Oh where oh where has my chlorine level gone?

[tim_pool_newbie]

I see others have posted similar issues with a very high chlorine demand, but wanted to post my own message with my own specific levels and such as I understand each pool situation is different. Let me give you the facts, and hopefully someone will see something that isn't right and make a recommendation for me.

I have a brand new plaster pool (22,500 gal) and I'm a semi-recent convert to the BBB method. In previous posts I have explained how I used the pucks and granules for the first month the new pool was in operation, but since then (end of June) have been religiously following the BBB method - mostly just adding chlorine (and a bit of baking soda twice to raise alkalinity and some calcium chloride recently to raise CH a bit).

My pH is very consistent at 7.6 (maybe 7.5 - not sure I'm interpreting the color correctly). In fact, I never even got a the huge spike in pH the PB said I would at startup, and so I've still got lots of pH Down on the shelf.

My CYA level is 60 (explainable based on the calculation of the amount of CYA introduced from the pucks and granules I was formerly using).

Based on this, I've been targeting FC of 7 and adding at least a gallon or so of 6% WalMart bleach daily - following amounts based on PoolCalculator.

I can also confirm that I've never gone over 0.5 CC in any given day, and most days it registers zero.

Living in a new development, there are no trees to speak of in the immediate vicinity of the pool and so it gets a full day of sunlight, with temperatures here averaging in the 80's (pool temp usually 85).

Last night at 7pm I measured my FC at 4, so added 140 oz of bleach to raise it to 7. At 10pm I measured again and was glad to see it was right on the money at 7. This morning at 9:30 (sun had already been up for a little while) I measured FC at 4.5 with .5 CC (no CC at all on yesterday's testing). Tonight at 6pm I measured yet again and got an FC of 2.5 and .5 CC.

Is it really possible for the sun to be using up THAT MUCH of my chlorine on a daily basis? There's been NOBODY in it during any of this time (usually only used on weekends).

So to provide the full picture, here are all of my current levels as of just now:

FC - 2.5
CC - 0.5
TC - 3.0
pH - 7.6
TA - 80 (very consistent)
CH - 210 (was 180 about two weeks ago but brought it up to 250 and it's been that way till this new test today)
CYA - 60 (I'm still a bit inconsistent with my CYA testing, but it's usually between 50-60)
Temp - 86

I'm adding 210 oz bleach right now to boost again to 7.

Any other suggestions? I'm seriously contemplating a SWG or Liquidator as the jugs are getting really old - can't keep enough of it on hand.

Thanks,
Tim

P.S. Otherwise, the pool has been crystal clear since the day they filled it and have never seen algae or had any other major issues.

 

[svenpup]

You should do a good overnight chlorine loss test. Measure after dark at least an hour after adding and then again before the sun comes up.

I suspect that you have a low level algae bloom trying to take hold.

I do not like the way the CYA/Chlorine chart specifies the "target" level. It isn't high enough over the minimum to ensure that the FC NEVER falls below minimum. If your daily FC demand is more than 2ppm (which is very likely), than targeting 7 means that you are guaranteed to fall below your minimum of 5 before you add chlorine again. This opens the door to algae.

If you fail the overnight test then you should shock. It should be easy because it hasn't gotten out of hand yet. After that you should find that you daily FC loss is less.

You should always add enough chlorine to ensure that you never fall below minimum, so if your daily FC loss is 3 and you have a CYA of 60 you should target at least 8, and probably 9 to be safe.

 

[Beez]

It sounds to me like you are dealing with a nascent algae bloom. The sure way to find out is to perform the Overnight FC Loss Test.

As for your chlorine demand, if you started this morning with 4.5 and ended with 2.5, that's only 2ppm which is normal. Maybe I'm not understanding though?

EDIT: svenpup typed faster!

 

[svenpup]

...and looooonger

 

[Beez]

...and looooonger

sure, rub it in...

 

[tim_pool_newbie]

Thanks for the responses. Beez, you are correct that I only had an FC loss of 2ppm today, however, I added my bleach last night and confirmed a bit later that my FC was at 7. So I also had a 2.5ppm loss overnight PLUS the additional 2ppm loss throughout today....for a total loss of 4.5 ppm since my last addition of bleach. And it's been pretty much this way for the past 2 months when I started the BBB method....a very high chlorine demand each day.

Is it possible that a nascent algae bloom could really linger that long without ever showing up....always on the verge of breakout but never doing so??

 

[duraleigh]

Hey, Tim,

Go back to the basic premise that chlorine only gets consumed by two things....sunlight and organics. The overnight FC loss test eliminates the sun so it will either prove or disprove the presence of organics.

 

[Beez]

I would perform an overnight FC lost test again tonight, and be sure to follow the instructions carefully as your result will determine whether you shock or not. If you show a FC loss you will need to shock according to the instructions in Pool School.

Your results up to this point are a little confusing, because if you had a nascent algae problem I would have thought your daily FC loss would have been considerably higher than 2ppm. But you also are saying you are losing that much overnight as well...

There is no reason you can't get your pool under control. Just exercise a little patience and diligence with the protocol. You will get there!

 

[tim_pool_newbie]

@Duraleigh - it's funny you should post about "going back to basics". I was thinking after posting my original message how I felt like I was looking for some "magic" answer for my pool, and yet when I read all the other posts on this forum I find myself thinking "looking at your test results, I can clearly see what the issue is and the solution is X". I guess when it's personal, you tend not to see it the same way!!

So I went back to basics and agree completely that with the constant overnight loss I'm experiencing, there must be some type of algae outbreak preparing to attack. In the interest of time (I have folks coming for the weekend and am going out of town all next week so need to get the pool on auto-pilot for the person covering my daily duties with the pool), I decided to forego the overnight FC loss test and simply go for shocking the pool last night. I felt confident with my earlier test that there was definitely an overnight FC loss happening.

So I shocked to FC of 24 last night (actually about an extra quart of bleach than was required). The water immediately became cloudy and stayed cloudy all night long (I always see some cloudiness when adding bleach, but it usually goes away in a few minutes). So today I'm staring at a VERY cloudy pool. Will this go away throughout the day today?

Meanwhile, I had seen that my DE filter pressure was starting to rise a bit and figured by Saturday I would need to do a backwash (normal pressure of 20 was now around 25). But after I added the chlorine I noticed the pressure jumped practically to 30 (the point at which I know a backwash is overdue). This morning the pressure has dropped down slightly to 28, but definitely due for a backwash. I guess the upcoming need for a backwash could also contribute to the original issue of a nascent algae bloom, huh?

So I'm wondering, should I let the bleach for the shock sit for a while and do its thing, or should I go ahead and backwash now, knowing I'll lose some of this bleach in the process? I'm seeing this as sort of a "chicken or the egg" kind of thing!!

Thanks in advance for everyone's advice.

Tim

 

[duraleigh]

Hi, Tim,

1. Keep your FC up @24 until your pool is crystal clear....may take a while. Have you read "How to shock your pool" up in pool school? It requires the FC to be HELD AT SHOCK LEVEL until.....
1. Your pool water is sparkling
2. Your CC's are .5ppm or less
3. You can hold your FC overnight without losing more than 1ppm.

You absolutely need to backwash. When you perform the shock process, it's about killing and then cleaning. The chlorine does the killing part, you and your filter must do the cleaning.

So, backwash, whenever your psi calls for it...don't worry about the little FC loss, brush and vacuum the pool to help the filter get out all the dead organics and anything else.

I am puzzled by the cloudiness. There is a very temporary change in pH when you add FC but I don't see anything in your other test results that would cause cloudiness. Have you added any other chemistry to the pool in the last 2-3 weeks?

 

[frustratedpoolmom]

I would backwash, test your level, raise it up to shock again. You don't list TA in your results but this could have something to do with the TA/CH and raising the FC up to shock.

I do agree this was a nascent algae issue and the filter pressure rise would tend to confirm that...

 

[tim_pool_newbie]

Yes, I have read just about every article on this forum, but I'll re-read the stuff on how to shock the pool. Funny thing is, my pool HAS BEEN sparkling up until last night when I added all that chlorine!!

Hopefully after the backwash, this will go away.

Speaking of backwashing - with a DE filter, is it common practice to open the filter and hose down the grids during a routine backwash? The startup company told me this was not necessary and that they'd do it once a year for me when they come to close the pool (of course being presumptuous on their part that I'd even have them service my pool!!). I've backwashed about 3-4 times now since the pool's opened this year and have never cracked open the actual DE filter to clean the grids.

I just completed a backwash though and typically I thought I see my pressure way below normal until I get the new DE powder put in. This time, the pressure came back immediately to 20 (normal pressure). I still have it off and haven't added the new DE powder yet (came inside first to write this post). Do you think I should pull out the grids and hose them down first? I've never done this, so not sure really what I'm in for.

 

[duraleigh]

Sorry, Tim, I have a sand filter and am of very limited help on DE. Others will comment.

Back to your cloudiness. It's pretty safe to say that chlorine (bleach) does not cause cloudiness by itself. It is reacting with something in your pool. Finding out what that something is will probably tell us what to do about it. Anything you can remember putting in your pool other than what we've discussed?

 

[dmanb2b]

You do not need to take apart the filter each time you backwash...that's good annual maint.

From pool school:

DE filters come in 2 varieties, the first makes use of a multiport for the cleaning and the procedure is exactly the same as cleaning a sand filter. The only difference is that the DE is removed with the dirt and therefore you have to add more after cleaning the filter (sand is not removed when backwashing, so doesn't need to be replaced). Because the backwashing doesn't remove all of the DE only add ~80% of what the filter calls for when new or fully clean so that the filter doesn't clog with clean DE.

The other kind of DE filter utilizes a handle on top of the filter to shift the internal assembly up and down to reduce the rise in pressure and is known as a "bump filter". To recharge the DE, turn off the pump and open the air valve on the top for ~5 seconds and recluse it. Now slowly push the handle down and quickly raise it up 5 times. Restart the pump and check to see that the psi dropped more than 2. If it did, you're all set and you don't need to add any new DE to the filter. If it didn't, repeat the bumping procedure, remove the plug from the bottom of the filter and run the pump another 30 seconds. Replace the plug, open the air valve on top and run the pump until water is coming out of the air valve. Do this whole process twice and you'll be all set to add ~80% of what the filter calls for when new, just like the other type of DE filter.

 

[tim_pool_newbie]

Thanks...I feel like I've got some of you on speed dial (hmmm maybe I should!!). After my last post, I went back and read some articles again, including the one that dmanb2b just referenced re: DE filter maintenance. I do not have the bump filter type, so I guess it's just the standard grid type. Based on the article it describes how algae and other materials can eventually clog the filter grids - thus the annual or semi-annual maintenance. I wonder if perhaps this is where my algae issue is (hmmm??)...since I'm not actually seeing anything IN the pool.

As for other recent chemical additives, I've been keeping pretty good records lately, so other than bleach almost every single day, the only other things I've added lately are:

7/16 - 1/2 qt Algaecide (had been adding this every 2 weeks per startup company, but stopped after this based on recent posts)
7/23 - 15lb Calcium Chloride
7/23 - 11oz PoolPerfect
7/30 - 11oz PoolPerfect (was starting to use this weekly based on package instructions but now am just going to use it when I have heavy bather load with lots of suntan oils)

That's it.

I suspect the cloudiness will go away once I get the filter running again with new DE powder. But at this point now I don't know how much DE to add since it already seems to be at almost the correct pressure level before I even added in any new DE.

 

[Beez]

Are you saying you backwashed without recharging with DE immediately after? Not so good as I understand it...

Also, you're saying your "clean" filter pressure is normally 20psi? That seems high to me...

What size/type filter is it? There should be a label on it with this info. It sounds to me like you do need to open and inspect the grids, but wait until your pool clears up first.

 

[tim_pool_newbie]

Sorry if I wasn't clear in my original posts.

After I backwashed I turned the filter on to go add the DE powder and immediately noticed the pressure was already back up to 20. So I shut it all off and came inside to write these posts. So no, I haven't been running the filter without any DE in it - other than a few seconds after the backwash.

As for size, it's a Jandy Model #DEV60. The label says this:

Effective filtration area - 60 sq ft
Design Flow Rate: Residential - 150 gpm
Required amount of DE - 6lbs
Maximum working pressure - 50 psi

Yes, 20 psi is normal for me on this filter...and I backwash at 30.

But all of this may be a moot point. I went ahead and started adding the DE powder and watched to see if the psi would raise even more. It did not!! So I'm still holding steady at 20 psi (normal pressure) with all the DE in place.

And I also noticed that the cloudiness is starting to go away. I have a feeling by the time the sun eats away at it for a while today, it will all clear up nicely and we'll be swimming in it all weekend!!!

But I'll definitely be keeping an eye on it!

 

[tim_pool_newbie]

OK, I wanted to post a message saying that I'm out of the woods on this issue, but I'm not so sure quite yet. Shortly after backwashing, the cloudiness started to go away and now (a few hours later) the water is really looking nice and back to being crystal clear!! BUT, I just did another FC test and it seems to have gone from 23.5 @ 7:30am to 10 @ 2:30pm (a loss of 13.5 in 6 hours). Is it common for shock FC levels to dissipate so quickly? Oh, and my CC level is at ZERO!

I'll do an overnight FC loss test tonight, but should I continue to raise to shock level (24) for the rest of the day?

 

[Beez]

For the shock to be effective you need to bring the FC up to shock level and hold it there until you have .5 or less loss overnight. Otherwise you are wasting $ in bleach.

 

[dmanb2b]

That is a lot of FC loss by mid day, but given CC is zero and water is clearing quickly, you can try the overnight and if you do not pass, continue shocking. What is your CYA level again?

The high FC would have killed any algae inside your filter as well, so unless the grids are clogged, I think you are OK on that front.