Time to replace sand?

[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!

[Watermom]

I can just picture those games of Marco Polo now! That is what having a pool is all about! Happy 4th to you, too!

[jonno]

Yay! The FC held overnight at 25 and the CC is between 0.5 and 1.0. Water is crystal clear.

Here's my understanding of the next treatment phase: Let the FC drift down to 15. Once at 15ppm I'll be able to get good test readings for pH and TA. I'll add muriatic acid to keep the pH at 7.0 and continue aerating until my TA settles to 120, then I'll aerate (or add a little borax) until the pH rises to 7.4 - 7.6.


Before I put out an open invitation to swim, I wanted to check with Ben or the other moderators to see if there is anything else I should be doing or watching for.

Also, now that I'm in a new treatment phase, I have several questions:

1. My CYA is well over 100 so my target FC is 8 to 15. Everytime I add liquid chlorine I should bring it to 15ppm?
2. If the morning test is, say 12ppm, should I bring it to 15ppm, or wait until it is lower (but no lower than 8)?
3. When I add liquid chlorine or m. acid, how long before swimmers can enter the the pool?
4. I've ordered polyquat 60 to have on hand. Should I use it only if I see evidence or algae or do you recommend a maintenance dose?

I know that all of this is basic chemistry, but combination of the advice, education, encouragement, and pool owner patience and persistence (POPP) has yielded miraculous results! Thank you thank you.

[Watermom]

I'm doing the happy dance for you!!!

Answers to your questions:
1. Yes
2. You can just test and dose in the evenings.
3. I'd wait about an hour to give it time to mix well. You don't want somebody swimming into a 'hot pocket.'
4. I personally don't use it because I am diligent about my chemistry maintenance. Some people do. It won't hurt but isn't really necessary. If you do decide to use it, know that it will make your FC plummet when you add it. (It is more of a preventative. Once you have algae, it isn't that much of a help. At that point, you just need chlorine and lots of it. You know all about that, don't you!)

You are very welcome. That is why we are here -- to help, educate and encourage. Now, go swim and enjoy that pool!

[jonno]