tests.

Also there are strips, but to me, they only indicate if you have LOTS of chlorine or need to measure it with OTO, DPD, or FAS-DPD.

Thanks Polyvue and CarlD.

I appreciate the input. It rained tons last night (due to hurricane Alex) so I'm in the pool to vacuum and backwash. There's lots of stuff on the bottom but nothing on the sides yet. I'll check back in when I get the FAS kit and post the new levels. Meanwhile, I'll vacuum, backwash, bleach, vacuum, backwash, bleach, .....

Once the fallout from Alex is over with, I would definitely shock the pool--goodness only knows what kind of crud came with the rain from the gulf!!

Janet

I vacuumed this morning at 6:30 and put in 7 quarts of bleach. By 4:00 pm, the pool was full and I could see a layer of brown on the bottom. It's almost 7:00 pm, I've had to let more water out of the pool (so much for the bleach!), and it's still raining cats and dogs. I'm setting the alarm for 3:00 am ... thanks so much for all your encouragement everyone!

Hey, I'm back!
My pool hasn't beat me yet. Hurricane Alex almost did! We had constant rain in Katy... 26 miles west of Houston ... for two days. Needless to say, lilly-livered coward that I am, I did not venture into the pool for any length of time. I took advantage of breaks in the rain to vacuum when I could and every time I vacuumed I backwashed to waste (Alex was doing just great in replacing the water!) and I dumped a gallon of bleach morning and night.

Every time I looked at the pool after dumping the bleach, I had a visible layer of algae... but it decreased with each application. Yesterday evening I vacuumed just before sunset, poured another gallon of bleach and lo and behold, this morning I had negligible algae!!! I vacummed, dumped another gallon of bleach and raced to WalMart to get some distilled water. I did the 3-1 (OTO) ratio for the Chlorine: FC/15; TC/15; I did the regular DPD test for the rest: AK/140; pH/8.2; CYA/55.

The water is beautifully clear.

Did I do good?

Yep. You done good! Tonight, test the cl at sundown and then early tomorrow morning and see if you lose more than 1ppm. If you do, shock it back up. Continue keeping high cl until you can hold it overnight. Also, retest your pH whenever your cl isn't high so you can get an accurate reading.

Will do.
Thanks to all for your wonderful assistance!

Quote:

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Originally Posted by CarlD

Just a caveat:

If your kit is the "DPD" kit, using the "DPD" test for chlorine, you cannot use the dilution method--that only works on the OTO chlorine test.

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Carl, not true!!!!!

In fact, there are instructions for dilutions on the lid of the Taylor K-2005 (and the equivalent Leslies kit) and the comparator has markings molded in for 1:1 and 4:1 dilutions. While it is more cumbersome than using an FAS-DPD kit it is no diferent from doing dlutions with OTO and it give more meaningful info since you can test both FC and CC and not just TC.
If the sample is diluted low enough it doesn't bleach out.
I suspect that the $47 Leslie's kit that jmcrae said they bought is the rebranded K-2005 that Leslie's sells.

I checked the kit I got from Leslie's - It says it's manufactured for Leslie's Swimming Pool Supplies by Taylor Technologies, Inc. and the Pool & Spa Water Tests sheet says Taylor 11/05. The back of the instruction sheet is filled with instructions to raise chlorine level by 1ppm; superchlorinaton for algae removal; to raise pH with soda ash; to lower pH with muriatic acid; to lower pH with dry acid; to raise total alkalinity with baking soda; to lower total alkalinity with muriatic acid; to lower total akalinity with dry acid; to raise calcium hardness with calcium chloride.... but no dilution instructions.

That's why I did the chlorine test with my little Walmart OTO chemicals; and the rest with the Leslie's DPD test kit.

Was I wrong? Should I have done all the tests with the same chemicals?

Use the Taylor kit for all tests. What does your kit test for?

Chlorine (free, combined, total) / Total bromine test;
pH test;
Total Alkalinity;
Calcium hardness (I have an above-ground pool with vinyl liner); and
Cyanuric Acid test.

Oh... and also Acid Demand Test and Base Demand Test

Does your test kit use the same larger comparator tube for testing pH, TA, and CH and use the small chlorine tube for the CYA test? If so then you have the K-2005 and you might seriously consider addding a stand alone FAS-DPD test since that is the only test that is different in the better K-2006 kit.
If your test kit has a small tube for the pH test (same size as the chlorine test) and a separate large tube for the TA and CH tests then you might want to consider getting a K-2006. It is a much better test kit.

My kit came with four devices. Chlorine and pH are tested in the same container - one side for chlorine and the other side for pH.

The TA test and calcium hardness tests are performed in a different container - looks like a tall shot glass with ml measurements 5mL to 25mL - no top.

The CYA test involves using two containers - one for mixing the chemicals and when the solution is cloudy, pouring it into a very slender tube with a black dot that is supposed to disappear when viewed from the top and the tube is then read at liquid level.

You have a K-1005, which you can get directly from Taylor for $39.05 plus shipping. It is ok but for just a bit more money you could have had a much better test kit.

The TA, CH, and CYA tests are the same as in the K-2006 so they are what you want to have.

The pH test is not as precise as the one in the K-2005/K-2006 but usable. It is better than most other pH tests, FWIW.

Be aware that this kit uses pH reagent R-0014 and NOT R-0004 when you need to get a refill. The acid and base demand tests in this kit are not that trustworthy. The K-2005/K-2006 is much better at these tests.

The chlorine test is a DPD test and your comparator does not have the dilution markings on it that the K-2005 kit has so you would have to do the dilutions in a different container first.

I would still add a stand alone FAS-DPD test to this kit as Polyvue mentioned in his post above. This will give you the functional equivalent of the K-2006, which is the kit most recommended here and on other forums. The advantage of FAS-DPD testing over DPD testing is that you can test up to 50 ppm FC with a precision of either .5 ppm or .2 ppm. There are no dilutions involved and there is no color matching. It is a drop counting test that turns from pink to colorless and it basically foolproof. It is a bit slower and slightly more expensive per test but its advantages far outweigh its disadvantages. This would have you all set as far as water testing goes!

Hope this info is helpful.

Thanks Waterbear!
Your information has been very helpful and informative. I have a much greater respect for my pool.
I am going to get the FAS-DPD. I'm very interested in just what "precise" looks like.
Thanks again to everyone.
Judi

Joecus ---
I split this thread and moved your question and Waterbear's reply into a new thread titled: Hot climate = Optional high CYA. Please continue there. Thanks.

Quote:

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Originally Posted by Watermom

Joecus ---
I split this thread and moved your question and Waterbear's reply into a new thread titled: Hot climate = Optional high CYA. Please continue there. Thanks.

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Thanks! ;)