Dichlor question for newly started pool...

[inferno480]

This weekend I filled a 15' x 48" Intex above ground pool...

It completed filling about 11:30pm Friday night, so I put enough 6% bleach in (55oz) to get my FC to 6ppm per the Beginner's guide @ pool-school/temporary_pool_guide

I ran the filter/pump all night, tested numbers late the following morning and numbers looked good (pH in the middle of ideal range/FC was registering, but not quite 6ppm, closer to 3-4ppm; no CYA yet to test of course), so two people swam in it for about two hours on Saturday afternoon.

Saturday night, I started putting dichlor in (again the recommended amount; 8.8 oz due to it being a 4400 gal pool)... I dissolved the granules into a bucket of pool water first and dumped it into the skimmer.

I tested this morning and the chlorine levels seem pretty high; I am only using test strips, so I can only tell that it's between 5ppm-10ppm. There is also a small amount of CYA registering now, but I would guess less than 10 (seems expected).

We haven't swam in it yet today (Sunday), basically the questions I have are:

1) Is it safe to swim with that much chlorine present? Will it irritate skin/eyes/etc? How does it compare to the amount of chlorine that is present in, say, a public swimming pool?

2) Should I keep adding more dichlor since the chlorine doesn't seme to be getting used-up all that quickly, or should I just add some standalone CYA tonight (and presumably until chlorine levels start to go down some more)?

3) When should I start adding algaecide?

Thanks

 

[Richard320]

1) Is it safe to swim with that much chlorine present? Will it irritate skin/eyes/etc? How does it compare to the amount of chlorine that is present in, say, a public swimming pool?

2) Should I keep adding more dichlor since the chlorine doesn't seme to be getting used-up all that quickly, or should I just add some standalone CYA tonight (and presumably until chlorine levels start to go down some more)?

3) When should I start adding algaecide?

Thanks

1)Shock level for a calculated CYA of 6 ppm is 10. So you should be safe to swim in it. I'm sure the FC is much higher than a public pool, but since you're using test strips, there's absolutely no way to know how much more. You'll just have to find out by trying it if it bothers you. Some people are supersensitive, most aren't. pH is more likely to cause burning eyes.

2) 64 ounces of dichlor will put your 5300 gallon pool to 46 ppm CYA. If you've bought that much already, use it up. Don't use any more than that.

3) I wouldn't bother with algaecide. Keep the chlorine level above minimum for the CYA level, and you'll get no algae. Then again, since you're relying on test strips, you might as well dump it in now.

 

[fast1971chevelle]

i suggest you get a good quality test kit like the tf 100 test kit from tftestkits.net they ship very fast and are the most reasonably priced........Mike

 

[inferno480]

An update... yep, still using test strips but have a TF100 kit on-order. The guy at the pool store claimed test strips were more accurate because in drop-based kits there's no way to ensure the drops were the same size. *shrug* I hate the strips and even if they were less accurate, it seems like the drop kits can test for more and give you more-granular results, so I intend to ditch the strips soon. I am no expert though, you guys are.

I've put the dichlor in for two consecutive nights now; CYA seems a little closer to 30 (probably around 20) but FC seems to be over 5+ but maybe not quite 10. Still a little worried that the chlorine isn't getting "used up" fast enough; Sunday wasn't very sunny and the pool hasn't seen much use. I wonder if by the time I add the 4th night of dichlor what the FC will be? Probably pretty high? 10+? Still safe to swim in then? pH seems stable around 7.2-7.4ish

The pool hasn't gotten a ton of use and it wasn't very sunny on Sunday -- I swam in it for a couple hours Sunday, and the chlorine did not seem excessive (still low compared to a public pool).

I purchased 5lbs of dichlor, definitely not intending on using it all up this season (hopefully it lasts until next?) I'm only putting in 8.9oz each of these "first four nights" based on increasing CYA by 10 for the first four days the pool is up. The guide/pool calculator only indicates to put in 8.88oz for each 10ppm (or did I read something wrong?)

I purchased some Poly-30 algaecide, they didn't have Poly-60 available. Guy at the shop said he's only ever seen Poly-30. Haven't used it yet... still kind of wondering if/when I need to. With the FC kind of high, I get the impression that I don't really need to? Realistically the pool will likely only be up for another month or two at the very most but algae infestation sounds like a nightmare I'd want to avoid.

Thanks for the responses and help! This has been a learning experience for sure...

 

[linen]

An update... yep, still using test strips but have a TF100 kit on-order.

The guy at the pool store claimed test strips were more accurate because in drop-based kits there's no way to ensure the drops were the same size.

The strips are notoriously bad...you can search on here and see example after example of how wrong they are. As for the drop based kit (at least the good one's, i.e. the taylor and the tf-100) Taylor's spec for the dropper tips is 24 drops +/- 1 drop per ml. The other source of error (but not common) can be static build up and can be alleviated by wiping the dropper between each drop (usually not needed by most of us).

Still a little worried that the chlorine isn't getting "used up" fast enough; Sunday wasn't very sunny and the pool hasn't seen much use. I wonder if by the time I add the 4th night of dichlor what the FC will be? Probably pretty high? 10+? Still safe to swim in then?

For a cya of 20 ppm it is safe to swim up to 11 ppm FC. I would probably wait and let your FC drop down to below 5 ppm, before you do your next dose of dichlor, so you can be swimming.

By the way your 15'X48" is probably closer to 4600 gallons, since it is likely only 3.5 feet of water depth (I think it might even be less then that per intex).

I purchased some Poly-30 algaecide, they didn't have Poly-60 available. Guy at the shop said he's only ever seen Poly-30. Haven't used it yet... still kind of wondering if/when I need to. With the FC kind of high, I get the impression that I don't really need to? Realistically the pool will likely only be up for another month or two at the very most but algae infestation sounds like a nightmare I'd want to avoid.

My opinion is to skip the algaecide...you don't need it if you maintain appropriate FC levels.

 

[inferno480]

Thanks for the info, BTW I had been doing all calculations based on 4440 gallons. (41" of water filled to 90%, based on Intex's info)

Still a little worried about skipping the algaecide, is it true that if you start to notice an algae problem that it's too late and you get to look forward to a lot of scrubbing? I'd rather just put some in to be safe... is there a drawback?

And should I really skip/hold-off on more dichlor? Wouldn't I want to get the CYA up higher and within the ideal range to keep the chlorine from dissipating?

Thanks again

edit: I think I see what you mean; don't add more dichlor until or unless more chlorine is needed so I can still swim in it meanwhile

 

[jblizzle]

If you maintain your FC in the recommended range for your CYA level, then the algae can not grow and the algaecide is just a waste of money.

Sounds like you need to start using liquid chlorine if your FC is too low and you do not want to add more CYA from the dichlor.

 

[inferno480]

well, I was actually worried my FC was staying too high/not getting used-up... and would be uncomfortably high by the time the CYA got into the recommended 30-40 range. but it's sounding like the range of the CYA doesn't matter that much as long as my chlorine isn't going away?

I do have some 6% bleach, 12% liquid chlorine, and also some CYA (non-dichlor) I could use. but should I just wait until chlorine goes down a bit then add more dichlor? the start-up guide made it sound important to get CYA to 30-40 ASAP (within four days of filling the pool) or else you lose chlorine rapidly...

 

[linen]

Thanks for the info, BTW I had been doing all calculations based on 4440 gallons. (41" of water filled to 90%, based on Intex's info)

Oops...I think Richard confused me

edit: I think I see what you mean; don't add more dichlor until or unless more chlorine is needed so I can still swim in it meanwhile

Yep, I think you understand. Since you want to swim (and who wouldn't) you just need to be a bit more vigilant during daylight hours so that your FC does not drop below the minimum normal level (2 ppm for 20 ppm cya per poolcalculator.com). As you continue to get more cya in there, adjust your FC levels up appropriately (i.e. at 40 ppm cya, your FC should not drop below 3 ppm, etc.).

 

[jblizzle]

well, I was actually worried my FC was staying too high/not getting used-up... and would be uncomfortably high by the time the CYA got into the recommended 30-40 range. but it's sounding like the range of the CYA doesn't matter that much as long as my chlorine isn't going away?

I do have some 6% bleach, 12% liquid chlorine, and also some CYA (non-dichlor) I could use. but should I just wait until chlorine goes down a bit then add more dichlor? the start-up guide made it sound important to get CYA to 30-40 ASAP (within four days of filling the pool) or else you lose chlorine rapidly...

OK, I misunderstood.

If the FC is staying high, just wait for it to drop before adding more dichlor.

 

[fast1971chevelle]

Correct......as long as you maintain the min fc level per your cya you will not get algae.and after a while you will see a pattern of the fc usage during a typical day of sun and bather load and will be quite easy to maintain, I test every evening at the same time and add as needed.....Mike

 

[inferno480]

Ok, another update. Got the new test kit... numbers are interesting. The stupid strip-based tests basically had the same color for 5ppm-10+ppm of FC.

For one, the FC seems exceedingly high but I haven't had any problems w/irritation or burning since I've swam in it. I hadn't swam in it since my last dichlor application though (it's been cooler and rainy the last two days).

Here are my numbers:

FC = 11 (yep, that's accurate... I first used the larger sample size then gave up after 50 drops)
CC = 0 (or very close to it)
pH = between 7.3-7.4
TA = 70
CH = 70
CYA = 40

I don't see a mention of "combined chlorine" in the Pool Calculator, is that anything to worry about with it being 0?

Overall things look to be pretty stable when I look it up using these numbers and the paper wheel that came with my test kit.

pH seems a tad bit low (presumably from the dichlor applications), should I look toward increasing it or leave it be?

What should I do about the high FC? Just let it dissipate over time or look toward changing out some water? I'm assuming 11 is still safe to swim in since it doesn't seem to bother the skin/eyes/etc. Doesn't have that "chlorine smell" like I'm used to w/public pools either.

One last side question... we received a significant volume of rain in the past two days; if there's a significant amount of rain water mixed in with the pool water, should I do do anything about that (drain some water and/or replace w/tap water?) What is the typical impact on pool chemistry when you introduce a lot of rain water?

 

[UnderWaterVanya]

For one, the FC seems exceedingly high but I haven't had any problems w/irritation or burning since I've swam in it. I hadn't swam in it since my last dichlor application though (it's been cooler and rainy the last two days).

It's higher than you have to have - but not too high. With your CYA level you would need to keep the minimum FC at or above 3 and stay below 16 under most circumstances. The target for most people would be around 5-7ppm so that at the end of the day it is at or above 3.

Take a look at this chart to understand how as CYA goes up the amount of FC you need also goes up. The truth is the "free" chlorine isn't all that free - it's bound up to the CYA.

Here are my numbers:

FC = 11 (yep, that's accurate... I first used the larger sample size then gave up after 50 drops)
CC = 0 (or very close to it)
pH = between 7.3-7.4
TA = 70
CH = 70
CYA = 40

Those look great! CC's are bad - so not having any is great. The only time they are of any real concern is if you get an algae outbreak - they help you determine when you can stop shocking the pool.

pH seems a tad bit low (presumably from the dichlor applications), should I look toward increasing it or leave it be?

Since you will be using liquid chlorine the pH will likely drift up on its own.

What should I do about the high FC? Just let it dissipate over time or look toward changing out some water? I'm assuming 11 is still safe to swim in since it doesn't seem to bother the skin/eyes/etc. Doesn't have that "chlorine smell" like I'm used to w/public pools either.

Relax and swim as is. The higher FC is actually not very high - there is a deep end post on this that delves into the chemistry but the reality is that most of it is held in reserve in the CYA. The smell you get at public sites is from CC's - they stink and burn and make your skin feel itchy etc.

One last side question... we received a significant volume of rain in the past two days; if there's a significant amount of rain water mixed in with the pool water, should I do do anything about that (drain some water and/or replace w/tap water?) What is the typical impact on pool chemistry when you introduce a lot of rain water?

Just check for FC and CC's. Assuming FC is over min and under shock and the CC's are no more than 0.5ppm you're fine. Essentially there is limited impact from rain, in theory sometimes pH is affected but usually not enough to matter. Watch your CYA over time - if you get too much added water your level will slowly drop - keep it optimized at 40 as you have it if you can but don't overshoot it.

 

[jblizzle]

Send like you could use reviewing some of the Pool School articles about chemistry.

CC are bad, so good to be zero. They also cause the smell and irritation.

Your pH is fine.

Safe to swim if the FC is less than the shock level for your CYA ... see the CYA/FC chart in Pool School. You are under that level so you are fine.

Also the water should be clear, the FC should be greater than the minimum in the chart, pH should be in range, and the CC should not be more than 0.5ppm to be safe to swim.

Enjoy.

Posted from my Droid with Tapatalk ... sorry if my response is short

 

[inferno480]

Thanks again, you guys are great... yeah, I still have some reading-up to do, I've really only looked at the temporary/ABG pool start-up guide, and the pool calculator itself... good to know CCs are bad!

BTW, the water is still crystal-clear... I do have some very small leaf particles and things floating but I blame that on my gimpy Intex pump & filter. Next season I'll get something better, but this really only needs to get me through another month or so.