CYA goes away...

[davelinde]

I have a couple of questions. Did you fertilizer your yard recently? Have you had heavy rains? Does your pool have and auto filler and an overflow pipe? Did you have a swampy pool at start of swim season?

Yard is fertilized on a bi-monthly schedule by the service, and DW mentioned something about "phosphates" the other day - relevant?
It's Florida, define "heavy" (uh yes)
No autofill - I fill manually added about 2" last month when it to near the bottom of the skimmer - it has not lost more than 3/4" since then.
We swim year 'round but no... it has been clear since the first day we filled it - never, ever, a swamp at all.

 

[zea3]

Heavy rain or a lot of frequent rain can put enough fresh water in the pool in a short period of time to dilute the CYA, same as a partial drain/refill cycle lowers CYA. If you have had several inches of rain over a months time and did not add more CYA that could account for some of the lower CYA level. Bacteria from soil can be in the run off rain water and will increase FC demand. Recently applied fertilizer can also enter the pool in rainwater run off, increasing FC demand and dropping FC to 0 very quickly. This can allow the bacteria to grow and consume the CYA leaving an ammonia by product. I don't know if this has happened in your pool but you can purchase an ammonia test where aquarium supplies are sold. The test is inexpensive and I don't think pool stores test for ammonia. If you do have ammonia you will need to SLAM the pool to clear it.

 

[davelinde]

Our pool deck is pitched away from the water and the screen enclosure perimeter makes a good curbing to the adjacent landscape/lawn. I would think run-off into the pool would be unlikely. The lawn service does do all liquid application though, so overspray could surely get in the pool.

DW added CYA and the FC bounced right back up immediately...

 

[davelinde]

So... (and feel free to say I told you so) somehow our CYA has gone from 30 to 80 and FC has dropped. I went and looked and found some algae growing in the flange of a bubbler. DW has agreed the right thing to do is slam the pool... but he pool guy told her that 10ppm FC loss over night "can happen with evaporation". I thought that over night there was only oxidation loss from organics?

In any case... I convinced her to get the FC back up to target level asap. I went a re-read some pool school stuff about algae and slamming but I can't find the parts where I thought I'd understood that FC loss was due to a photo-reaction and the organics?

 

[Smykowski]

So... (and feel free to say I told you so)

No worries....no one here will ever gloat.

but he pool guy told her that 10ppm FC loss over night "can happen with evaporation".

HA! That's a new one. We'll have to tuck that one away somewhere.

I went a re-read some pool school stuff about algae and slamming but I can't find the parts where I thought I'd understood that FC loss was due to a photo-reaction and the organics?

There are only two things that consume FC:
1. Sunlight. The chemical bond is such a weak bond that UV radiation will break it up.
2. Organics. In this case, the FC is doing what it's supposed to and killing algae/bacteria/etc. in your pool. (Technically it doesn't have to be organics. Ammonia/urea/other nitrogen based compounds can be oxidized by FC. Either way the FC is doing it's job and getting the "yuck" out of your pool.)

SLAMing the pool throws a large, sustained amount of FC at algae so that you have an algae kill rate that is faster than the algae growth rate. The overnight chlorine loss test (OCLT) is done at the end of the process to ensure there is no algae left in the pool. Remember, only two things use up FC. By doing the test at night, you're eliminating one of them so that you can test for the other.

 

[davelinde]

There are only two things that consume FC:
1. Sunlight. The chemical bond is such a weak bond that UV radiation will break it up.

That was what I thought... well, actually, I wasn't sure what it was about sunlight that did what - but I figured the point of OCLT was the no sun part and if there was some kind of evaporation loss, having no sun would not matter.

 

[jblizzle]

There is no such thing as evaporation loss. Get a new pool guy or take over for yourself.

 

[davelinde]

So this morning I found out that my wife is not exactly sold on the idea of SLAMing or shocking.
She does seem to like the idea of taking water to a pool store, getting a "free" test and then just doing what they say... (which so far has been... add CYA, add Chlorine, add salt - not actually crazy)

I am not going to fall into these traps though.... either of just doing what the pool guy says or getting more hands on myself and ending up being the one who is maintaining the pool.

My wife WILL be won over with information and results. So two questions for our situation...

first, DW says she never measures any consumed chlorine even after a lot of chlorine has "gone away"... which is why she still tends to believe the pool guy idea that it is "evaporating". Is it possible to lose 10ppm FC in 12 hours and still measure no CC? Test error?

next, the visible algae in the bubbler looks to be getting worse I am guessing I need to disassemble the eyeball thing to get under the flange and physically remove the algae? Any advice on how to do that? Is it possible that dislodging it will make things worse by spreading it around more? It is under 9" of water so I can get to it but can't easily contain whatever I brush away...

 

[Leebo]

first, DW says she never measures any consumed chlorine even after a lot of chlorine has "gone away"... which is why she still tends to believe the pool guy idea that it is "evaporating". Is it possible to lose 10ppm FC in 12 hours and still measure no CC? Test error?

It is in theory possible to have that large of a drop.....but HIGHLY unlikely. About the only way you can is if you wait some time between testing, and there is no chlorine in the pool. Again, there is NO way it evaporated overnight......algae is consuming it! Normally, your test results will show something growing in the water before your eye can see it. The fact you're able to see the algae growing is a cause for a SLAM session. For us to really help you out fully a full set of YOUR test numbers will be your best bet. I'd suspect a testing error in this case however. Take a quick look at TF-100's YouTube Channel for a video on how to preform the test. I'd be SHOCKED if you can have that drop with no CC's showing up.

next, the visible algae in the bubbler looks to be getting worse I am guessing I need to disassemble the eyeball thing to get under the flange and physically remove the algae? Any advice on how to do that? Is it possible that dislodging it will make things worse by spreading it around more? It is under 9" of water so I can get to it but can't easily contain whatever I brush away...

Once you start to SLAM your pool the chlorine will start to kill off this algae. Brushing the spot the best you can will help the process out, but if you're unable to get to it, the chlorine will in time kill it off. The largest key however is keeping enough chlorine in the water to allow it to kill any algae faster than it can grow. At the rate you seem to be going, I'd guess your water will be green here shortly.

Lose the pool guy......he's not knowledgeable enough to give you accurate info. Post full test results from YOUR TF-100, and we'll get you on your way.

 

[Smykowski]

Can't answer the second question, but I can answer the first...

When battling algae it is very common to see 0 combined chlorine throughout the process. Combined chlorine is another name for chloramines. Chloramines are the byproduct of free chloring oxidizing (breaking up) nitrogen based compounds like ammonia, sweat, pee, the film from sunscreens, etc.

On the other hand, FC kills algae because the algae thinks it is water. When it is ingested into the algae, it kills it from the inside. All that's left is algae carcasses - no chloramines. If you have algae but no nitrogen compounds in the water, you will very likely see 0 CC at all.

Have you looked at some of the threads in "Defeating Algae." There are lots of success stories with pictures from start to finish so you can see how it works. I'm on tapatalk right now, but when I get home in a bit I'll try to find some good ones.

 

[duraleigh]

So this morning I found out that my wife is not exactly sold on the idea of SLAMing or shocking.

Two pool water managers with different philosophies is a recipe for trouble.

Your wife should either come on the forum and learn what we teach or continue to go to the pool store and do what they say.....either way she prefers.

As an alternative, you could take over the pool chemistry management and choose the path you feel comfortable with.

Blending Pool Store testing and advice is almost never compatible with the principles taught on this forum.....you end up caught in the middle.

 

[davelinde]

I just took a look in the log book for the pool and found
FC 26.5
CC 0
Ph 7.2
TA 100
CH not tested
CYA 80

and I know DW added chlorine to get above 30ppm before she left today and we'll check/adjust it again in a few hours.

Thanks for the info on CC measure. The water is a bit cold so there is little or no swimmer loading, I'm thinking this is consistent with 0CC and an algae bloom in progress.

Yep - I'm caught in the middle.

 

[Leebo]

When were the walls last brushed?

 

[davelinde]

When were the walls last brushed?

yesterday, maybe Sunday. I remember seeing my wife dragging my son out there to do it.

 

[timerguy]

There are only two things that consume FC:
1. Sunlight. The chemical bond is such a weak bond that UV radiation will break it up.
2. Organics. In this case, the FC is doing what it's supposed to and killing algae/bacteria/etc. in your pool. (Technically it doesn't have to be organics. Ammonia/urea/other nitrogen based compounds can be oxidized by FC. Either way the FC is doing it's job and getting the "yuck" out of your pool.)

SLAMing the pool throws a large, sustained amount of FC at algae so that you have an algae kill rate that is faster than the algae growth rate. The overnight chlorine loss test (OCLT) is done at the end of the process to ensure there is no algae left in the pool. Remember, only two things use up FC. By doing the test at night, you're eliminating one of them so that you can test for the other.

Last spring, after a year of continuing the previous owner's pool maint regimen of chlorinating the pool using trichlor pucks and shocking weekly using dichlor granules, and having local hw store testing the water for "free". Read-- selling expensive chems to fix any problems they discovered. I started going to leslies who convinced me my recurrent algae problems would be best treated by using phosfree and algecidea-- the whole time telling me my cya was 40 ppm and my hardness needed a major increase. Then, I finally got Involved in this forum and learned the bbb way of maintaining my pool. I bought the Taylor tester recommended and found my cya to be over 340!!! Yes, my cya disappeared-- after draining 8,000 gals out my pool 5 times, which overshot the 50ppm I was aiming for by 25ppm. I hadn't used my test kit properly and wasn't getting accurate results. I happened to have some trichlor pucks that I used to get it back up to 50ppm again. Since then, I have stopped using anything but 8.25% bleach. My pool is the prettiest blue color I have ever seen it. I have never let the fc to get below 1ppm and since my water temp has gotten very low, I havent used hardly any chlotine at all. The last time I poured a 121oz jug of bleach into my pool was over a week ago, and this morning my test results were:
Fc-- 2.5
Ta--100
Ph-- 7.8
Ch-- 80
Cya--60 I have no idea how that increased??? If anything, with the recent rains, I thought it would have decreased.
Water temp is 45º
The chlorine levels have been this way for a couple months now. (Hardly any usage) -- During the summer, I was typically adding a jug daily. I'm considering using cal hypo tabs this summer which I have calculated to be a cost effective replacement for bleach. I'm receptive to any thoughts from the experts.
One thing for sure, leslies will never see a water sample of mine again!

 

[jblizzle]

@timerguy:
First, the CYA test can be sensitive to water temperature, did you let it warm up? It is also sensitive to lighting, so I would not read too much into a 10ppm difference.

Second, you are keeping your FC dangerously low. The FC/CYA Chart shows that you should be keeping your FC above 4-5ppm at all times .... 2.5ppm is too low and certainly letting it drop to 1ppm is a bad idea.

If you want to discuss further, please start your own thread.

 

[davelinde]

OK... so 5 weeks later and this is starting again.
We use the pool store to check our salt levels monthly (again, DW likes "free" a lot) and the salt level is fine, but AGAIN the CYA has somehow dropped from 80 to 40 in 5 weeks. DW bought more CYA again and wants to add it tomorrow.

In the last month we had maybe 2" of evaporation loss that I topped off with city water, and after I did that we had about 2" of rain. We added a solar cover when it got cold and the water level has been holding steady (though quite high) for the last week. From what I've read... I can't get my head around a 50% drop in CYA level in barely a month and have to think there is a measurement error here somehow?

 

[jblizzle]

That does not make sense.
Who is testing the CYA?
Are you (or wife) doing the test correctly? Outside with back to sun and tube at waist level?

 

[Patrick_B]

I wouldn't trust the pool store Cya number if it were me. I would get my own kit, test it myself, and adjust based on it alone. "Free" is often worth exactly what you paid for it. You could say the same about our advice, but time and again we find that Cya is one of the most often wrong numbers from the pool store.

As Dave mentioned above, if you continue mixing advice, you'll get mixed results. I know you are willing to try what we suggest, but you have to get your wife on the same page or this roller coaster will continue. As suggested, why don't you try getting your wife aboard with what we teach, or convince her to let you take it for a while?

 

[davelinde]

..why don't you try getting your wife aboard with what we teach, or convince her to let you take it for a while?

I'm trying. She eventually responds well to fact, and especially economic arguments.

I'm resisting the "oh just let me do it"... since I can't see it going back it I ever start.