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inferno480

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Aug 5, 2012
21
Detroit, MI
So this is the 2nd year I've had an above ground vinyl 15' x 48" Intex pool (4440 Gal.), the first year I was able to maintain decent FC levels from the get-go by starting it with just bleach then occasionally adding some dichlor.

This year... different story. After opening it, I struggled a bit to keep FC at 3 or more, having to add a fair amount of chlorine every other day, but the pH was very stable and the water was crystal clear... until now. When levels would get low and I would add enough liquid chlorine to bring it to an FC of 6ppm, then the next day I would measure and the pH and FC were off the charts (FC readings of 8 or more). I was using the pool calculator and using all the correct amounts, however this year I am using 12.5% liquid chlorine instead of 6% bleach and di-chlor (like last year). When the readings were high (8+ FC), I wouldn't add any chlorine at that point, then I would test again the following day and it would be 0-1... finally I came to the conclusion that I obviously needed more stabilizer but still never thought much of it because everything seemed clean and crystal clear.

The pH readings have remained stable every day (7.4-7.6) and like I said the water remained clear until about two days ago... I noticed the water was a tad cloudy and green, and I started getting yellow "dirt" on the bottom surface. After I noticed the cloudy water I immediately sampled all chemical readings and they seemed OK except for low FC and CYA, which I am sure is the root of my problem...

pH 7.6
FC 1
CC 0
TA 80
CH 75-ish
CYA (less than 30, can't read lower)

I went to the local pool store and explained the situation (although I didn't mention algae since I was in denial about having an algae problem until today after doing more research), and they told me the dichlor I was using did not put stablizer or CYA into the water. (I am not even sure if that is technically possible or true, based on last year's experience) So I bought some CYA granules knowing that I for sure needed CYA and started floating them in a pair of tights tied near a return yesterday.

Anyway, today, I go outside to check the pool and see if the water looked any more clear (I added some chlroine last night [enough to get to 6 FC] and have been running the filter constantly), and it actually seems the same or slightly worse with the yellow stuff reforming on the bottom. Basically, I am unusure how to move forward from here... I kinda wish I had explored algae being my problem a day sooner, but there's no going back now. I am in a bit of a panic and was hoping somebody would have some advice... some thoughts/questions:

1) Leave the CYA granules in, since I know that it's needed? Problem is, I don't know my current CYA reading (aside from it being under 30, possibly even 0 since the granules will take a while to dissolve) and not sure when I'll be able to get a good reading. I also cannot backwash my filter for a week with these still dissolving. (I am using a mid-range Intex Sand filter instead of the cartridge filter I used last year)

2) Start shocking to kill the algae even while the CYA is still dissolving? Or maybe take out the CYA so I can get an effective shock in?

3) Use some sort of algaecide treatment? (I do have some Poly-30 on-hand...)

4) When should I start brushing/vacuuming? Some sources say to make sure not to stir it up, some say to start cleaning it daily?

Any help from the experts would be greatly appreciated to help this newbie through his first algae problem :)
 
The pool store is incorrect, only Cal-Hypo doesn't add CYA, Tri-Chlor and Di-Chlor do.
So long as the water in the test tube is cloudy when performing the test, you have CYA, even if it goes all the way to the top with a still visible dot, which makes it under 20-30ppm. Depending on which tube you have. You absolutely must test this outdoors, in the sun, with your back to it and the tube at waist level looking down into it.
See "extended test kit directions": extended-test-kit-directions-t25081.html

Re-test it this way and report the results.

How much CYA did you put in the sock? So long as you didn't pour it in the skimmer and It's truly in a sock by your return jet, you can backwash your filter. Only backwash when you reach a 25% pressure rise from clean. Also, each year you must clean and resettle the sand bed using the directions in my Sig.

CYA takes up to a week to show up in the test, but as soon as it dissolves out of the sock it becomes active and goes to work.

Assume your CYA is 30, or whatever you targeted it to, ie. how much you added in the sock. Then start the shock process, read all about it in the link on the last line of my Sig.
So if your test tube only goes up to 30, but you could still see the dot when filled all the way to the top of the test tube, and you added enough CYA powder to bring it up by 10ppm. Then assume you have 30ppm CYA. But that's a bit of an educated guess. It would be more accurate to know how much Di-Chlor as well as how many pucks you have used since you filled it. Poolcalculator can figure this out for you by using the: "Effects of adding chemicals" function at the bottom. Once you have filled in your pool volume in gallons that is.

Yes, the problem is you don't have enough CYA in thee, thus you are loosing too much CL to the sun's UV rays not consistently leaving enough FC to keep the water clean and sanitized.
This is assuming you have correctly performed the CYA test as noted above.
The yellow stuff you describe is likely just pollen. Mustard algae only really grows in shaded areas.


Edit: Please fill in your signature and location info in your profile as instructed in the 1st link in pool school. This way we can better assist you based on your climate and equipment.
See my Sig for link.
 
Wow guys, thanks for the quick reponses... sorry about that, my sig & location have been updated.

I use a Taylor FAS-DPD kit; thanks for the links to the enhanced instructions on the CYA readings, that's basically what I've been doing. It is still somewhat cloudy, but was definitely below 30. Thanks for confirming the suspicion on the pool store's answer as well.

I just re-checked pH, FC, and CYA today and here is what I have:

pH 7.8
FC 1
CYA (still less than 30)

I put 1 lb. of CYA granules in the sock. The instructions state that you need 3 lb. per 10,000 gallons of water to achieve 35 ppm CYA. So right now I have 1 lb. floating near the return (not in the skimmer) of a 4,440 gal. pool. I'm pretty sure I have low CYA, because less than 24 hours ago I added ~20 oz. of 12.5% liquid chlorine because I was only at about 1 FC then, and it wasn't even very sunny today.

I only did five or so applications of dichlor back when I first started the pool (around Memorial Day), using the Pool Calculator and the Seasonal Pool Start-up Guide it said to add about 6-6.5 oz. of dichlor for four days in a row and I believe I did five. I've been using (a LOT) of 12.5% liquid chlorine since, but there have been many peaks and valleys with the FC numbers (whereas last year it was easier to maintain an FC of 3-6).

Alright, I guess I will go ahead and start shocking towards a CYA of 30, leaving the sock w/the CYA near the return. I am a little puzzled on how the pH jumped up to 7.8; should I worry about trying to lower it back down to 7.2-ish before beginning to shock with some muratic acid, or will the CYA dissolving be sufficient to get the pH down?
 
30 to 32.5oz of Di-Chlor would have raised your CYA by 26-28ppm. Assuming no other sources of stabilized chlorine and you started from a fresh fill this year.
That 1lb of CYA powder in the sock will raise it by 27ppm.

Assuming your pool really is 4400 gal, as I think it may be a bit more, since a 15ft pool would have to be filled to a depth of only 3.3ft to achieve that volume of water. Which is pretty low.

To be on the safe side, unless you have had a lot of overflow due to; rain water, massive splash out and topping off with the hose, or lots of backwashing. I'd only let about half of that sock dissolve and then pull it out and wait till the newly added cya registers. Give it 4 days and test again, a full 7 days is advised to save on reagent.

I'm betting that maybe last year you had the cartridge filter, thus no backwashing and thus year the sand filter upgrade. Is that right? If so, that would account for the CYA loss over last year, from the backwashing.

Remember, CYA is easy to add, drain to remove.
So if it's still a bit low, you can always put the sock back in again. Don't forget to squeeze. :mrgreen:

You're doin' good, hang in there! :goodjob:
 
Update: Good news!

Been shocking by maintaining 10-12 PPM FC 2x per day and it's working great. I removed the CYA sock for now (will test CYA next week). The water is much less cloudy and is back to being clear in color. Less yellow stuff accumulating on the bottom as well (been brushing it daily). Filter has been running 24x7 since this started last week, not really enough pressure for a backwash yet still (so I haven't).

Question... the water is still slightly cloudy, which is to be expected since I've read that this could be because the dead algae is grey and may take a week or so to be completely filtered. Am I OK at this point relaxing things back to 6ppm FC and swimming in the water, or should I keep shocking until everything is completely clear? (would prefer not to waste all that liquid chlorine if I don't need to, plus I want to swim!)

pH still seems to be within normal range, at 7.6 today. I didn't add anything to reduce the pH, maybe things leveled-off as a side effect from adding the CYA.
 
There are 3 criteria for ending the shock process: <.5 ppm CC, <1 ppm FC loss overnight, and the water is clear. Since you say the water is still cloudy, that means you have not finished the shock process yet. As for swimming, it is safe to swim if the FC>minimum and FC<shock level. Have you considered adding DE to your sand filter to speed up the clearing?
 
Haven't considered adding DE... tough to find it locally in < 25lb packs. But I am alright with continuing to shock and run the filter for a little while longer -- I just want to be able to swim on days like today. The main issue is that I don't really know how much CYA I have right now, and may not know for another week. I'm assuming it's around 30ppm, perhaps a little more. FC right now is at 9, which is above minimum and slightly below shock for the CYA I originally had; however, at the same time as shocking I've been adding CYA, so it's a bit confusing. I don't have any CC (never have), and I am probably very close to the < 1 ppm FC loss overnight. I would say the water is about 90%-95% clearer than it was, but not quite 100% yet. Since I know I have "some" CYA now, I am thinking I might shock up to 12 or 15ppm "just to be sure" (but I won't swim in it once I do that). I just don't want to jeopardize efforts so far or risk giving myself chemical burns, but everything I've read said < 10ppm should be fine to swim in and that's with no CYA.
 

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You might try the pool stores & see if they have Cellulose Fiber, a DE Alternative made from wood pulp.
It comes in smaller bags, you can also buy it on Amazon pretty easy too. Prepare to get some.. HUHs??? from the PS people.
At least I did, as many had no idea what it was. LOL :hammer:

For CYA, simply go with 30ppm if that's what you approximate you have now, based on what you have added since. Shock level for a CYA of 30ppm is 12ppm FC.
There's a bit of leeway room, so swim away!!
It's best not to stop the shock process as you'll lose any ground you have gained and have to start all over when you do SLAM it again.
Make absolutely sure you keep it @ or above 12ppm FC, test it more than 2x per day... that is until you get the idea that it's not eating as much. Run your filter 24x7, only backwash when the pressure rises to 20-25% above your starting clean pressure. Backwash too often and the filter cleans poorly, too little and... well.... same thing, except circulation suffers and can overwork your pump motor. I wouldn't vacuum to waste having such a small pool, I'd just vacuum to filter. Start with a bit of a dirty filter, since it filters better as it cakes up a bit.

One thing to consider are these: http://www.dudadiesel.com/search.php?query=filter+bag
They're cost effective substitutes for Slime-Bags.
You can use them on your backwash line to send the water right back into your pool, only filtered, leaving the junk in the bag. This way you save on chemicals & the constant Yo-Yo!! of CYA adjustment.
Maybe use a 25 micron bag inside of a 5, 10, or even 1 micron bag. That way all the bigger stuff from the sand filter that gets blasted out during the backwash will trap in the larger micron bag, not clogging up the smaller micron bag so quickly. Primarily for faster flow as well as efficiency of the bag's filtration.

Here's a thread on it: slimebag-for-1-10-of-the-price-yes-you-can-t32951.html
They're cheapest @ Duda Diesel, I compared them last season.
I haven't bought any yet, but I will be doing so.... very, very soon if not maybe this week.

For some perspective....
At 10ppm FC in a pool /w a CYA of 30ppm, your total HOCl (hypochlorous acid) Cl2 IE. the active sanitizing chlorine is only 0.213ppm Cl2. Even @ 20ppm FC it's only 0.883ppm Cl2.
If you compare that to your tap water /w 0 "ZERO" CYA in it @ 3ppm FC you have 1.451ppm Cl2.

So 0.213-0.883ppm Cl2 while shocking, vs. 1.451ppm Cl2 in your tap water.
See how safe it is? Yeah you might get some whiffs of chloramines from the biodegrading bio matter, but it's fine.

PS. Chemical burns don't really happen from CL in pools. What does happen is skin irritation/rash from the chloramines, that's that nasty smell of a public pool. A small amount of chloramines usually won't do it, it has to be a pretty high PPM of CCs to affect most people. Keep in mind the sun burns of CCs while shocking. Skin irritation can also happen from incorrect pH on sensitive skin. You can also get bacterial infections from improperly sanitized pools.
 
I used a filter additive (forgot which one) that my PS carried and it did the trick. I had a slight off color in the deep end that I tried to convince myself was my imagination as I wanted to stop the shock process because all the other criteria was met. I filtered and maintained shock levels for a couple days with no improvement. I added the booster and bam, the water became crystal clear. Now I know what crystal clear looks like. Its been that way ever since. Good luck
 
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