I would have to raise the FC to about 30

[chem geek]

My other concern is I have a 3 year old daughter that swims daily, when I have shocked before to about 12FC following the companies guidelines it takes about 3 days for the FC to drop back to about 5. I could never let our Daughter swim in 30FC and I fear the pool would be closed for weeks while i wait for it to drop back down.
:
My other concern is bleaching my lovely deep blue liner.
:
My pool is clear but get a lot of dead algea dust on the bottom it has also been super hot here recently

30 ppm FC with 80 ppm CYA has the same active chlorine level as 0.4 ppm FC with no CYA so less than found in indoor commercial/public pools. So while about 8 times higher than the normal non-shock target level for your SWG, it's not extraordinarily high and it won't be for months at a time. We've had hundreds if not thousands of people shock their pools when they have algae or similar problems (usually when first joining this forum) and none of them with vinyl pools has ever reported any fading from the shock process.

Now, that said, you should add the chlorine slowly over a return flow in the deep end with the pump running and then lightly brush the wall and floor where you add it to ensure thorough mixing. Though this procedure is critically important when adding acid, it's also a good idea when adding chlorine as well.

If the dead algae is a yellow/mustard dust-like substance (that might look green on a blue vinyl background) and if it is mostly in the shady area of the pool, then you may have yellow/mustard algae which is harder to get rid of and has more extensive procedures. Are you able to scoop up any of the algae carefully with a net? If so and it looks green out of the water or if it is growing in sunny areas of the pool, then it's most likely green algae (I'm hoping that's all it is).

 

[Michaelandliz]

Hi,

Thanks for the thorugh input.

I actually did a lot of reading on mustard algea on this forum and even did the cup test, I put some in pool water in a cup for 2 days to see what grew and nothing did. I then vac'd the pool twice with my Haywood robot where as before i was brushing, and since doing that I have had little repeat, I also raised my FC from 3-5.

The jury is still out in regards to Mustard, its a tough call, the pool is in direct sun nearly all day, the dust was not more in one area than another although it was a bit patchy.

I cant scoop any up as it is way too fine and in no way thickly coating, I notice it only as darker patches on the liner or rather I did before the vacuming.

In regards to readings, tonight i re-did the CYA test and it came out at somewhere between 60-70 which is not a bad thing as it means less chlorine needs adding, and I cna keep my FC at 3 instead of 5

My Fc this evening was at 5, just before sundown, I will get up early tomorrow and test again but the sun is on the pool from 5.30am so I expect some drop before the pool comes on at 7am?

Again thanks for all your help. I will report back.

 

[frogabog]

Assuming your pool will lose ~50% of it's chlorine tomorrow, if you start the day with 5ppm and lose half you'll end the day under the minimum of 3ppm for your CYA level by sundown.

If your SWG will start in the morning and produce at least enough to keep you above 3ppm always, and end the day with enough reserve to do all over you should be ok. The point is to never fall below 3ppm. It might be a good idea to test throughout the day tomorrow while the SWG is running to see how it's keeping up.

Additionally, if the sun is on the pool, I'm afraid you'll have to test before this occurs to be able to tell if you're holding chlorine overnight. An hour and a half of sun is plenty enough to skew an OCLT.

 

[Michaelandliz]

Up at 5.50am sun already up!

Just tested the pool and the FC was at 4.5 so a loss of .5 overnight

there was still about 30 minutes of daylight left when i testd the pool last night and a good hour this morning, so I am assuming this loss is acceptable. My CC was around .2

No sign of any dark patches on the pool floor and no dust on the steps.

Maybe a newbie panicking over some dust when the pool just needed vacuming, the only thing I will add however is up until 2 days ago it was in the high 80's to 90's here every day and now a bit more seasonal. I am thinking with the very high heat and sun the pool was strugling and once i raised the FC to 5 it was able to keep up, and the dust was alagal die off?

 

[supertune]

Hi Michaelandliz,
I did the same thing last year with my Intex pool.
Now with the new pool this year... I keep my chlorine up 1 ppm higher than the Chlorine/CYA chart and that has made the pool never need anything except some vacuuming, after I got the TA right for my pool (100) to keep the pH stable at 7.5-7.6 all the time.
55 CYA and between 6-8ppm FC chlorine.

Chuck

 

[Michaelandliz]

Yep things are looking good, no more brown dust. I guess my FC was too low allowing the algae to get a hold. Pool is crystal clear.

 

[duraleigh]

Pool is crystal clear.

Nice work, M&L

 

[techguy]

 

[Michaelandliz]

cloudy after shocking

Hi
Just a quick question - I followed the previous advise on here about shocking my pool, I added 10L of sodium Hypo liquid but on adding it the pool has gone a bit hazy/milky. I have never used sodium hypo before only calcium and used to cloudy water with that and why the switch.

Is this normal?

Only just added it by the way

 

[jblizzle]

Re: cloudy after shocking

What did the water look like before you added the liquid chlorine?
What strength?
How big is the pool? {Helps to add your pool details in your signature}

 

[linen]

Michaelandliz, I moved you post to your original thread, since very little time has gone by since your last thread on your water (4 days). It will help us be more efficient.

What was the reason to start the shocking process?

 

[Michaelandliz]

Hiya

I shocked for two reasons

1. we had a massive storm yesterday
2. I noticed small patches of what looks like Algae in the corners or on the return jet.

better to be safe I thought.

pool params prior to shocking

FC - 5.0
CC - 0.2
alk - 100
Ca - 250
pH - 7.2
NACL - 3000
pool size - 17,000gal
CYA - 60-70

 

[linen]

As jbliz requested, could you put your pool and equipment details in your signature?

If it isn't there already, I would bring you pool up to shock level (20 ppm FC for 70 ppm cya from poolcalculator.com) and do the overnight chlorine loss test (OCLT): http://www.troublefreepool.com/pool-school/overnight_fc_test

 

[Michaelandliz]

seems better now, guess newbie panic. I have an adverse reaction to adding chemicals to the pool, always concerned of creating more problems than I had before ;(

 

[Michaelandliz]

Ok so next question would be - how long before my pool is back to FC of 5 now its at 22FC? I have turned the SWG off for now.

 

[linen]

I have an adverse reaction to adding chemicals to the pool, always concerned of creating more problems than I had before

Not a bad concern to have, but if you follow the methods taught on here, you will know what your pool needs and how much to use...and use no more than you need, or things you don't need.

Do the OCLT tonight, read the process carefully, there are a few pitfalls. Ask, if any questions come up.

 

[linen]

Ok so next question would be - how long before my pool is back to FC of 5 now its at 22FC? I have turned the SWG off for now.

Yes leave the swg off. Was it on the last time you did the OCLT? It should be off when doing the OCLT, and in general we recommend leaving it off during the shocking process. As for how fast you will be back down to 5 ppm, don't worry about that now until you pass the three criteria in the shocking process (also at the bottom of my signature).

Speaking of signatures, thanks for updating yours! Could you put in what type of swg, filter and pump...including sizes?

 

[frogabog]

Cloudiness while shocking could be a couple of things, but mostly cloudiness is actually dead algae (green algae is alive, dead algae is white/grey). Cal-hypo can cloud up the water after adding it due to the calcium but it'll also kill algae and turn it white/grey. Bear in mind that this is a normal reaction, and the solution is to filter the dead algae out.

I also noticed that it looks like you're using the 25ml sample to test for chlorine (FAS-DPD). Go ahead and use the 10ml sample, and count each drop as .5ppm. That will save your reagent by half this season, and .5ppm is good enough for these purposes.

Your adverse reaction and anxiety about adding chemicals to the pool likely comes from past pool store advice to "dump pounds of such and such in", perhaps? Now that you've got the pool calculator, a proper test kit, and some knowledge I hope you will be able to relax a bit because you know exactly what you're putting in the pool, what it should result in values by testing, and can confirm these values through testing. It's way better than anti-anxiety meds... this pool calculator :~}

 

[Michaelandliz]

Thanks for the advise, I have updated my signature, please let me know if you need more details.

I used to use Cal Hypo but I hated the cloudyness and also the fact it raiased my calcium, which already is at 270. This is the first time I have used sodium hypo.

Pool is now looking quite clear I guess dumping 2 gallons of anything in the pool will have some effect on the water clarity.

The FC is currently at 25.5 on a 10ml test. I always have turned off the SWG before shocking the pool.

My concern of the level staying high for too long is bleaching the nice dark blue liner

 

[linen]

Thanks for the advise, I have updated my signature, please let me know if you need more details.

Your going to hate me...could you put the sizes of your equipment in also...and, could you reduce your sig to five lines...it takes up less space in the thread

My concern of the level staying high for too long is bleaching the nice dark blue liner

25 ppm is not a problem at your 60-70 ppm cya level since you "active" chlorine is much lower than that. Put it this way 25 ppm at 60 cya is less active chlorine than 1 ppm FC at 0 cya (what you might find at a public pool)...so no worries about the liner, and you wont be at this level for very long.