Time to replace sand?

[jonno]

6:40a FC 23.0 and CC 1.0 - will continue testing and topping to 25ppm today.

[Watermom]

Carl, Watermom, Janet, or Ben -
I have a question about the timing of taking an end-of-day FC test and when to take it the next morning. To end the shock phase, I know I want a FC that loses no more than 1ppm overnight, but when does "overnight" start and end? From reading other posts, I thought the last test of the day can be taken whenever the sun is off the pool and the first test the next morning is to be within two hours of sunrise.

This is correct.

This evening, I did a test at 7pm and the FC was 25.5. I thought that was late enough to be my final test. Out of curiousity, I tested again 3 hours later at 10pm and was surprised that the FC dropped 4ppm (from 25.5 to 21.5). I added almost a gallon of bleach to bring it back to 25ppm, but this got me wondering.

Here're my questions:

• [1]Why did the FC drop so much between 7p and 10p?
  [2]Is it because the FC is still fighting nasties in the water? The CC at 10p was 1.5, so I think this also is a clue that the shock level of bleach is still needed.
  [3]The sun didn't actually set until 8:38p tonight - could the UV rays hitting the pool indirectly between 7p and 8:38p also have contributed to the drop in FC?
  [4]The water is so invitingly clear, how many more days should I be prepared to continue frequent testing and keeping the FC at shock level (i.e., 25ppm)?

Sorry to be hounding you with so many questions - I'm curious about the chemistry and I've also got several eager swimmers attracted to the sparkling water.

1. Your statement in #2 answers it.
2. Yes.
3. I don't know. I wouldn't think the sun at that late hour would be strong enough to cause much chlorine loss, but why don't you wait a little later tomorrow evening before testing.
4. Hopefully not too much longer. Keep your fingers crossed for sometime this weekend.

Don't worry about all the questions. That is why we are here. Sorry none of us replied to this yesterday. It has been pretty busy around here lately and believe it or not, we all have lives outside this forum!

[jonno]

Thanks Watermom. I'll try to test around 8. Last night I had to test at 6:30p and this morning at 7a the FC was 23.5ppm (CC barely 1.0) - that's the smallest overnight drop so far. I'll keep testing during the day. I'm almost out of the R-0871 titrating reagent - a 2oz bottle used up in less than a week. But testing 5 or 6 times a day and using 50+ drops every test consumes a lot. I had already ordered more, but then I found that Amato industries is closer to my house than the pool store (they have two locations, here in MD and in northern VA - how lucky is that! The woman there is very nice and I can pick some more up today. I'll keep my fingers crossed that the FC will start to hold steady.

By the way, the skimmer sock really makes a difference! Every morning and evening for the past days, I've taken it off and swished it around in a bucket of water to clean it off - not only does it leave the bucket water full of tiny insects and bits, but it turns the water very cloudy - so the sock is trapping tiny stuff too. I don't ever remember the water looking this clear!

I am a happy convert to BBB!

[TheGoose]

Maybe I missed it, but what exactly is a skimmer sock? Thanks in advance.

[PoolDoc]

@ Goose
Skimmer Socks at Amazon

@ Jonno, others
Coral Chemical's Green to Clean is just ammonia!

Instead of ""Disodiumsalt of ethylenediaminetetraaceticaciddihydratediammoniums ulfate", which is Fred Luth's attempt to obfuscate what he's selling, the chemicals should be listed as

Ethylenediaminetetraacetic acid (EDTA) ?%
Ammonium sulfate ?%

OR

Ammonium sulfate EDTA 100%

Regardliess, it's mostly ammonium sulfate, which is an industrial waste product that I have bought in 100# bags for about $10 a bag! (I do think they are using a somewhat purified version, that may cost more than $10 cwt.)

Coral Chemials -- used to be Coral Seas -- is a one product company, like United Chemical. But where United Chemical sells sodium bromide, mixed a bunch of different ways, Coral sells ammonia, blended 2 ways: "Green to Clean" and "Yellow Out". I encountered Fred Luth at an NSPI trade show years ago, and thought he was going to jump down my throat when I asked him if "Yellow OUT" was just ammonia.

[jonno]

The pool looks great! But I'm still in a shock cycle. Went swimming today for the first time this season - it made me remember that the pool is not just a big science project. It. was. wonderful!
As of 8pm:
FC 25.5
CC 1.0
pH 7.4 (added 1 qt m. acid)
TA 180
I'm hoping that one of these nights the FC will hold. POPP.

[jonno]

I couldn't test within 2 hours of sunrise because we had a major storm - almost an inch of rain (desparately needed).
9am numbers:
FC 21 (-4.5 drop over 13 overnight hours - could some of this be dilution from the rain water?)
CC 0.5 (yay!)
pH 7.2 - Since the FC is higher than 15, this is falsely high, so I'm hesitant to add any more m. acid until I can lower the FC below 15.
TA 170 - Probably not a good reading due to high FC - it turned from green to blue at 140, light orange at 160, orangey-reddish at 170
More storms and rain today, but I'll keep topping off the chlorine level to 25 throughout and see how the FC holds tonight.

My pool is an unbelievable transformation - thanks to Ben, forum moderators, and the community. Ben - Have you considered starting an area for posts of appreciation and success stories? Perhaps under the group Ben's Corner, Water Treatment Testing and Problems, or even Odds and Ends. Such an area would be encouragement for people with big problems to know that the POPP is worth it. My path from swamp to crystal clear water covers eight pages of posts - but if there were a Success StoryArea, I would condense it to a single post with a few before and after photos and put in a link to this thread for anyone who wants details.

[Watermom]

My pool is an unbelievable transformation - thanks to Ben, forum moderators, and the community. Ben - Have you considered starting an area for posts of appreciation and success stories? Perhaps under the group Ben's Corner, Water Treatment Testing and Problems, or even Odds and Ends. Such an area would be encouragement for people with big problems to know that the POPP is worth it. My path from swamp to crystal clear water covers eight pages of posts - but if there were a Success StoryArea, I would condense it to a single post with a few before and after photos and put in a link to this thread for anyone who wants details.

Jonno,
I have been talking to Ben lately about this very thing. Really glad your pool is doing so well. Hopefully you are just almost there. Glad you swam!

[CarlD]

"Glad you swam!"

That's what it's all about, isn't it? Swimming and playing and having fun! I was in with the boys at 8pm last night and we had a blast, there till the sun went down and the lights started doing their job!

The BEST thing about this experience is you will almost certainly NEVER go through it again!

Carl

[jonno]

Lost 3.5ppm of FC last night - this was over the course of 11 hours (from 8pm to 7am). Still waiting for the loss to be no more than 1ppm overnight, but the CC was only 0.5 and that's encouraging!

After adding bleach to bring it up to 25 ppm, I spot-vacummed up the visible dirt in the areas where it tends to gather - in deep end valleys, scattered over the shallow end, and in indents that pock the slopes. Then I brushed the bottom and walls to suspend the finer sediments.

Even with the brushing action stirring up plumes, the visibility is so clear I can count the bristles on the brush even while it is on the very bottom - 8 feet down. Just a week ago, I was excited because I could just make out a faint dark blob that was my pool brush head on the bottom. A week or so before that, the brush head would disappear completely within 10 inches of the surface!

The shape of the pool is an extended hopper design by Spartan. It has steel walls with a sand bottom - we built it in 1968. After 13 years, the current liner has a number of smooth craters from swimmers heels and toes hitting hard from jumping in, or pushing off in a frantic escape from marco polo. These craters cause mini-eddies in the circulation and the tiny specks accumulate - like debris colonies. For a quick vacuum like today, I use a vacuum head that has no brushes - it is made to be used on concrete pools, but it works well for a quick cleaning.

This is my third liner - the first lasted 17 years, the 2nd 13 years, and this one is in its 14th season so I'm resigned to its scalloped subterrainian landscape. Hope I can stretch a few more years out of it.

I'll post again tomorrow morning with the new numbers. Happy fourth of July everyone!