Loosing too much chlorine during the day, not at night

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pool4thekids

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May 22, 2009
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Hi,

We have had a 30,000 gallon, de filtered pool for a year now. We live in very sunny Texas. Up until the last few months we paid a pool service to maintain our pool chemicals for $60/month. We never had a problem with the pool and we never checked any of the levels. After reading your site, they may not have been maintaining a good sanitation level, but like I said we never had any problems. My husband lost his job a few months ago, so we decided to let the service go (spend the $60 on food :-D ) and maintain it ourselves. We went to the pool store and bought (all the wrong) chemicals as recommended. We used the Dichlor and Triclor for 2 months and we had our water tested every week at the pool store. We watched our CYA level rise from 70 to just under a 100 before we started to question pool store as to what CYA was and why it was rising. That is when I stumbled across your website and we immediately halted all use of stabilized chlorine. We currently sit at 100 CYA which I believe is accurate since we watched the number steadily grow. We now use the BBB method and try to maintain a FC level within 8 - 13. We do not have a great test kit (actually palin dpd) but are very close to a pool store so are relying on their testing. Our plans were to only do our own pool until new employment and then rehire our pool service, so a $80-$100 investment in a test kit did not seem logical (that's a lot of trips to the pool store) :) We are not losing FC levels overnite (I have verified this over several nights, testing in the evening and at 8 AM when pool store opens), but during the day it seems that we will lose 3 -4 PPM each day which means that we are using about 2.5 jugs of ultra bleach (174 oz size jug) every 2 days. So we are spending almost $20/week on bleach. This does not seem "inexpensive" to me, especially when our pool sevice was $60/month. I understand the logic behind a high CYA, but I assumed(probably incorrectly) that once we brought the pool up to the high level of FC required to maintain sanitiation with associated high CYA that it would remain at those levels longer so the relative cost of bleach would be the same as pools with a lower CYA once the initials dosages were applied. What am I not understanding? Doesn't $80/month seem too high (it's PB&J until we figure this out :?

Thanks for your help

Here are our latest test numbers

FC 11 PPM
CC 0 PPM
pH 7.6
CYA 100
CH 305
TA 70 (Pool store recommended to raise this to 80 but see that 70 is acceptable in the pool calculator)
 
Welcome to TFP!

I suspect that you are losing FC overnight and have a low level algae problem. The DPD test is not precise enough to measure overnight FC loss, especially if it is small as yours would be.

At very high CYA levels, or with a SWG, you can get into a situation where algae is growing and constantly being killed so that the algae never takes over and yet never all dies.

You either need to do the overnight FC loss test again with a FAS-DPD test, or shock the pool.
 
Thanks for your quick reply,

When I make my next chlorine addition in the evening (either tonight or tomorrow night) would it be sufficient to wait 1 hr. take a sample to the pool store for testing and then take another sample to the pool store at 8AM the next morning for testing? Do pool stores generally have enough accuracy to test for small overnight FC loses? This is what I have done in the past.

If I do have overnight FC loss, how much is acceptable or should it be zero? I know I have read somewhere that sometimes an "algea killer" is actually acceptable to use with a high CYA. Assuming I actually read this I suppose I have at least 3 options that I can think of right now.

1) Shock up to 25 FC level with bleach
2) Shock up to 25 FC level with calcium hypo (realizing that this would raise my CH but we have a plaster pool so that might be acceptable for an occaisional shocking)
3) Use an "algae killer" plus associated bleach

I am trying to get an idea of how much you think the BBB method should cost per month during summer Texas weather, 30,000 gal, DE Filtered? Any ideas? Like I said if it is more than $60/month I would certainly consider rehiring our pool service. Our water is crystal clear by the way. If it is just an initial big investment and then costs should go dramatically down, I would like to continue my own BBB. If cost is about equal I can't justify a (100 lb.) woman lugging 10 jugs of chlorine from the grocery every week and several trips to the recycling center to dispose of the containers.

Thanks for you help!
 
pool4thekids said:
...30,000 gallon, de filtered pool for a year in sunny Texas...lost his job so we decided to let the service go and maintain it ourselves...watched our CYA level rise from 70 to just under a 100..then immediately halted all use of stabilized chlorine...currently CYA @100...which I believe is accurate since we watched it grow...now use BBB method and try to maintain a FC level within 8 - 13...not a great test kit (plain dpd)...close to a pool store so rely on their testing...plans were to only do our own pool re-employment then rehire our pool service, so a $80-$100 in a test kit did not seem logical...
We are not losing FC levels overnight...during the day we will lose 3 -4 PPM each day so we're using 2.5 jugs of ultra bleach (174 oz size jug) every 2 days: almost $20/week on bleach...not "inexpensive" when our pool sevice was $60/month...understand the high CYA, but I assumed that once we at the high level of FC required to maintain sanitiation with associated high CYA that it would remain ther so the cost of bleach would be the same as pools with a lower CYA...Doesn't $80/month seem too high :?
Here are our latest test numbers
FC 11 PPM
CC 0 PPM
pH 7.6
CYA 100
CH 305
TA 70 (Pool store recommended to raise this to 80 but see that 70 is acceptable in the pool calculator)
Click to expand...
First, may employment come soon! That's additional stresses that are not needed, anytime.

It sounds like you've got algae or something else organic using up your chlorine each day: the FC of 11 isn't enough to kill it, just keep it from growing fast, OR the the CYA numbers from the pool store are not right OR both.

Any way to take your water to another pool store for testing and see how they match up?

Otherwise, I think that you need to bring the pool to shock level: but that's based on the CYA reading, which may be 100 or may be 150...

Curious...What was the pool service using to sanitize your pool?
 
Hi,

Pool calculator says my shock level with CYA 100 is 25 PPM. The pool service used liquid chorine, imagine that, though I doubt he kept it at "pool calculator" levels, but water was always good. Wish I had done some testing when they maintained the pool. We did take a water sample to be tested 7 days after the pool service last treatment and FC was 3 and CYA of 70. Fortunately we kept a notebook of all the chemicals, amounts, etc that we added and when we realized why the CYA was going up I ran through the calculations of how much trichlor and dichlor we had added and I calculated that we would have raised our CYA 28 PPM and pool store testing is showing a 30PPM raise, so I think we are actually sitting right at 100CYA (70 PPM + 28PPM = approx 100PPM CYA).
 
pool4thekids said:
Hi,

Pool calculator says my shock level with CYA 100 is 25 PPM. The pool service used liquid chorine, imagine that, though I doubt he kept it at "pool calculator" levels, but water was always good. Wish I had done some testing when they maintained the pool. We did take a water sample to be tested 7 days after the pool service last treatment and FC was 3 and CYA of 70. Fortunately we kept a notebook of all the chemicals, amounts, etc that we added and when we realized why the CYA was going up I ran through the calculations of how much trichlor and dichlor we had added and I calculated that we would have raised our CYA 28 PPM and pool store testing is showing a 30PPM raise, so I think we are actually sitting right at 100CYA (70 PPM + 28PPM = approx 100PPM CYA).
Click to expand...

unless the pool service was coming every day they had to be using something else also. Tab's most likely.
 
No tablets were used, auto chlorinator was completely shut off. I believe pool service added enough liquid chlorine to spike up the FC. That combined with a high CYA allowed them to visit once a week. By the next week FC had dropped to about 2-3 PPM (as we verified by taking a water sample to pool store to be tested 1 week following their last treatment) at which time they would start the cycle over again.
Now according to Pool Calculator there were probably several days per week when our pool was below the recommended FC range of 8 - 13 but I think it wasn't dropping to 0 FC so nothing started growing before they were able to raise up the FC on their next visit. We have a light swimming load also, daily but only 2-4 kids. After trying the BBB method myself I am thinking that $60month may have been a bargain. I am spending more than that on Walmart Ultra. I am sure the pool service had a much cheaper source of the liquid chlorine also. I hate PB&J :(
 
Skip the 'algae killer'
Bleach (chlorine) is the best algae killer there is! :-D

Also, check your pool store or even wal-mart or the grocery stores... many times you can get 'liquid shock' which is just stronger bleach (10-12%) that is actually cheaper than buying 6% bleach.

And there is not really a savings if your CHILDREN are swimming in poorly sanitized water... Just because the water is clear/not green does NOT mean there is nothing growing! :shock: Algae is not the only thing that grows in pool water....
 
Welcome. :wave:

I understand your frustration.

If I may, I would suggest rather than spend the money on an entire kit, just order the FAS-DPD test, for around $25.00. Then you can determine if you have organics consuming your FC. You can continue if you like, testing your other numbers at the Pool Store.

Your method thus far of testing is not accurate enough. You can't wait an hour for testing at the pool store - it loses accuracy, and their results frankly aren't always accurate to begin with. Like test strips, the pool store tests are often calibrated to sell pool store chemicals, or they use strips and a computer reader...not good enough, or they are relying on inexperienced salespeople who don't even understand what they are testing.

Truly, I agree with the above, it sounds like you could have a "nascent" algae situation - meaning you are right on the fringe of cloudy/green water, but because you keep adding chlorine you are keeping it at bay, the algae is consuming the FC as you add it, which is why you are having to add more than you should. Very often this happens and there is clear water, just high chlorine demand. But if the FC were to drop too low it would be much worse than you are seeing. It doesn't take the FC dropping to 0 for a nascent situation to take hold, anytime it sits for several hours below the minimum FC for your CYA, you potentially can develop this problem. From your description, "there were several days per week when our pool was below the recommended FC range".

To determine organic consumption of FC, why we recommend an overnight test, and the only way to do it with any accuracy is the FAS-DPD.

Keeping the minimum when your CYA is 100 is very difficult. According to the CYA Chart, shock level would be 40- not very realistic considering how much chlorine that is. Is draining and refilling part of your water to lower the CYA not an option?

I think you would be much more satisfied with BBB if your CYA was around 50-60, and you maintained the corresponding levels.

If you do decide to purchase the FAS-DPD test, do the overnight test this way:

After sunset, test the FC, add bleach if necessary, wait 30 minutes and test again. Record the result.
In the morning before the sun hits the pool, test the FC again (and the CC) and compare the results. If you lose more than 1ppm, then you need to shock the pool. It would take a lot less chlorine to shock if your CYA were 60 rather than 100. :wink:
 
[A $80-$100 investment in a test kit did not seem logical.]

There are many reasons for testing the water yourself.

1.The health of your kids. You will get a feeling of satisfaction knowing that your pool is safe for your kids to swim in. You can kill algae but still have bacteria in the pool. One visit to a physician for an ear infection is one visit too many.
2.Pool stores tests are generally inaccurate. You will be adding the wrong chemicals at the wrong time. Your pool chemical expense will be too high.
3.Each time you have your water tested at the pool store they will try to sell you a chemical that you do not require. Pool stores love to scare pool owners into purchasing algaecides, phosphate removes, expensive forms of sanitizer, etc. You will save money by never going into a pool store. [We went to the pool store and bought (all the wrong) chemicals as recommended. ] Yes, and they will continue to provide expensive advice.
4.The TF100 test kit costs $68. If you keep your pool properly balanced you may have sufficient chemicals for two years. So your cost is $34 per year. A refill set costs $36. So that would be $18 per year after the first two years. I would expect that you will spend far more on gas going to the pool store.
5.Once you can do accurate testing you will reduce your spending on chemicals because you know, for the first time, the condition of your water. Our spring start up cost was less than one fourth of previous years because we used bleach, and only bleach, at shock levels to kill the algae.
6.[Do pool stores generally have enough accuracy to test for small overnight FC loses? ] In my opinion NO. But you can with a FAS-DPD Cl test that you do yourself.
7.Your costs will go down once you test the water yourself, understand the BBB method, and monitor your pool.

I also live in Texas and also have a 30,000 gallon pool. Last year we used BBB and we required 2 to 3 bottles of bleach a week. Our pool is in the shade part of the day so your sanitizing requirement could be higher.

Good luck with your pool. It is initially difficult to maintain your pool yourself. Much of the advice from the pool stores benefits their profits; you may have to unlearn their advice before you can learn how to properly maintain your pool. You will need a dose of POP (pool owner patience). If you read and learn you will have a safer, cleaner pool that costs less to maintain.

When your husband finds new employment (and he will) you will probably decide to maintain the pool yourself because you will realize that once a week maintenance is not sufficient for the health of YOUR kids.
 

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Usually in a pool that has 100 ppm CYA the chlorine will drop from around 14 ppm FC to 4 ppm FC over a week in intense sun such as in Arizona in the summer. There is a daily (24 hour) loss of 0.5 - 1 ppm FC independent of sunlight from oxidation of miscellaneous organics in the pool (including CYA itself) and then an additional loss from sunlight of perhaps 5% of the FC level (at 100 ppm CYA). If you are seeing more than that, then you have something else in the pool consuming chlorine or the test numbers (FC, CYA) aren't correct.

Your 30,000 gallon pool is large so will use more chlorine in absolute terms (i.e. 1 ppm FC is more chlorine at more cost in a large pool). Nevertheless, you should not be seeing 3-4 ppm FC drop over 24 hours starting at 10 ppm FC with 100 ppm CYA -- it should be more like a 2 ppm FC drop at the most. The overnight drop should be less than 1 ppm FC and probably a little less than 0.5 ppm FC (over 10 or so hours).

However, even if you were able to get your pool to 2 ppm FC per day chlorine usage, then that would still cost around $50-60 or so in chlorine so your $60 pool service was actually reasonably priced, especially if that included brushing the pool. Are you sure they only used chlorinating liquid or did they also use chlorine gas (i.e. have a hose in the water bubbling something in the deep end)? Do you know how much chlorine they added each week or what the FC was after they added chlorine? By any chance was the pool service Pool Chlor?

For a one-time cost addition to get to 50 ppm Borates, then you'll have extra protection against algae growth and this can not only lower the chlorine demand somewhat, but also may allow you to target a lower FC level, perhaps closer to 5% of the CYA level, but we don't have a lot of experience with this (yet).

Of course, if you were to use a pool cover, then you would substantially cut down your chlorine usage to less than 1 ppm FC per day which would clearly be less expensive than the pool service.

Richard
 
Thanks Richard for explaining the costs. I am in Austin, Texas and our pool service was not Pool Chlor. As far as I know they did not use chlorine gas (at least I never saw that). Our $60/month included only testing and chemicals (we had to do all the brushing :( but to tell you the truth not very often). They were literally here for less than 5 minutes per week. I think they make their profit during the winter months because even though we don't close our pools, temps are down and not much grows in the water at those lower temps, and service is still $60/month. We never tested the water until we shut off our service because we were not having any problems so I don't know what levels they were targeting.
We can partially drain and refill if you think we should target a lower CYA or we can be patient and let the backwashing take care of things over the next year or so.
What would a valid CYA target be for full sun/Southern TX. Any pool person I talk to here thinks the higher the better to a limit, they have no problem with 100-120 CYA. :roll:
Thank you!
 
I'd suggest targeting 60 or 70 and it will continue to drop with backwashing. My main concern is that if you confirm thru the FAS-DPD test an overnight loss of more than 1ppm, then you should shock and that means your current CYA being too high would require insane amount of jugs of chlorine to hold the shock at 40. So first confirm the overnight loss (buy the test! :wink: ) and then decide if you need to drain, or let it come down on it's own.

Do you cover? That really helps cut down on FC loss...
 
A couple of other suggestions would be, first, to make sure that you have cleaned your DE filter. If it accumulated too much junk, then chlorine is wasted on oxidizing things caught in the filter. Check your skimmer basket and pool pump basket as well. Also, if you get a lot of blown in pollen, then use a skimmer sock and clean it regularly. Pollen can also lead to a fairly high chlorine demand.

Given the experience of some others in hot sunny areas, I'd start with 80 ppm CYA and see how things go from there. Experiments Mark made show a rather dramatic increase in chlorine loss protection by CYA going from 45 ppm to 80 ppm though we don't know exactly where the biggest jump comes from, but anecdotal reports seem to indicate the greatest benefit is in the 70-80 ppm range. Of course as was pointed out, if you need to shock, then the higher CYA needs a higher FC level for shocking. Let's see what the overnight FC loss tells us.
 
A few years ago when I started at TFP I had a similarly high chlorine usage with crystal clear water. After going through the process of keeping the FC level at shock level until I had <.5 loss overnight I did see a decrease in chlorine consumption.

I have a swg now and only have to add 1 quart of muriatic acid per week, that's it. I live in Round Rock and probably have similar water quality as you do, though I don't know where in Austin you live.

The pool testkit is the best thing you can buy for your pool. It will save you more $$$ than it costs in chemical savings alone. When you know how much chemical to add, through testing you don't ever over dose. More importantly you don't let it get too low, allowing the algae to come back costing even more in getting it cleaned up than prevention.

Good luck with your pool
 
to lovingHDTV,

I am actually in Round Rock TX, but didn't think many would know where that is. Before you switched to SWG, do you remember what your "bleach" usage was, how big is your pool and your CYA? I have received a lot of good suggestions but don't want to spend $70 on a test kit if we are going to rehire our pool service in a month or so. From what Richard posted it seems our pool service was very fairly priced, especially if I have to add enough bleach to raise my FC level by 14 PPM/week (assuming loss of 2PPM FC/day).
 
First thing today, my husband is taking apart the DE filter and cleaning. We backwash regularly but as per Richard's suggestion we thought we should throughly clean it.

How does one install a skimmer sock out of a knee hi? Do you just stretch the knee hi over the top of the skimmer basket. We do get a huge amount of pollen :( so maybe a sock will help.
 
pool4thekids said:
to lovingHDTV,

I am actually in Round Rock TX, but didn't think many would know where that is. Before you switched to SWG, do you remember what your "bleach" usage was, how big is your pool and your CYA? I have received a lot of good suggestions but don't want to spend $70 on a test kit if we are going to rehire our pool service in a month or so. From what Richard posted it seems our pool service was very fairly priced, especially if I have to add enough bleach to raise my FC level by 14 PPM/week (assuming loss of 2PPM FC/day).
Click to expand...

Honestly I don't remember what my usage was. I only ran it that way for a month or so before upgrading to the SWCG. All I remember was that the usage went down significantly after getting it established and free of organics.
 
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