Unexplained FC Consumption - SOLVED - although the Mystery Remains

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T

toofast

0
May 9, 2013
993
North East Ohio
Unexplained FC Consumption - it's back again!

So for those that have great memories...I am struggling to keep by pool clear this year.

I totally understand the TFP methods and they rock...problem is my FC is all over the board.

I am at my last straw...meaning I am totally confused...thought I had an Ammonia problem, then I passed OCLT, see below.

Just finished a SLAM with and passed the OCLT with flying numbers...went from 7.5 FC with 0 CC to 7.0 FC and 0 CC overnight...YEAH.

Decided to keep FC just a bit higher to make sure, so dosed accordingly to add 5 PPM of FC.

30 minutes after dose I test FC and my FC is 7.5 ???

So unless I lost 5 PPM from 7 AM - 12 PM with a CYA of 40 in a covered (solar) pool - I am clueless.

What other info do you need to try and help. Could Ammonia problem be so wacky and still be my problem ?

OR could my DPD or R-0871 be screwed up and giving me false results...and thus causing my FC to be way off (However I use a stenner, so my doses are very consistent)
 
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Re: Could bad DPD or R-0871 cause wacky results

If you had ammonia, you should be seeing CC numbers.
The pump was running after you added chlorine right?

Try adding some chlorine and testing the FC and CC after 30 minutes and lets make sure you see a rise and not that it was lost in the 5 hours (which could be possible).

It would be very rare for the powder to have a problem. How do you store your test kit?
 
Re: Could bad DPD or R-0871 cause wacky results

As for Ammonia - yeah that is kind of what I thought...during this WHOLE MESS I never had CC above .5

Yes, pump was running on low when injecting, then on high for 30 min after to get accurate mix. Was also running overnight on low when passed test overnight.

Test kit is stored inside in covered uv resistant box in dark under a cupboard. in winter stored in dark cool basement. Both DPD and 871 are on second season.

I will do the test and see what we come up with...still BAFFELED how I lost 5 PPM in 5 hours -but that is a different story I guess. Stay tuned...the test will have to be later this evening though.
 
Re: Could bad DPD or R-0871 cause wacky results

Well, the CYA protects a % of the FC ... so the higher the FC level, the more ppm you will lose. Although 5ppm in a covered pool with 40ppm CYA and in the morning hours seems a bit high.

Does not sound like you actually tested the FC around 12.5ppm though ... so maybe it did not actually rise that much.
 
Re: Could bad DPD or R-0871 cause wacky results

Slightly confused on your second point...meaning no I did not get a FC test at 12.5.

But if my FC test of 7.5 is accurate, what it meant was that the 5 PPM of FC I injected with my stenner were "eaten" by something or my FC Dropped from 7 to 2 between 7 AM and Noon.
 
Re: Could bad DPD or R-0871 cause wacky results

My point is ... maybe you did not actually inject 5ppm worth of chlorine ... maybe it is weaker or maybe it is not injecting as much as you think.
I though you tested 7.5 and then added 5ppm worth (not use the stenner), but did not test a 12.5ppm 30 minutes after adding it to confirm you had actually reach that level.
 
Re: Could bad DPD or R-0871 cause wacky results

Gotcha...totally understand.

My stenner is/was dead accurate - meaning I always do a calibration run, i.e. inject into a measuring cup against time to validate....and the bleach (brand new) is disappearing from the Stenner Jug.

I will try manually dosing (when not traveling) and try to pin point this madness.
 
Re: Could bad DPD or R-0871 cause wacky results

The amazing Chlorine consumption continues....

9 PM EST - 1.0 FC - a drop from 7.5 a bit after noon. CC is reading 0.0

Added 2 gallons manually of 5.25% to bring up to about 8 PPM of FC - will retest in a bit and post results.

I have a new disease - stand by :(
 
Re: Could bad DPD or R-0871 cause wacky results

Well....guess what...40 minutes later

FC - 8.0
CC - 0.0

I am totally clueless what is eating my FC - it must be some invisible strain of algae :confused:

Honestly, what else could it be...

I will do another OCLT and report what I find in the AM. Anything else you think I should do, just yell.
 

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Re: Could bad DPD or R-0871 cause wacky results

jblizzle said:
Well the kids could certainly account for some of that loss.
Click to expand...

Fair enough...so we (at least myself) is back to being 100% stumped...

Or can I somehow have some kind of invisible algae consuming chlorine and I need to SLAM over many many days to kill this unknown animal...if you remember, I travel a TON, so being able to SLAM over 4-5 days is impossible. (unless I take a vacation)

Best I can do is SLAM for a few days....pass OCLT then get on a plane.

Based on everything I know...it seems I have a bizarre strain of invisible algae, sucking most of my FC (never creating any CC) and because I can't SLAM for a week on end, somehow it is surviving and when my FC drops to NORMAL levels...it is strong enough to EAT that FC ?????

Added this thought....perhaps I am a candidate for polyquat to help me with this ?

Any other ideas ?
 
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Re: Could bad DPD or R-0871 cause wacky results

Sminor said:
Are you sure your CYA readings are accurate? From checking your posts it seems like you are only losing chlorine during the day...
Click to expand...

Great question....so I've tested (last was 3 days ago) CYA 4-5 times. Each time the results were as expected....i.e. started with 0 in spring - added enough to 20, week later CYA 20.

Last 2 tests were to validate target of 40 (after adding stabilizer) and both times I was clearly at LEAST 40, maybe a bit more.

I will certainly TEST AGAIN - but I have testing for CYA for some time and I do feel my numbers are accurate....but all things are possible. I will retest again to validate.
 
Re: Could bad DPD or R-0871 cause wacky results

Ok 12:30 PM results, last test at 6 AM showed FC at 6 PPM

NOW it is FC 8.5 / CC 0

I injected enough chlorine to get to FC 11 - so that means in 6 hours (3 without sun) I lost 2.5 PPM - WAY TOO MUCH.

Water still clear.

Next steps...retest CYA when I land and then retest stenner to see if dosing is wacked out (but not sure how the pump all of a sudden starts dosing at 50% the rate it normally does.

Any other ideas....or questions, just yell!
 
Re: Could bad DPD or R-0871 cause wacky results

I've never used a Stenner but I assume it's a peristaltic pump - and any degradation of the pump tube can cause dosing problems. If you have a spare, just change the tube before making any pump adjustments.

Just my .02
 

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