Drain This Puppy?

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J

Jaywalker

0
Dec 4, 2009
101
San Antonio, Texas
Surface
Plaster
Chlorine
Liquid Chlorine
Here are my numbers as of 20 minutes ago:

FC = 0
TC = 3 (This has dropped from >5 yesterday since I added the 5 pounds of ChlorBrite.)
pH = 6.8 (Down from 7.2 since yesterday.)
TA = 70 (Down from 80 since yesterday.)
CH = 470 (First measurement.)
CYA = 120 (to 210) Both interpolated, as the scale only goes to 100. It's certainly greater than 100.
It's a big observational swing, but I'm still working on the testing procedures. At 210 I was unable to see the edges of the black dot against light floor in a dim room, but we could see the bottom was dark. At 120 I was unable to see any dark at all in the bottom of the tube against our concrete apron outside in the light. We performed this test six times, as there was plenty of reagent remaining in the squeeze bottle for two complete tests for each of three refillings. Leslie's automated run gave us a "40" reading three days ago.

The trichlor puck machine has remained on "3," and I've added five pounds of ChlorBrite since yesterday in a misunderstood attempt to shock the pool.

The appearance is fine, clear and sparkling. It's three years old.

So, can the water be saved, or is this an open and shut "replace 67% of the water," as the Pool Calculator determined? I've armed myself with 12 bottles of Chlorox just in case the other numbers don't support our newbie interpretation of the CYA.

Thanks.
 
I'm usually the first guy to say Drain It! as the first line of offense when I suspect that reducing high CYA and/or Calcium levels would be useful to rectify bad chemistry or algae, but I'm a little troubled by the techniques you use to get to the CYA level you report. (Most especially... testing in poor light, visualizing the dot against the concrete.) I would recommend retreiving a test sample (2 or 3 cups of water) from at least 12" below the surface of your pool and bringing it indoors, during the daytime and with auxliary lights ablaze, test again, with the dot resting on a white/ivory countertop or piece of white paper. If you're still convinced that you have a CYA level above 100, drain away. Read this link and follow instructions carefully.

All this said, if your Calcium and CYA levels are as high as you indicate, you'll save yourself a lot of grief (and time... and money...) by draining and refilling before further treatment. Good luck :cool:
 
Thanks, polyvue, I was hoping for a critique of my testing procedure. I recall reading somewhere on this forum that "waist high" was the appropriate view of the dot chamber, so that's the way we did it. I'd be much happier reading from a white counter top!

As for the determination point, do I need to be able to see the dot edges disappear (a higher CYA number), or is it when I stop seeing the black (a lower number)?

As for the calcium hardness reading, I have no doubt. The water here comes from the Edwards Aquifer, the center of the universe for limestone.

What do you mean about gathering 2 - 3 cups of water? I'm gathering my sample directly in the squeeze bottle, leveling it to 7ml, then topping with R-0013 to 14 ml, shaking for 30 seconds, then introducing it to the turbidity tube. (Taylor/Leslie's kit.)

As for being sure we have in excess of 100, no I'm not. Given the good visible quality of the water, I suspect I've erred somehow. Note that Leslie's rated the CYA at 40, not >100.
 
The CYA test reaction gets sluggish with colder water. You want to make sure the sample has warmed up to room temperature. Also take your sample from elbow deep (~ 18").

To increase the range of the CYA test, dilute the pool water 50/50 with tap water first, then run the CYA test on the diluted sample, and double the reading. You lose some accuracy but it's a pretty subjective test to begin with.

You do want to run the test in good lighting conditions. It's designed for outdoors but not direct sunlight. You need pretty good indoor light to match that. The background shouldn't matter. You might want to check out Taylor's page on the CYA test w/ pics to see just what you should be looking for. (This link has better pics than the one zea3 posted.)

I am struck by the curious behavior of the ChlorBrite. ("But the ChlorBrite did nothing." "That's what is so curious.") 5 lb dichlor in 15000 gallons should add FC 22 as well as CYA 20 and lower pH by .8, according to the Pool Calculator. Yet the next day you see FC 0 TC 3. Because you report it this way, let me guess: You are using the DPD chlorine test (drops that turn the sample pink, and you compare that to colored blocks to get the reading). This test is know for bleaching out at high FC levels, reading 0 or very low when in fact FC is very high.

It seems quite likely you will need to drain a big chunk of water, in which case it is not a good idea to be adding a lot of stuff first. But getting a better handle on your CYA level will give you a better idea how much water to drain. It's easier to do it all at once, if you can.
--paulr
 
Jaywalker said:
As for the determination point, do I need to be able to see the dot edges disappear (a higher CYA number), or is it when I stop seeing the black (a lower number)?

What do you mean about gathering 2 - 3 cups of water? I'm gathering my sample directly in the squeeze bottle, leveling it to 7ml, then topping with R-0013 to 14 ml, shaking for 30 seconds, then introducing it to the turbidity tube. (Taylor/Leslie's kit.)

As for being sure we have in excess of 100, no I'm not. Given the good visible quality of the water, I suspect I've erred somehow. Note that Leslie's rated the CYA at 40, not >100.
Click to expand...
As zea3 pointed out, even the pool stores don't get this right sometimes. And, in my opinion, the test is a bit subjective. Paul gets into more of the detail here, although I think that a white background makes it easier to adjudge the result. I normally fetch 2-3 cups of water and run all of my tests from this sample after bringing it indoors; just taking a 7 mL sample is another alternative. I think the answer to where you take the reading is between when the edges disappear and when the entire dot is obscured. That would seem to be supported by the picture provide by Taylor. In any event, if you're sure about the calcium level, test your fill water. If it's relatively low in calcium (20 ppm or thereabouts and not say, 200 ppm) then you'll do yourself a world of good by draining at least 50%.
 

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Zea3, i don't know how Leslie's ran the test. They poured the sample into a beaker and ran a computer program, but I didn't see any test strips. Thanks for the link - I'll have to run it using the diluted approach for more accuracy - along with the white counter-top, of course.

PaulR, good info. The water was probably under 60°F. I wondered about bleaching from high FC levels, so I put the ChlorBrite in over two separate days, Day One - 2 pounds, Day Two - three pounds. I didn't think that would bleach, but perhaps I was mistaken? I am careful to take the sample from elbow deep, out from the edge, away from the inputs. There was no substantive change after Day One, but Day Two dropped the TC number from >5 to 3.
 
I don't use a white counter but I'll tell you what makes the biggest difference in reading the CYA test to me; Lighting. Reading the test in the sunlight produces the easiest to determine readings. I've had several people at the house read it and we all agree that reading it while standing near a sunny window or outside, is best.

Adding 2 lbs of dichlor to a 15000 gal pool raises the FC ~9 and adding 3 lbs raises it ~ 13. taking a normal FC loss of 2ppm per day that still leaves you with a FC reading of greater than 17 which will bleach out a DPD test. And that's not accounting for any FC that might have already been there.

I think it's time for you to read (or re-read) Pool School and stop using anything but liquid Chlorine. Using Dichlor when you already suspect your CYA is through the roof isn't doing you any good.

  • I think draining is where you're headed but we really need to know a couple of things before proceeding.
  • What your CYA level really is. [/*:m:33e77c5t]
  • What your CH really is. [/*:m:33e77c5t]
  • What the CH of your fill water really is.[/*:m:33e77c5t]
 
Today's numbers:

FC = 0
TC = 1.5 (previously was > 5)
Trichlor puck system set at 1.5 rate (won't easily go past that to "off;" previously was set at "3.")

pH = 7.0
TA = 70

CH pool -> (reduced sample concentration) -> 20 x 25 = 500 to purple, 22 x 25 = 550 to Blue
CH fill water -> (reduced sample concentration) -> 5 x 25 = 125 to purple, 8 x 25 = 200 to Blue

CYA -> (reduced sample concentration) -> 80 x 2 = 160 (reasonably confident of this number)

Water temp = 47°F

Should I assume the FC is actually there at some level and just bleached out, given the drop in CC over the previous few days?

Is there any way to avoid a partial drain at this point?

Thanks
 

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With a CYA level at 160 the question is not if you're going to drain 2/3rd's of it but when. You can do it now or you can wait till next swim season. You can make it easy on yourself there. I won't recommend when you do it, just that you're going to have to sooner or later.

May I ask why you're still using Trichlor and Dichlor to chlorinate your pool after finding this site and knowing what your CYA level is? Not trying to be hard on you just wondering.

A CH of 550 is high but your immediate issue is your CYA. Once you drain enough water to get your CYA down to a normal level your CH will improve.
 
Bama Rambler: May I ask why you're still using Trichlor and Dichlor to chlorinate your pool after finding this site and knowing what your CYA level is?
Click to expand...
Certainly - no offense taken. I haven't used the dichlor (recommended by the guy I paid to teach me about the pool: the pool builder) since I found this site and learned about the CYA issue. I have used the trichlor since I don't know how to turn it off - the regulator only goes down to 1.5, which is where it is now.

I do have a dozen Chlorox jugs, 8 pounds of baking soda, and 4 bounds of Borax, ready to deploy, pending the answer to the "can this pool be saved?" question.

Still, with the CYA level we have, we'll apparently be draining and the trichlor is already paid for, is there a problem with using it to protect the water until I get it changed? That's a real question, by the way...

Another real question is whether I can use the "opening a pool" data for setting up a pool after draining 75% of it and refilling?
 
Are you using the pucks in an inline chlorinator? If so do not put any more in. If you are using a floater take it out. Honestly at this point we aren't sure what the CYA is except that it is high. Paid for or not if you keep using the trichlore the CYA will continue to increase and the available chlorine will continue to decrease. At that point trying to add chlorine via the pucks is like putting Dolly Parton in a training bra, there is just not enough material to get the job done! The pucks are not doing an effective job sanitizing your water and the more you use them the more water you will have to drain to get the CYA at a manageable level. Save the pucks to use after your CYA is under control and you have to go out of town for a vacation or something. As long as they are kept sealed in a dry location they will last for years. If you spent a lot of money on a year's supply of pucks and can't stand the idea of keeping them in storage then sell them on Craigslist. Bottom line, stop using the pucks! (Should we start a chapter of Puck-o-holics anonymous?)

So to answer your question, yes it will cause more trouble to continue using the trichlore until you drain because it is not protecting your water and you will have to increase the % of water to drain since it continues to add CYA.

You will not be able to drain 75% of your pool at one time. Most of the people here will tell you to drain 1/3 of the pool's volume at a time. Draining 75-100% of the water in one shot puts you at risk of doing structural damage to your pool, be it vinyl liner or plaster.

To correct CYA the procedure is #1 test CYA, #2 drain a 1/3, #4 refill, #5 test again, #6 go back to #1 and stop when CYA is at a manageable level. You may not be able to use the start up procedure when you are finished draining and refilling. It will depend on what the test results say at that time.
 
Puck-a-holics anonymous, amen... I have a half bucket out in the shed and I figure it's a lifetime supply, or at least a good many years worth. Judicious occasional use is fine, say when you go on vacation for a week or more. As a regular thing, no, you don't want to do that, even now when you're planning to drain at some point.

Re. draining, I'm not so cautious as zea3, with a vinyl liner the usual advice is to drain down to where you have about 1' of water left in the shallow end; if you go further than that, the liner is too likely to move (and not move back when you refill). With concrete/plaster/etc the structural integrity is not really an issue but groundwater level is. If you try to drain below the groundwater level, either you get your pressure relief valve letting groundwater in (if you're lucky), or you get hydrostatic pressure trying to lift the pool out of the ground (if you're not).
--paulr
 
Sensible advice, politely given - thanks. (Yes, I finally realized that adding pucks to "protect the water" pending draining makes no sense with the CYA as high as it is.)

I'm powerless over the pucks' CYA and I'm swearing them off, except for vacations.

As a suspenders-and-belt person, I expect I will tread the cautious approach and drain/fill 1/3 at a time.

Thanks.
 

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