Recent Drain/Refill and NO FC detected

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az_fam

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Nov 11, 2015
43
Gilbert, AZ
Hello all!

I just recently drained and refilled our pool due to a CYA level in the 150-200 range. After doing this, I have been checking chemicals daily. Yesterday my FC was at 0, as it is today! I am using the TFP calculator and it told me to add 110 oz bleach, which I do, but then by the next morning there's NO detectible chlorine. Same thing happened this am. Instead of adding bleach, I threw in there trichlor tabs bc I KNOW that'll work. (As a side note, by CYA is now 0, so adding a few pucks will only help me). Could the 0 CYA have anything to do with the missing FC after adding a whole jug of bleach? Am I doing something wrong? Missing something?? Yesterday's numbers FC .5, CC .5, pH 7.7, TA 110, CYA 0.

Thanks!
 
Chlorine breaks down quite quickly in sunlight if you have no CYA in the water (I was recently reading up on this for my own reasons, and came across a pretty authoritative post saying the half life of chlorine, in full sun, with no CYA, is on the order of 35 minutes). Since you probably have plenty of sunlight in AZ, this is the likely reason for your disappearing chlorine. Put in some stabilizer (carefully, of course, so you don't get back to the previous untenable levels)!
 
Are you adding 8% or 12% Chlorine? That's odd that you would lose 6ppm. Even when I had my pool filled I was only losing 3ppm per 24 hours with no CYA in the water.


Get the CYA in to appropriate levels, you will need to check FC levels twice per day and add as needed.
 
There could also be something organic in the water consuming the FC. Although with no CYA, 6ppm FC would be like a nuclear holocaust.

When my CYA unexpectedly dropped to under 20, I was losing 5-6 PPM FC during the day. Granted that was in the brutal sun of June or July.

I would go to Walmart and get a jug of the HTH Stabilizer and get up to at least 30 ppm CYA and adjust as needed from there.
 
I'm right down the street from you - I lose 1.5 to 2 ppm per day on average with a CYA of 50. With 0 CYA, you'll burn through that 6 ppm in a day easily. As suggested, add some stabilizer. That 4 pound bottle of granular will add 32 ppm CYA to your 15k pool.

Divide it up into 2 socks - put one in the skimmer and hang the other in front of a return jets. All 4# at once in the skimmer may reduce water flow too much. Squeeze the socks several times a day to help dissolve/dissipate the CYA. You can bump it up the rest of the way to the 40-50 range with pucks - just use PoolMath to figure out how many. Save the rest of the pucks for when you go on vacation.
 
You guys, as usual, are the BEST! Thanks for all of the tips. I will get the stabilizer in the socks asap and see if getting my CYA to 30 will help keep the chlorine in the pool. I am using the bleach from was mart right now and its 8%.Going to the calculator right now to see how much CYA to add. Guess I shouldn't have drained the WHOLE pool :). I will also do that overnight test because we did have algae before the drain (a mild case, but algae nonetheless).

I'll keep you all posted!
 
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