New pool owner, trying to get my chemicals balanced

[PoolDoc]

Your TA is not an issue with a vinyl pool. The only reason to add more -- in your case -- is if you find the pH becoming unstable and fluctuating quite a bit.

[Watermom]

+/- 5 degrees isn't really gonna matter as far as your pool goes.

[mitchryan912]

So I'm pretty much OK, especially considering the water looks fantastic?

[Watermom]

Your chlorine has dipped a little low a few times. Keep it within the minimum/maximum range based on your CYA and you'll be fine. Otherwise, everything looks fine.

http://pool9.net/cl-cya/

[mitchryan912]

Your chlorine has dipped a little low a few times. Keep it within the minimum/maximum range based on your CYA and you'll be fine. Otherwise, everything looks fine.

Yes, I've been trying to do that, but suddenly the ability to retain a good level of chlorine stopped, and chlorine has been disappearing a lot faster than before. I added a bit of info from before the 8th of July, when I got my K-2006 kit:

Screen Shot 2014-07-20 at 1.01.57 PM.png

We had a good bit of daily rain from the 9th to the 15th, and somewhere in there I had a filter valve leak where I slowly lost about 1000 gallons. Diluting the pool with fresh water probably had something to do with the change in stability, but I'm not sure what else could have caused it, other than not putting as much chlorine in daily or every other day in that rainy period?

I was using an OTO kit between July 2nd and 8th, and it was VERY dark yellowish every day in that time frame, so the chlorine was holding up well, though I admittedly don't have an very good idea of exactly how much chlorine there was.

[Watermom]

but I'm not sure what else could have caused it, other than not putting as much chlorine in daily or every other day in that rainy period?

Yep. That'll do it. We see it all the time. Usually it is people who come onto the forum and tell us that the rain caused their algae which isn't the case. Usually it is because people aren't as diligent about keeping tabs on their pool when it rains.

As long as you are aware and watching to keep your chlorine levels in the proper range, you'll be fine.

Hope this helps!

[mitchryan912]

Yep. That'll do it. We see it all the time. Usually it is people who come onto the forum and tell us that the rain caused their algae which isn't the case. Usually it is because people aren't as diligent about keeping tabs on their pool when it rains.

As long as you are aware and watching to keep your chlorine levels in the proper range, you'll be fine.

Hope this helps!

I guess I got complacent over the course of the first 2 weeks of July where it stayed above 3.0 ppm, where I didn't really add too much chlorine except for a 2.5 gallon shock on the 1st, some amount on the 9th (probably a quart or two), and then some before a big pool party on the 12th.

I'll keep a better eye on it now so I don't come back with algae problems in the future!

[mitchryan912]

I went back and tracked the weather in the timeframe my FC levels were quite stable, and I think I can conclude 2 things:

1. FC stayed stable because there were a TON of cloudy & partly cloudy days here in the beginning of the month.
2. The chlorine I've been using since the 1st has been some bargain deal chlorine from Menards that was on sale for $1.99/gallon.

I'm guessing that the former helped considerably, but the latter... I think the 12.5% chlorine I've been using lately isn't actually the 12.5% that it's advertised as. I put in 1 gallon earlier today, and it only raised FC up from 2.0 to 4.5 ppm. I added another 2 qts about an hour ago, and will be testing it before I go to bed and then again in the AM, to see if there is anything funny going on.

EDIT: Just checked FC at night before bed, and it's up to 8.0 ppm, which is in line with what you'd expect with 10% chlorine (2.0 to 8.0 via 6 quarts.)

[Watermom]

You will definitely use less chlorine on cloudy days. And, I agree with you that 1.5 gallons (6 quarts) would raise your chlorine by about 6ppm if it were 10% sodium hypo. It is pretty typical for many of the bottles of liquid chlorine to not be the strength they are advertised. That will be especially true if they sit on a shelf for awhile in a hot store. That is one reason we like Walmart's generic bleach. They have a fast turnover and the bottles are in an air conditioned store which further slows the break down.

[mitchryan912]

My morning chlorine level was at 7.5ppm, so that seems like a reasonable amount of chlorine loss, especially if there might have been anything trying to bloom when the chlorine dropped low. We're expected to hit 90 degrees for the first time this year, so I'll be watching it like a hawk and probably doing a second test this evening to see how it's changed over the day.

I think I'll be going back to the pool store for 12.5% after I use up the remaining 3 gallon jugs I bought at Menards. I'm not even sure that the jugs I used previously were 10%, considering how ineffective at least one of them was. Roughly 2.5 gallons out of Midwest's 5 gallon jugs brought me from .5ppm to 5ppm 2 days later (and both measurements were done at Midwest, so who knows how accurate those were.)

This brings up a question I've been wondering about the "Best Guess" method: assuming a pool with 40 CYA, is <4 ppm FC pretty much equal to a pool with 0ppm CYA and 0 FC? If this isn't clear, does the CYA effectively bind up a lot of the chlorine such that it's there, but not always available until the CYA-chlorine bond separates? I guess I'm just curious why there is a minimum of 3ppm when CYA is between 30-50ppm?