Draining pool and starting fresh, help with fresh water chemistry

[mknauss]

The only issue of putting granular CYA in the skimmer is it can take upto a week to completely dissolve and be in the water there for at least a week you can't backwash or clean the filter.

The CYA in a sock, and that in the skimmer. I do the same.

 

[Dirk]

The only issue of putting granular CYA in the skimmer is it can take upto a week to completely dissolve and be in the water there for at least a week you can't backwash or clean the filter.

Agree, but to clarify: the granules can dissolve from the sock in just a half hour or less (especially if you work the sock periodically by squeezing it with your hands), so the sock doesn't need to stay in the skimmer for very long. The CYA particles then get sucked into your filter, where it can take a week, or even longer, for them to dissolve fully and start working with your chlorine out in the pool.

This is especially inconvenient for a sand filter, because while you're waiting for all the CYA to make it to the pool, you can't backwash the filter or else you'll be flushing out the undissolved CYA along with the crud.

For me, I'm never in such a hurry to add CYA that a week is an issue, plus, I have a cartridge filter, so I don't backwash. The wait doesn't outweigh the risk to my plaster.

You also have to make sure you position the sock such that it can't block the flow through the skimmer's basket, or get loose and float out into the pool. I don't actually use a sock, I use a laundry "fine delicates" mesh bag with a very fine mesh, and hang that from my skimmer's access hole, by trapping one end of the mesh bag between the hole's lid and hole's edge. The bag is large, semi-transparent, and has a zipper, which all help the process go smoothly.

 

[Dirk]

My "CYA sock" is similar to this one.

 

[wireform]

My "CYA sock" is similar to this one.

I have something much better then that. When I get a chance....

 

[Dirk]

I have something much better then that. When I get a chance....

Yes, but can I wash my unmentionables in it too?

 

[proavia]

Yes, but can I wash my unmentionables in it

TMI Dirk, TMI

 

[Chefwitchyherb]

Yah, sorry, I was a bit late to your thread. I was hoping I was in time but figured you might have already begun/finished your fill. Knowing the water volume is important for testing and dosing, obviously, but there are work-arounds. As you mentioned, measuring is one. But there's another.

If the calculations you make from testing and your "best guess" water volume result in accurate dosing, that's all that matters, not the numbers themselves. For example, if you test and Poolmath tells you to add 30oz of chlorine to get your FC to 5ppm, and you then add 30oz and a half hour later test again, and get FC5, then your water volume "guesstimate" is fine! Conversely, if you consistently perform that check and are alway off (like, say, you always end up with too much FC), then your water volume number is likely the culprit. So you adjust that volume number until testing confirms that the amount of chlorine you dose always gets you to the expected FC. The point is to get the correct FC, not fret over the actual amount of water in your pool.

Same goes for other chemicals, of course, but chlorine, or acid for pH, are the easiest testing/dosing processes to use to confirm your water volume number. If you're interested in trying this out with chlorine, do both tests (before and after dosing) after the sun goes down. This eliminates the sun from the equation, which can affect the test results.

That's an excellent idea. My numbers do seem wrong. Pool calculator said to add 73 oz liquid 10% chlorine to raise the ppm of FC up to 4ppm. I did and it raised it to 2.6....although my CYA IS 0. I added an additional 28 oz chlorine per pool calculator. I just tested and FC is 2.6......
I need to go get granular CYA....this liquid stuff my husband claimed was cheaper, is garbage.

 

[Chefwitchyherb]

I burned CYA acid stains into the bottom of my BRAND NEW plaster by using liquid CYA. That "settles in the bottle" problem @mknauss described to you was the culprit. I was dispensing the liquid directly into the water, and the last clump, which had settled in spite of my vigorous shaking, dumped out and sunk directly to the bottom. In the time it took me to run and get the pool brush, it was too late. Five years later and the stain is still there.

Liquid CYA is the devil! Always use the granules. If you're determined to use up the liquid, then pour it into a large bucket first and mix it up well. Dispense is slowly, constantly stirring, and beware of that "last clump." Keep adding water to the bucket while dispensing, too, so that even the clumpy stuff gets well diluted before entering your pool. Don't get any on your deck. Have a running hose by your side to rinse the deck just in case.

Personally, I now never introduce any type of CYA into my pool. I put granules in a sock and the sock in the skimmer. There are some issues with doing it that way, but staining your pool surface is not one of them... Never again.

I didn't realize it was the consistency of a thick slurry (cornstarch and water used to thicken Asian sauces). As for staining, we moved from one city to another. We had our old pool resurfaced with pebble-sheen. This one is plaster, built in 1996. I'm certain it's the original surface. It's stained, it's chipping, cracking, chunks are missing. When we drained it I got some of the stains out but not all of them.

 

[Chefwitchyherb]

You will need more CYA. Get granular. To get to 50 ppm CYA you will need to add 3 more pounds via the sock method,.

Thank you, sir. The morning test says my FC is at 2.4ppm, after adding 101 oz liquid chlorine 10%. In addition to a floater with trichlor, which I'd like to use up because it's a full bucket.
At 4pm yesterday test results stated chlorine was at 2.6ppm. My water has debris, I don't understand this filter/pump/pop-up blower things (useless!). Water is cloudy.

With all the above being said, I plan on adding the rest of the liquid CYA and getting granules. Knowing I have a floater with trichlor, do you still recommend I add 50%-75% of CYA according to what the TFP calculator calculates?

 

[mknauss]

If you are going to use the trichlor now, do not add anymore CYA. Test it weekly. When it gets to above 40 ppm, discontinue using the trichlor.

 

[Mdragger88]

If u are using trichlor pucks - they are acidic so watch your ph & ta & take their effects into consideration before adding acid. PoolMath effects of adding can help u see the effects of each puck once dissolved (regular pucks are 8oz & jumbos are 10oz)

 

[Dirk]

I'll leave the chemistry to Marty (@mknauss), he knows his stuff. He was my mentor/savior when I first joined TFP. I'll just add this: if you're not getting the expected FC after adding chlorine, there may be other factors in play. I described how an inaccurate water volume number might be the culprit, but there could be at least two others.

If your pool has algae, that could be affecting your FC. Not likely with a brand new fill and CC of zero, but if the pool was badly infected prior to new water, the algae could have survived in hidden spaces: like inside a ladder, or a light niche, or in the skimmer, etc., and then reinfected your pool. Cloudy water is a symptom of a few things, algae is one. If your CC is still at zero, that's good, and would indicate little or no algae, so stay on top of that test. Check hidden areas if CC rises and the water stays cloudy.

You also have to be sure your chlorine is fresh. Chlorine degrades over time. If you're storing it in a hot place, that could weaken the chlorine. How it's handled where you buy it could be an issue, or how long it's been on the shelf. If they aren't selling a lot of chlorine right now, who knows how old it might be. Some chlorine products have date codes (though they are hard to read), so that is one check to see how old the chlorine is. If your chlorine is not full strength, then all your dosing math will be off.

Here is some info about chlorine dates and freshness:

Chlorine Date Code Decoder/Easy Way to Measure Strength.

Hi, I just joined TFP this season and pool is looking great. TFP is an awesome resource. Thanks I thought the information below might be helpful for some of the forum participants. I recently bought 1 jug of 10% Liquid Chlorine that was actually 4.5%. It had a 2013 date code. I now am very...

www.troublefreepool.com

 

[Chefwitchyherb]

I'll leave the chemistry to Marty (@mknauss), he knows his stuff. He was my mentor/savior when I first joined TFP. I'll just add this: if you're not getting the expected FC after adding chlorine, there may be other factors in play. I described how an inaccurate water volume number might be the culprit, but there could be at least two others.

If your pool has algae, that could be affecting your FC. Not likely with a brand new fill and CC of zero, but if the pool was badly infected prior to new water, the algae could have survived in hidden spaces: like inside a ladder, or a light niche, or in the skimmer, etc., and then reinfected your pool. Cloudy water is a symptom of a few things, algae is one. If your CC is still at zero, that's good, and would indicate little or no algae, so stay on top of that test. Check hidden areas if CC rises and the water stays cloudy.

You also have to be sure your chlorine is fresh. Chlorine degrades over time. If you're storing it in a hot place, that could weaken the chlorine. How it's handled where you buy it could be an issue, or how long it's been on the shelf. If they aren't selling a lot of chlorine right now, who knows how old it might be. Some chlorine products have date codes (though they are hard to read), so that is one check to see how old the chlorine is. If your chlorine is not full strength, then all your dosing math will be off.

Here is some info about chlorine dates and freshness:

Chlorine Date Code Decoder/Easy Way to Measure Strength.

Hi, I just joined TFP this season and pool is looking great. TFP is an awesome resource. Thanks I thought the information below might be helpful for some of the forum participants. I recently bought 1 jug of 10% Liquid Chlorine that was actually 4.5%. It had a 2013 date code. I now am very...

www.troublefreepool.com

I know chlorine degrades over time and heat speeds the process up. The chlorine I used was sitting in the garage since October....so 100°-ish for a couple months. I just got 5cs from HD for $9.88. Lowe's wanted $12.89! They're out of their mind!
Now we when drained, it was a SWAMP. I did raise the chlorine level when it got low enough. But I didn't SLAM. The water was so full of CYA from previous owners, I had to wait until it was almost empty for even a half gallon of chlorine to work. So I bet there's still algae in there....
I'm going to SLAM and see if it clears.

 

[Dirk]

Great, sounds like you have multiple issues that you're working on, but that you're working through them all. Chin up, you'll get there.

If you're going to SLAM, @mknauss or others can help you coordinate that, along with a strategy about SLAMing and CYA levels (they go hand-in-hand).

 

[Dirk]

I know chlorine degrades over time and heat speeds the process up. The chlorine I used was sitting in the garage since October....so 100°-ish for a couple months. I just got 5cs from HD for $9.88. Lowe's wanted $12.89! They're out of their mind!
Now we when drained, it was a SWAMP. I did raise the chlorine level when it got low enough. But I didn't SLAM. The water was so full of CYA from previous owners, I had to wait until it was almost empty for even a half gallon of chlorine to work. So I bet there's still algae in there....
I'm going to SLAM and see if it clears.

There was a time when the long term costs of sanitizing with chlorine were about equal to the long term costs of running a SWG. Then precious metals costs drove the cost of SWGs up, and the math wasn't as good. But now with crazy chlorine costs, maybe the "new math" is looking better. An SWG means no more lugging chlorine boxes, or looking for best deals, or stale chlorine. SWGs make your chlorine, on site, fresh every day! Something to think about after you get your chemistry figured out...

 

[Chefwitchyherb]

Great, sounds like you have multiple issues that you're working on, but that you're working through them all. Chin up, you'll get there.

If you're going to SLAM, @mknauss or others can help you coordinate that, along with a strategy about SLAMing and CYA levels (they go hand-in-hand).

Ok. So what you said earlier about estimating my pool volume? It's got to be wrong.... At 1:30 or so I added 1 gallon and 2 cups chlorine to the pool, which should've raised a 15k gallon pool with 0 CYA up to 10ppm FC. I just tested it and it's 4.6!!!!!!! So my volume is more than I measured. I don't math well.....

 

[mknauss]

With 0 CYA, the half life of FC in a pool with the sun shining on it is 50 minutes.

or you have algae in your pool.

 

[Chefwitchyherb]

With 0 CYA, the half life of FC in a pool with the sun shining on it is 50 minutes.

or you have algae in your pool.

I'm thinking both. I really regret not measuring with the water meter...

 

[Dirk]

Remember, I mentioned you should do both FC tests (before and after dosing) after the sun goes down. Marty's explanation is why. You might try an OCLT (Overnight Chlorine Loss Test). That would confirm the presence of algae. So: pump running, sunset, test, dose, 30 minutes, test again, overnight, test again. You'd ignore the first test result (that's only needed to determine how much chlorine to add), and compare the second and third. If there is significant FC loss between the second FC test and the third one (the next morning) that would suggest an algae problem. Be sure to test CC each time you do an FC test, as CC is a secondary indicator for algae.

Perform the Overnight FC Loss Test (OCLT)

The Overnight Chlorine Loss Test tells if the SLAM is finished or if you need to start a SLAM. This article says how to do the OCLT.

www.troublefreepool.com

If you have cloudy water OR overnight FC loss OR elevated CC, you might have algae. If you have two of those, or all three, you very likely have algae and need to SLAM.

 

[Chefwitchyherb]

Remember, I mentioned you should do both FC tests (before and after dosing) after the sun goes down. Marty's explanation is why. You might try an OCLT (Overnight Chlorine Loss Test). That would confirm the presence of algae. So: pump running, sunset, test, dose, 30 minutes, test again, overnight, test again. You'd ignore the first test result (that's only needed to determine how much chlorine to add), and compare the second and third. If there is significant FC loss between the second FC test and the third one (the next morning) that would suggest an algae problem. Be sure to test CC each time you do an FC test, as CC is a secondary indicator for algae.

Perform the Overnight FC Loss Test (OCLT)

The Overnight Chlorine Loss Test tells if the SLAM is finished or if you need to start a SLAM. This article says how to do the OCLT.

www.troublefreepool.com

If you have cloudy water OR overnight FC loss OR elevated CC, you might have algae. If you have two of those, or all three, you very likely have algae and need to SLAM.

Ok. Got it! I will do this tonight and see what the results are. I hope it's just algae and not the pump...