Differences in chem test results

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JoyfulNoise said:
TFP recommends 70-90ppm. I keep mine at 70ppm. 90ppm means a higher FC which means, ultimately, running your SWCG harder. Anything over 100ppm is asking for trouble. I worked on a pool with a 150ppm CYA level and the SWCG just could not produce enough FC to stay within the TFP Recommended levels. The pool eventually went cloudy when the warm weather hit and I had to do a partial drain to get the CYA down.
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This is not exactly true. The higher CYA level should in fact let the SWG work less hard because less FC would be lost to the sun. The danger of the higher CYA level would be if you developed a problem and had to SLAM the pool.

For the pool with 150ppm CYA, likely there was stuff growing the in the pool when the FC was not started high enough ... and thus the SWG could not compete with the growing organics. IF the pool started out "sterile" the SWG should have been able to keep up.
 
jblizzle said:
This is not exactly true. The higher CYA level should in fact let the SWG work less hard because less FC would be lost to the sun. The danger of the higher CYA level would be if you developed a problem and had to SLAM the pool.

For the pool with 150ppm CYA, likely there was stuff growing the in the pool when the FC was not started high enough ... and thus the SWG could not compete with the growing organics. IF the pool started out "sterile" the SWG should have been able to keep up.
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This is why I'm not too worried, I think.

Since I started with fresh municipal water and I'll be keeping the FAC level in check, there should be no problems that would lead to the need to SLAM, correct? If that's the case, I'll just let the CYA drift down over time through backwashing.
 
jblizzle said:
This is not exactly true. The higher CYA level should in fact let the SWG work less hard because less FC would be lost to the sun. The danger of the higher CYA level would be if you developed a problem and had to SLAM the pool.

For the pool with 150ppm CYA, likely there was stuff growing the in the pool when the FC was not started high enough ... and thus the SWG could not compete with the growing organics. IF the pool started out "sterile" the SWG should have been able to keep up.
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For the 150ppm CYA pool, it was a small community pool in a small HOA I rented in (only ~15 homes or so) The SWCG, as best as I could tell, was not properly sized for the pool volume or bather load (it should have been twice as big). Therefore, the cell had to struggle to keep up with the organic bather waste oxidation and the higher CYA. For whatever photo-protective effect it was having, the higher CYA was requiring the higher FC/CYA ratio. The cell just could not keep up with the compounding demands (higher FC needed for bather waste and higher FC needed to maintain proper disinfection ratio). Even after SLAM'ing the pool to kill everything off and oxidize any residual waste, the cell had to run hard. We decided to drain the pool by 50% and rebalance the water with a CYA of 80ppm. The pool had enough shade throughout the day that it did not need the higher CYA levels. That worked better but the cell had to work hard nonetheless.

My current pool get lots of the hot Tucson sun (full sun from 8:30AM to 4PM) and 70ppm CYA works great.
 
The required FC/CYA ratio is the same ... just that the FC level needed to be higher for the higher CYA level.

A SWG can only add a set # ppm of FC in a day ... In a clean pool, the SWG should have been able to keep up even with the elevated CYA because fewer ppm of FC would have been lost to the sun. Not sure why that was not the case in your experience. Although given the public nature of the pool, that adds a lot of variables.
 
jblizzle said:
Although given the public nature of the pool, that adds a lot of variables.
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With ~ 20 kids in the neighborhood at the time, variables = pee

:foot: Yes, you are right, ratio is constant. Meant to say proportionally higher FC to maintain the correct sanitary ratio.
 
Ok just did another round of tests and it looks good. I'm not sure if there's a bunch of CYA that hasn't dissolved yet though. Does is dissolve pretty quickly since I didn't use the sock method?

This is about 5 hours after adding 16lbs CYA and 3lbs dry cal-hypo. Pump has been running full speed.

CYA: 50ppm
PH: 7.2
FC: 10+ ppm due to cal-hypo (do not have the good powder test yet, it's in the mail)
TA: 180 ppm
CH: 160 ppm

TA needs to be lowered, but if I keep adding acid and running the waterfall to raise PH, it should go lower - correct?

I'm going to add calcium flakes shortly as well.
 

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You have a basic push-pull backwash valve that does not have the waste or recirculate function. But, you have the spigot above the pump that you could use to slowly remove some water.
 
Nevermind, I went outside like recommended and got around 50 again (it's storming, that rule slipped my mind :sleep:).

The CYA test seems kind of subjective (can I still kinda see the dot?!) and dependent on how much sunlight there is (I know back to the sun too).

Any tips on getting an accurate reading beyond that? I watched the videos, I guess you just get better at it over time.
 
Get the 50ppm standard CYA solution from TFTestKits.net and play around with it until you find the exact test conditions that makes the dot disappear at the 50ppm mark.


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Just did another round of tests today after adding 25lbs Calcium in the morning and getting my FC powder test.

PH: 7.6
FC: 5.5
CC: 0
TA: 140
CYA: 55
CH: 220

Everything pretty solid except for the TA and slightly low CH?
 
Does your full water have calcium in it? If so, you could probably just leave the CH alone a let it come up on its own. Did the builder require a specific number? You're at the low end of the TFPC Recommended level.

Your TA will come down naturally as you regularly add acid to keep the pH in check. If the full water has high TA, then you might need to be a bit more aggressive about reducing it.

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JoyfulNoise said:
Does your full water have calcium in it? If so, you could probably just leave the CH alone a let it come up on its own. Did the builder require a specific number? You're at the low end of the TFPC Recommended level.

Your TA will come down naturally as you regularly add acid to keep the pH in check. If the full water has high TA, then you might need to be a bit more aggressive about reducing it.

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I'm assuming you mean fill water? I haven't tested it yet, but we are on a well that has some pretty nasty water. Very hard/metallic. We didn't fill the pool with too much of that though, had municipal water trucked in.

I was either going to let the TA drift down itself, or lower it to 7.0 and run the waterfall all day, depending on what you guys recommended.

The guy the PB sent told us 200-400 for CH. He said to put the full 50lbs of calcium in .. but I learned the hard way with CYA and only did 25lbs.

Also, my CYA is going to go up from using tri-chlor this first month, but that's actually good since the recommended CYA levels are higher for salt - right?
 

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